| Seq | Timestamp | Type | Name | Duration |
|---|---|---|---|---|
| 0/0 | 2026/09/22 05:23 | flow | patch-triage |
4mArgs:null Results: {
"EnableConfigs": [
"NET_CLS_ACT",
"NET_ACT_CONNMARK",
"NET_ACT_MIRRED",
"NET_ACT_MPLS",
"NET_ACT_NAT",
"NET_ACT_SIMP",
"NET_ACT_SKBMOD",
"NF_CONNTRACK",
"NF_CONNTRACK_MARK"
],
"FocusSymbols": [
"tcf_add_notify_msg",
"tcf_del_notify_msg",
"tcf_connmark_get_fill_size",
"tcf_mirred_get_fill_size",
"tcf_mpls_get_fill_size",
"tcf_nat_get_fill_size",
"tcf_simp_get_fill_size",
"tcf_skbmod_get_fill_size"
],
"KMSANReasoning": "The patch series improves the buffer allocation size calculations for netlink notification skbs in the TC action subsystem (net/sched). Specifically, it accounts for potential warning messages from netlink_ext_ack in tcf_action_warn_attr_size() when allocating skbs in tcf_del_notify_msg() and tcf_add_notify_msg(), and implements/corrects the .get_fill_size callback for several action modules (act_connmark, act_mirred, act_mpls, act_nat, act_simple, act_skbmod) so that the maximum size needed by their dump callbacks is pre-calculated accurately.\n\nThese changes only affect the size argument passed to alloc_skb() to prevent buffer exhaustion and message trimming during tca_get_fill(). They do not introduce, modify, or expose any uninitialized memory or info-leaks:\n1. No changes are made to how data is serialized or dumped into netlink skbs; the dump functions themselves are unchanged and already properly initialize all structs before calling nla_put().\n2. The skb buffer sizing does not affect the amount of data copied to userspace, as skb-\u003elen is determined strictly by the formatted netlink attributes.\n3. No uninitialized variables, heap allocations, or struct fields are read or branched upon.\n\nBecause there are no uninitialized memory risks or kernel-to-user info-leak risks, running a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false,
"Reasoning": "The patch modifies buffer size calculations for netlink TC action notification messages (accounting for extack warning messages) in net/sched/act_api.c and adds/updates .get_fill_size callbacks across multiple traffic control actions (connmark, mirred, mpls, nat, simple, skbmod). These changes affect skb allocation sizing during netlink action operations (RTM_NEWACTION, RTM_DELACTION), which are reachable from userspace via rtnetlink and warrant fuzzing to catch potential buffer miscalculations, memory corruption, or message formatting errors.",
"WorthFuzzing": true
} |
| 1/1 | 2026/09/22 05:23 | action | read-patch-diff |
0mArgs:null Results: {
"PatchDiff": "commit 5d4c87dd0e20cf5216e924576264f1cef012ba5e\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Tue Sep 22 05:23:24 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/net/sched/act_api.c b/net/sched/act_api.c\nindex 3f653721c45fe..db06ddcf6ae67 100644\n--- a/net/sched/act_api.c\n+++ b/net/sched/act_api.c\n@@ -475,6 +475,15 @@ static size_t tcf_action_full_attrs_size(size_t sz)\n \t\t+ sz;\n }\n \n+/* tca_get_fill() may append TCA_ROOT_EXT_WARN_MSG from extack-\u003e_msg */\n+static size_t tcf_action_warn_attr_size(const struct netlink_ext_ack *extack)\n+{\n+\tif (unlikely(extack \u0026\u0026 extack-\u003e_msg))\n+\t\treturn nla_total_size(strlen(extack-\u003e_msg) + 1);\n+\n+\treturn 0;\n+}\n+\n static size_t tcf_action_fill_size(const struct tc_action *act)\n {\n \tsize_t sz = tcf_action_shared_attrs_size(act);\n@@ -1980,7 +1989,8 @@ static struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,\n {\n \tstruct sk_buff *skb;\n \n-\tskb = alloc_skb(max(attr_size, NLMSG_GOODSIZE), GFP_KERNEL);\n+\tskb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),\n+\t\t\t NLMSG_GOODSIZE), GFP_KERNEL);\n \tif (!skb)\n \t\treturn ERR_PTR(-ENOBUFS);\n \n@@ -2078,7 +2088,8 @@ static struct sk_buff *tcf_add_notify_msg(struct net *net, struct nlmsghdr *n,\n {\n \tstruct sk_buff *skb;\n \n-\tskb = alloc_skb(max(attr_size, NLMSG_GOODSIZE), GFP_KERNEL);\n+\tskb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),\n+\t\t\t NLMSG_GOODSIZE), GFP_KERNEL);\n \tif (!skb)\n \t\treturn ERR_PTR(-ENOBUFS);\n \ndiff --git a/net/sched/act_connmark.c b/net/sched/act_connmark.c\nindex c634af5edfcdc..0b6ac6be60d24 100644\n--- a/net/sched/act_connmark.c\n+++ b/net/sched/act_connmark.c\n@@ -236,12 +236,18 @@ static void tcf_connmark_cleanup(struct tc_action *a)\n \t\tkfree_rcu(parms, rcu);\n }\n \n+static size_t tcf_connmark_get_fill_size(const struct tc_action *act)\n+{\n+\treturn nla_total_size(sizeof(struct tc_connmark)); /* TCA_CONNMARK_PARMS */\n+}\n+\n static struct tc_action_ops act_connmark_ops = {\n \t.kind\t\t=\t\"connmark\",\n \t.id\t\t=\tTCA_ID_CONNMARK,\n \t.owner\t\t=\tTHIS_MODULE,\n \t.act\t\t=\ttcf_connmark_act,\n \t.dump\t\t=\ttcf_connmark_dump,\n+\t.get_fill_size\t=\ttcf_connmark_get_fill_size,\n \t.init\t\t=\ttcf_connmark_init,\n \t.cleanup\t=\ttcf_connmark_cleanup,\n \t.size\t\t=\tsizeof(struct tcf_connmark_info),\ndiff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c\nindex 553342c55cf7c..1c98e4d81ebe6 100644\n--- a/net/sched/act_mirred.c\n+++ b/net/sched/act_mirred.c\n@@ -607,7 +607,8 @@ tcf_mirred_get_dev(const struct tc_action *a,\n \n static size_t tcf_mirred_get_fill_size(const struct tc_action *act)\n {\n-\treturn nla_total_size(sizeof(struct tc_mirred));\n+\treturn nla_total_size(sizeof(struct tc_mirred)) /* TCA_MIRRED_PARMS */\n+\t\t+ nla_total_size(sizeof(u32)); /* TCA_MIRRED_BLOCKID */\n }\n \n static void tcf_offload_mirred_get_dev(struct flow_action_entry *entry,\ndiff --git a/net/sched/act_mpls.c b/net/sched/act_mpls.c\nindex 4ea8b2e08c3a4..aa56521b71798 100644\n--- a/net/sched/act_mpls.c\n+++ b/net/sched/act_mpls.c\n@@ -438,12 +438,23 @@ static int tcf_mpls_offload_act_setup(struct tc_action *act, void *entry_data,\n \treturn 0;\n }\n \n+static size_t tcf_mpls_get_fill_size(const struct tc_action *act)\n+{\n+\treturn nla_total_size(sizeof(struct tc_mpls)) /* TCA_MPLS_PARMS */\n+\t\t+ nla_total_size(sizeof(u32)) /* TCA_MPLS_LABEL */\n+\t\t+ nla_total_size(sizeof(u8)) /* TCA_MPLS_TC */\n+\t\t+ nla_total_size(sizeof(u8)) /* TCA_MPLS_TTL */\n+\t\t+ nla_total_size(sizeof(u8)) /* TCA_MPLS_BOS */\n+\t\t+ nla_total_size(sizeof(u16)); /* TCA_MPLS_PROTO */\n+}\n+\n static struct tc_action_ops act_mpls_ops = {\n \t.kind\t\t=\t\"mpls\",\n \t.id\t\t=\tTCA_ID_MPLS,\n \t.owner\t\t=\tTHIS_MODULE,\n \t.act\t\t=\ttcf_mpls_act,\n \t.dump\t\t=\ttcf_mpls_dump,\n+\t.get_fill_size\t=\ttcf_mpls_get_fill_size,\n \t.init\t\t=\ttcf_mpls_init,\n \t.cleanup\t=\ttcf_mpls_cleanup,\n \t.offload_act_setup =\ttcf_mpls_offload_act_setup,\ndiff --git a/net/sched/act_nat.c b/net/sched/act_nat.c\nindex abb332dee836d..a201979ac7cf7 100644\n--- a/net/sched/act_nat.c\n+++ b/net/sched/act_nat.c\n@@ -313,12 +313,18 @@ static void tcf_nat_cleanup(struct tc_action *a)\n \t\tkfree_rcu(parms, rcu);\n }\n \n+static size_t tcf_nat_get_fill_size(const struct tc_action *act)\n+{\n+\treturn nla_total_size(sizeof(struct tc_nat)); /* TCA_NAT_PARMS */\n+}\n+\n static struct tc_action_ops act_nat_ops = {\n \t.kind\t\t=\t\"nat\",\n \t.id\t\t=\tTCA_ID_NAT,\n \t.owner\t\t=\tTHIS_MODULE,\n \t.act\t\t=\ttcf_nat_act,\n \t.dump\t\t=\ttcf_nat_dump,\n+\t.get_fill_size\t=\ttcf_nat_get_fill_size,\n \t.init\t\t=\ttcf_nat_init,\n \t.cleanup\t=\ttcf_nat_cleanup,\n \t.size\t\t=\tsizeof(struct tcf_nat),\ndiff --git a/net/sched/act_simple.c b/net/sched/act_simple.c\nindex 8e69a919b4fee..80e5084b4dbd7 100644\n--- a/net/sched/act_simple.c\n+++ b/net/sched/act_simple.c\n@@ -79,6 +79,12 @@ static int reset_policy(struct tc_action *a, const struct nlattr *defdata,\n \treturn 0;\n }\n \n+static size_t tcf_simp_get_fill_size(const struct tc_action *act)\n+{\n+\treturn nla_total_size(sizeof(struct tc_defact)) /* TCA_DEF_PARMS */\n+\t\t+ nla_total_size(SIMP_MAX_DATA); /* TCA_DEF_DATA */\n+}\n+\n static const struct nla_policy simple_policy[TCA_DEF_MAX + 1] = {\n \t[TCA_DEF_PARMS]\t= { .len = sizeof(struct tc_defact) },\n \t[TCA_DEF_DATA]\t= { .type = NLA_STRING, .len = SIMP_MAX_DATA },\n@@ -204,6 +210,7 @@ static struct tc_action_ops act_simp_ops = {\n \t.owner\t\t=\tTHIS_MODULE,\n \t.act\t\t=\ttcf_simp_act,\n \t.dump\t\t=\ttcf_simp_dump,\n+\t.get_fill_size\t=\ttcf_simp_get_fill_size,\n \t.cleanup\t=\ttcf_simp_release,\n \t.init\t\t=\ttcf_simp_init,\n \t.size\t\t=\tsizeof(struct tcf_defact),\ndiff --git a/net/sched/act_skbmod.c b/net/sched/act_skbmod.c\nindex 7579cf1e0ff37..09e9dcf582531 100644\n--- a/net/sched/act_skbmod.c\n+++ b/net/sched/act_skbmod.c\n@@ -279,12 +279,21 @@ static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,\n \treturn -1;\n }\n \n+static size_t tcf_skbmod_get_fill_size(const struct tc_action *act)\n+{\n+\treturn nla_total_size(sizeof(struct tc_skbmod)) /* TCA_SKBMOD_PARMS */\n+\t\t+ nla_total_size(ETH_ALEN) /* TCA_SKBMOD_DMAC */\n+\t\t+ nla_total_size(ETH_ALEN) /* TCA_SKBMOD_SMAC */\n+\t\t+ nla_total_size(sizeof(u16)); /* TCA_SKBMOD_ETYPE */\n+}\n+\n static struct tc_action_ops act_skbmod_ops = {\n \t.kind\t\t=\t\"skbmod\",\n \t.id\t\t=\tTCA_ACT_SKBMOD,\n \t.owner\t\t=\tTHIS_MODULE,\n \t.act\t\t=\ttcf_skbmod_act,\n \t.dump\t\t=\ttcf_skbmod_dump,\n+\t.get_fill_size\t=\ttcf_skbmod_get_fill_size,\n \t.init\t\t=\ttcf_skbmod_init,\n \t.cleanup\t=\ttcf_skbmod_cleanup,\n \t.size\t\t=\tsizeof(struct tcf_skbmod),\n"
} |
| 2/1 | 2026/09/22 05:23 | agent | patch-evaluator |
2mModel:core Args: null Results: {
"EnableConfigs": [
"NET_CLS_ACT",
"NET_ACT_CONNMARK",
"NET_ACT_MIRRED",
"NET_ACT_MPLS",
"NET_ACT_NAT",
"NET_ACT_SIMP",
"NET_ACT_SKBMOD",
"NF_CONNTRACK",
"NF_CONNTRACK_MARK"
],
"FocusSymbols": [
"tcf_add_notify_msg",
"tcf_del_notify_msg",
"tcf_connmark_get_fill_size",
"tcf_mirred_get_fill_size",
"tcf_mpls_get_fill_size",
"tcf_nat_get_fill_size",
"tcf_simp_get_fill_size",
"tcf_skbmod_get_fill_size"
],
"Reasoning": "The patch modifies buffer size calculations for netlink TC action notification messages (accounting for extack warning messages) in net/sched/act_api.c and adds/updates .get_fill_size callbacks across multiple traffic control actions (connmark, mirred, mpls, nat, simple, skbmod). These changes affect skb allocation sizing during netlink action operations (RTM_NEWACTION, RTM_DELACTION), which are reachable from userspace via rtnetlink and warrant fuzzing to catch potential buffer miscalculations, memory corruption, or message formatting errors.",
"WorthFuzzing": true
}Instruction: You are an expert Linux kernel maintainer and security engineer.
Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller.
IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on internal assumptions. You must actively use your code access
tools to inspect the actual source code, callers, and surrounding context.
================================================================================
1. CORE TRIAGE PHILOSOPHY
================================================================================
The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs,
and newly triggered assertions introduced by the patch series.
- REACHABILITY IS THE PRIMARY GATE:
Fuzzing can only discover bugs in code that can actually execute in standard virtualized
environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap).
If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed,
regardless of whether it adds assertions or complex logic.
- DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS:
Patch authors routinely label changes as "cleanups", "refactorings", or state
"No functional change intended". Do NOT take these claims at face value.
Code refactorings that rearrange logic, introduce helper functions, or alter state management
in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs.
If reachable executable code is modified or refactored, it MUST be fuzzed.
- NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED:
When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON*, VM_WARN_ON*,
BUG_ON*, lockdep_assert*) in reachable code paths, it enforces new or stricter invariants.
Even if the author believes the invariant always holds, fuzzing is essential to verify whether
an unusual sequence of operations can violate it.
================================================================================
2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA)
================================================================================
Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories:
- Non-kernel and non-executable changes:
* Modifications to Documentation/, comments, or spelling fixes.
* User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/)
that do not affect the compiled kernel image (vmlinux) or kernel modules.
* Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints
that do not alter control flow or data structures.
* Build system or Kconfig changes that do not alter compiled C logic.
- Structurally unreachable hardware:
* Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed,
ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU.
- Unreachable execution paths:
* Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during
physical PCI hot-unplug or manual sysfs driver unbinding.
* Code paths exclusive to architectures other than the target architecture.
================================================================================
3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA)
================================================================================
Return WorthFuzzing=true whenever the patch touches reachable executable code, including:
- Core Subsystems:
* Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/),
BPF, scheduler, core networking, VFS, or syscall handling.
- Refactorings and Code Cleanups:
* Any restructuring of reachable data structures, helper abstractions, or algorithm flows.
- Runtime Assertions and Defensive Checks:
* Any introduction or alteration of assertions (WARN_ON*, VM_WARN_ON*, BUG_ON*, etc.) in reachable paths.
- Reachable Drivers and Protocols:
* Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.).
================================================================================
4. EXTRACTING FocusSymbols (PREVENTING DILUTION)
================================================================================
When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer:
- AVOID UBIQUITOUS LIFECYCLE HOT-PATHS:
Do NOT list generic, ubiquitous functions called by almost every program in the corpus
(including, but not limited to: general memory allocators and deallocators, page fault
and trap handlers, or core synchronization primitives; this is not an exhaustive list).
Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused",
which severely dilutes fuzzing effort away from the actual changes.
- TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS:
List functions that specifically implement the logic being added or altered, or direct API entrypoints
for the subsystem feature under review.
- HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h):
Compiler-inlined static functions (such as static inlines in mm/*.h or include/linux/*.h) lack
distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters.
If the changes are primarily in static inline helpers, identify non-static, feature-specific caller
functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers).
================================================================================
5. IDENTIFYING EnableConfigs
================================================================================
Identify any specific CONFIG_ options required to properly compile and reach the modified code:
- Inspect Kconfig files and #ifdef guards; do not make assumptions.
- Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed.
- Strip any 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
Prefer calling several tools at the same time to save round-trips.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt: Target architecture: amd64
For your convenience, here is the diff of the changes:
commit 5d4c87dd0e20cf5216e924576264f1cef012ba5e
Author: syz-cluster <triage@syzkaller.com>
Date: Tue Sep 22 05:23:24 2026 +0000
syz-cluster: applied patch under review
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 3f653721c45fe..db06ddcf6ae67 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -475,6 +475,15 @@ static size_t tcf_action_full_attrs_size(size_t sz)
+ sz;
}
+/* tca_get_fill() may append TCA_ROOT_EXT_WARN_MSG from extack->_msg */
+static size_t tcf_action_warn_attr_size(const struct netlink_ext_ack *extack)
+{
+ if (unlikely(extack && extack->_msg))
+ return nla_total_size(strlen(extack->_msg) + 1);
+
+ return 0;
+}
+
static size_t tcf_action_fill_size(const struct tc_action *act)
{
size_t sz = tcf_action_shared_attrs_size(act);
@@ -1980,7 +1989,8 @@ static struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,
{
struct sk_buff *skb;
- skb = alloc_skb(max(attr_size, NLMSG_GOODSIZE), GFP_KERNEL);
+ skb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),
+ NLMSG_GOODSIZE), GFP_KERNEL);
if (!skb)
return ERR_PTR(-ENOBUFS);
@@ -2078,7 +2088,8 @@ static struct sk_buff *tcf_add_notify_msg(struct net *net, struct nlmsghdr *n,
{
struct sk_buff *skb;
- skb = alloc_skb(max(attr_size, NLMSG_GOODSIZE), GFP_KERNEL);
+ skb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),
+ NLMSG_GOODSIZE), GFP_KERNEL);
if (!skb)
return ERR_PTR(-ENOBUFS);
diff --git a/net/sched/act_connmark.c b/net/sched/act_connmark.c
index c634af5edfcdc..0b6ac6be60d24 100644
--- a/net/sched/act_connmark.c
+++ b/net/sched/act_connmark.c
@@ -236,12 +236,18 @@ static void tcf_connmark_cleanup(struct tc_action *a)
kfree_rcu(parms, rcu);
}
+static size_t tcf_connmark_get_fill_size(const struct tc_action *act)
+{
+ return nla_total_size(sizeof(struct tc_connmark)); /* TCA_CONNMARK_PARMS */
+}
+
static struct tc_action_ops act_connmark_ops = {
.kind = "connmark",
.id = TCA_ID_CONNMARK,
.owner = THIS_MODULE,
.act = tcf_connmark_act,
.dump = tcf_connmark_dump,
+ .get_fill_size = tcf_connmark_get_fill_size,
.init = tcf_connmark_init,
.cleanup = tcf_connmark_cleanup,
.size = sizeof(struct tcf_connmark_info),
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 553342c55cf7c..1c98e4d81ebe6 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -607,7 +607,8 @@ tcf_mirred_get_dev(const struct tc_action *a,
static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
{
- return nla_total_size(sizeof(struct tc_mirred));
+ return nla_total_size(sizeof(struct tc_mirred)) /* TCA_MIRRED_PARMS */
+ + nla_total_size(sizeof(u32)); /* TCA_MIRRED_BLOCKID */
}
static void tcf_offload_mirred_get_dev(struct flow_action_entry *entry,
diff --git a/net/sched/act_mpls.c b/net/sched/act_mpls.c
index 4ea8b2e08c3a4..aa56521b71798 100644
--- a/net/sched/act_mpls.c
+++ b/net/sched/act_mpls.c
@@ -438,12 +438,23 @@ static int tcf_mpls_offload_act_setup(struct tc_action *act, void *entry_data,
return 0;
}
+static size_t tcf_mpls_get_fill_size(const struct tc_action *act)
+{
+ return nla_total_size(sizeof(struct tc_mpls)) /* TCA_MPLS_PARMS */
+ + nla_total_size(sizeof(u32)) /* TCA_MPLS_LABEL */
+ + nla_total_size(sizeof(u8)) /* TCA_MPLS_TC */
+ + nla_total_size(sizeof(u8)) /* TCA_MPLS_TTL */
+ + nla_total_size(sizeof(u8)) /* TCA_MPLS_BOS */
+ + nla_total_size(sizeof(u16)); /* TCA_MPLS_PROTO */
+}
+
static struct tc_action_ops act_mpls_ops = {
.kind = "mpls",
.id = TCA_ID_MPLS,
.owner = THIS_MODULE,
.act = tcf_mpls_act,
.dump = tcf_mpls_dump,
+ .get_fill_size = tcf_mpls_get_fill_size,
.init = tcf_mpls_init,
.cleanup = tcf_mpls_cleanup,
.offload_act_setup = tcf_mpls_offload_act_setup,
diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index abb332dee836d..a201979ac7cf7 100644
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -313,12 +313,18 @@ static void tcf_nat_cleanup(struct tc_action *a)
kfree_rcu(parms, rcu);
}
+static size_t tcf_nat_get_fill_size(const struct tc_action *act)
+{
+ return nla_total_size(sizeof(struct tc_nat)); /* TCA_NAT_PARMS */
+}
+
static struct tc_action_ops act_nat_ops = {
.kind = "nat",
.id = TCA_ID_NAT,
.owner = THIS_MODULE,
.act = tcf_nat_act,
.dump = tcf_nat_dump,
+ .get_fill_size = tcf_nat_get_fill_size,
.init = tcf_nat_init,
.cleanup = tcf_nat_cleanup,
.size = sizeof(struct tcf_nat),
diff --git a/net/sched/act_simple.c b/net/sched/act_simple.c
index 8e69a919b4fee..80e5084b4dbd7 100644
--- a/net/sched/act_simple.c
+++ b/net/sched/act_simple.c
@@ -79,6 +79,12 @@ static int reset_policy(struct tc_action *a, const struct nlattr *defdata,
return 0;
}
+static size_t tcf_simp_get_fill_size(const struct tc_action *act)
+{
+ return nla_total_size(sizeof(struct tc_defact)) /* TCA_DEF_PARMS */
+ + nla_total_size(SIMP_MAX_DATA); /* TCA_DEF_DATA */
+}
+
static const struct nla_policy simple_policy[TCA_DEF_MAX + 1] = {
[TCA_DEF_PARMS] = { .len = sizeof(struct tc_defact) },
[TCA_DEF_DATA] = { .type = NLA_STRING, .len = SIMP_MAX_DATA },
@@ -204,6 +210,7 @@ static struct tc_action_ops act_simp_ops = {
.owner = THIS_MODULE,
.act = tcf_simp_act,
.dump = tcf_simp_dump,
+ .get_fill_size = tcf_simp_get_fill_size,
.cleanup = tcf_simp_release,
.init = tcf_simp_init,
.size = sizeof(struct tcf_defact),
diff --git a/net/sched/act_skbmod.c b/net/sched/act_skbmod.c
index 7579cf1e0ff37..09e9dcf582531 100644
--- a/net/sched/act_skbmod.c
+++ b/net/sched/act_skbmod.c
@@ -279,12 +279,21 @@ static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,
return -1;
}
+static size_t tcf_skbmod_get_fill_size(const struct tc_action *act)
+{
+ return nla_total_size(sizeof(struct tc_skbmod)) /* TCA_SKBMOD_PARMS */
+ + nla_total_size(ETH_ALEN) /* TCA_SKBMOD_DMAC */
+ + nla_total_size(ETH_ALEN) /* TCA_SKBMOD_SMAC */
+ + nla_total_size(sizeof(u16)); /* TCA_SKBMOD_ETYPE */
+}
+
static struct tc_action_ops act_skbmod_ops = {
.kind = "skbmod",
.id = TCA_ACT_SKBMOD,
.owner = THIS_MODULE,
.act = tcf_skbmod_act,
.dump = tcf_skbmod_dump,
+ .get_fill_size = tcf_skbmod_get_fill_size,
.init = tcf_skbmod_init,
.cleanup = tcf_skbmod_cleanup,
.size = sizeof(struct tcf_skbmod),
|
| 3/2 | 2026/09/22 05:23 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 5594 output: 34 thoughts: 291 Thoughts: **Evaluating a Linux Kernel Patch for Syzkaller Fuzzing** Okay, so I need to assess this Linux kernel patch for its fuzzing potential with syzkaller. The instructions are pretty straightforward: essentially, I'm doing a risk analysis and a fuzzing worthiness evaluation. It looks like it's a routine QA/defensive engineering task, nothing particularly risky. The process is safe; I'm just reviewing a patch and determining if it's worth the fuzzing effort. First, I need to figure out if it's worth fuzzing at all. That's the key question: WorthFuzzing = true or false. Then, if it *is* worth it, I'll need to identify the crucial bits – the FocusSymbols and EnableConfigs. Finally, I'll record the findings with `set-results`. Looking at the patch diff... Ah, it's all within `net/sched/`. That's the core networking subsystem, specifically traffic control (TC) actions. Now, that's interesting. TC is definitely something that gets a lot of use, and network code is always ripe for fuzzing. I can reach it via netlink (rtnetlink), which is excellent because that means I can interact with it in a virtualized environment – ideal for syzkaller. I should be able to trigger the changes with rtnetlink messages. This is promising. Now, I'll dig into the details. Time to pull up the full git commit or the diff itself using my tools and see what's really going on in those files. Let's see if this looks like a promising target. |
| 4/2 | 2026/09/22 05:23 | tool | grepper |
0mArgs:{
"Expression": "tcf_action_warn_attr_size",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=470=static size_t tcf_action_full_attrs_size(size_t sz)\n--\nnet/sched/act_api.c-478-/* tca_get_fill() may append TCA_ROOT_EXT_WARN_MSG from extack-\u003e_msg */\nnet/sched/act_api.c:479:static size_t tcf_action_warn_attr_size(const struct netlink_ext_ack *extack)\nnet/sched/act_api.c-480-{\n--\nnet/sched/act_api.c=1985=static struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-1991-\nnet/sched/act_api.c:1992:\tskb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),\nnet/sched/act_api.c-1993-\t\t\t NLMSG_GOODSIZE), GFP_KERNEL);\n--\nnet/sched/act_api.c=2084=static struct sk_buff *tcf_add_notify_msg(struct net *net, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-2090-\nnet/sched/act_api.c:2091:\tskb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),\nnet/sched/act_api.c-2092-\t\t\t NLMSG_GOODSIZE), GFP_KERNEL);\n"
} |
| 5/2 | 2026/09/22 05:23 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 6684 output: 37 thoughts: 48 Thoughts: Here's my analysis of the situation, presented from my perspective as an expert: **Investigating `act_api.c` & Notification Message Handling** Okay, so I need to dig into `act_api.c`, specifically focusing on how `tcf_add_notify_msg` and `tcf_del_notify_msg` function within the larger context. My immediate focus is going to be tracing the interactions between those two functions and the `get_fill_size` call. I need to understand the relationship between adding, deleting, and calculating the size of these notification messages. This is likely a critical area for memory management or performance in this module. I'll be keeping an eye out for potential issues like memory leaks or inefficient buffer allocation if the size calculations are off or if the messages aren't properly released. Understanding the interplay between those three functions will give me the best view into the architecture. I'll be looking for any potential race conditions or synchronization issues around the addition/deletion of messages, particularly if multiple threads are involved. Let's see what the code reveals. |
| 6/2 | 2026/09/22 05:23 | tool | read-file |
0mArgs:{
"File": "net/sched/act_api.c",
"FirstLine": 470,
"LineCount": 40
}Results: {
"Contents": " 470:\tstatic size_t tcf_action_full_attrs_size(size_t sz)\n 471:\t{\n 472:\t\treturn NLMSG_HDRLEN /* struct nlmsghdr */\n 473:\t\t\t+ sizeof(struct tcamsg)\n 474:\t\t\t+ nla_total_size(0) /* TCA_ACT_TAB nested */\n 475:\t\t\t+ sz;\n 476:\t}\n 477:\t\n 478:\t/* tca_get_fill() may append TCA_ROOT_EXT_WARN_MSG from extack-\u003e_msg */\n 479:\tstatic size_t tcf_action_warn_attr_size(const struct netlink_ext_ack *extack)\n 480:\t{\n 481:\t\tif (unlikely(extack \u0026\u0026 extack-\u003e_msg))\n 482:\t\t\treturn nla_total_size(strlen(extack-\u003e_msg) + 1);\n 483:\t\n 484:\t\treturn 0;\n 485:\t}\n 486:\t\n 487:\tstatic size_t tcf_action_fill_size(const struct tc_action *act)\n 488:\t{\n 489:\t\tsize_t sz = tcf_action_shared_attrs_size(act);\n 490:\t\n 491:\t\tif (act-\u003eops-\u003eget_fill_size)\n 492:\t\t\treturn act-\u003eops-\u003eget_fill_size(act) + sz;\n 493:\t\treturn sz;\n 494:\t}\n 495:\t\n 496:\tstatic int\n 497:\ttcf_action_dump_terse(struct sk_buff *skb, struct tc_action *a, bool from_act)\n 498:\t{\n 499:\t\tunsigned char *b = skb_tail_pointer(skb);\n 500:\t\tstruct tc_cookie *cookie;\n 501:\t\n 502:\t\tif (nla_put_string(skb, TCA_ACT_KIND, a-\u003eops-\u003ekind))\n 503:\t\t\tgoto nla_put_failure;\n 504:\t\tif (tcf_action_copy_stats(skb, a, 0))\n 505:\t\t\tgoto nla_put_failure;\n 506:\t\tif (from_act \u0026\u0026 nla_put_u32(skb, TCA_ACT_INDEX, a-\u003etcfa_index))\n 507:\t\t\tgoto nla_put_failure;\n 508:\t\n 509:\t\trcu_read_lock();\n"
} |
| 7/2 | 2026/09/22 05:23 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 7680 output: 38 thoughts: 29 Thoughts: Okay, let's dive into this code. **Investigating `tcf_del_notify_msg` and `tcf_add_notify_msg`** Alright, I need to get a clear understanding of how these functions, `tcf_del_notify_msg` and `tcf_add_notify_msg`, are being utilized. My first step is going to be tracing down all of the places where they're called. I want a complete picture of their immediate callers. Then, I need to understand how those callers are *using* these notification message functions. What's the broader context? What data are they manipulating, and what's the purpose of the notifications? This will illuminate the role these functions play within the larger system and highlight any potential areas of concern. It’s about understanding their precise behavior within the flow of execution. |
| 8/2 | 2026/09/22 05:23 | tool | read-file |
0mArgs:{
"File": "net/sched/act_api.c",
"FirstLine": 1975,
"LineCount": 50
}Results: {
"Contents": "1975:\t\t\t\t}\n1976:\t\t\t\tmutex_unlock(\u0026idrinfo-\u003elock);\n1977:\t\t\t}\n1978:\t\t}\n1979:\t\tmutex_unlock(\u0026act_id_mutex);\n1980:\t\tup_read(\u0026net_rwsem);\n1981:\t\n1982:\t\treturn 0;\n1983:\t}\n1984:\t\n1985:\tstatic struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,\n1986:\t\t\t\t\t\t struct tc_action *actions[],\n1987:\t\t\t\t\t\t u32 portid, size_t attr_size,\n1988:\t\t\t\t\t\t struct netlink_ext_ack *extack)\n1989:\t{\n1990:\t\tstruct sk_buff *skb;\n1991:\t\n1992:\t\tskb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),\n1993:\t\t\t\t NLMSG_GOODSIZE), GFP_KERNEL);\n1994:\t\tif (!skb)\n1995:\t\t\treturn ERR_PTR(-ENOBUFS);\n1996:\t\n1997:\t\tif (tca_get_fill(skb, actions, portid, n-\u003enlmsg_seq, 0, RTM_DELACTION,\n1998:\t\t\t\t 0, 2, extack) \u003c= 0) {\n1999:\t\t\tNL_SET_ERR_MSG(extack, \"Failed to fill netlink TC action attributes\");\n2000:\t\t\tkfree_skb(skb);\n2001:\t\t\treturn ERR_PTR(-EINVAL);\n2002:\t\t}\n2003:\t\n2004:\t\treturn skb;\n2005:\t}\n2006:\t\n2007:\tstatic int tcf_del_notify(struct net *net, struct nlmsghdr *n,\n2008:\t\t\t\t struct tc_action *actions[], u32 portid,\n2009:\t\t\t\t size_t attr_size, struct netlink_ext_ack *extack)\n2010:\t{\n2011:\t\tstruct sk_buff *skb;\n2012:\t\tint ret;\n2013:\t\n2014:\t\tif (!rtnl_notify_needed(net, n-\u003enlmsg_flags, RTNLGRP_TC)) {\n2015:\t\t\tskb = NULL;\n2016:\t\t} else {\n2017:\t\t\tskb = tcf_del_notify_msg(net, n, actions, portid, attr_size,\n2018:\t\t\t\t\t\t extack);\n2019:\t\t\tif (IS_ERR(skb))\n2020:\t\t\t\treturn PTR_ERR(skb);\n2021:\t\t}\n2022:\t\n2023:\t\t/* now do the delete */\n2024:\t\tret = tcf_action_delete(net, actions);\n"
} |
| 9/2 | 2026/09/22 05:23 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 8708 output: 38 thoughts: 17 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: **Investigating a Notification Mechanism** Okay, so we're looking at notification mechanisms and I need to make sure we've covered our bases. I think we need to double-check `tcf_add_notify_msg` as well. It's probably related, and since we're already digging into this area, it would be a missed opportunity to not also give that specific function a once-over as well. Might be something subtly wrong with the way it’s interacting with other parts of the system or even some of the same core issues we're trying to resolve in this entire subsystem. Better to get it all looked at during a sweep like this, to ensure the notification mechanisms as a whole work, since they are so tightly knit. |
| 10/2 | 2026/09/22 05:23 | tool | read-file |
0mArgs:{
"File": "net/sched/act_api.c",
"FirstLine": 2080,
"LineCount": 40
}Results: {
"Contents": "2080:\t\ttcf_action_put_many(actions);\n2081:\t\treturn ret;\n2082:\t}\n2083:\t\n2084:\tstatic struct sk_buff *tcf_add_notify_msg(struct net *net, struct nlmsghdr *n,\n2085:\t\t\t\t\t\t struct tc_action *actions[],\n2086:\t\t\t\t\t\t u32 portid, size_t attr_size,\n2087:\t\t\t\t\t\t struct netlink_ext_ack *extack)\n2088:\t{\n2089:\t\tstruct sk_buff *skb;\n2090:\t\n2091:\t\tskb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),\n2092:\t\t\t\t NLMSG_GOODSIZE), GFP_KERNEL);\n2093:\t\tif (!skb)\n2094:\t\t\treturn ERR_PTR(-ENOBUFS);\n2095:\t\n2096:\t\tif (tca_get_fill(skb, actions, portid, n-\u003enlmsg_seq, n-\u003enlmsg_flags,\n2097:\t\t\t\t RTM_NEWACTION, 0, 0, extack) \u003c= 0) {\n2098:\t\t\tNL_SET_ERR_MSG(extack, \"Failed to fill netlink attributes while adding TC action\");\n2099:\t\t\tkfree_skb(skb);\n2100:\t\t\treturn ERR_PTR(-EINVAL);\n2101:\t\t}\n2102:\t\n2103:\t\treturn skb;\n2104:\t}\n2105:\t\n2106:\tstatic int tcf_add_notify(struct net *net, struct nlmsghdr *n,\n2107:\t\t\t\t struct tc_action *actions[], u32 portid,\n2108:\t\t\t\t size_t attr_size, struct netlink_ext_ack *extack)\n2109:\t{\n2110:\t\tstruct sk_buff *skb;\n2111:\t\n2112:\t\tif (!rtnl_notify_needed(net, n-\u003enlmsg_flags, RTNLGRP_TC)) {\n2113:\t\t\tskb = NULL;\n2114:\t\t} else {\n2115:\t\t\tskb = tcf_add_notify_msg(net, n, actions, portid, attr_size,\n2116:\t\t\t\t\t\t extack);\n2117:\t\t\tif (IS_ERR(skb))\n2118:\t\t\t\treturn PTR_ERR(skb);\n2119:\t\t}\n"
} |
| 11/2 | 2026/09/22 05:23 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 9611 output: 32 thoughts: 301 Thoughts: **Analyzing this Patch: Network Scheduler Action Size Adjustments** Okay, let's dive into what's happening with this patch. My immediate impression is that we're dealing with adjustments to the size calculations for various network scheduler actions. I see a few key areas of modification. First, I note the addition of `tcf_action_warn_attr_size(extack)` in `net/sched/act_api.c`. This suggests we're now accounting for potential extended ACKs when handling messages related to adding and deleting traffic control filters (`tcf_del_notify_msg` and `tcf_add_notify_msg`). That makes sense, handling potential errors and warnings, ensuring sufficient buffer allocation. Then, there's a pattern emerging: several new functions are being implemented – `tcf_connmark_get_fill_size`, `tcf_mpls_get_fill_size`, `tcf_nat_get_fill_size`, `tcf_simp_get_fill_size`, and `tcf_skbmod_get_fill_size` across the respective action modules. It's clear these are all about determining the necessary size for filling out data structures associated with these actions. I also see that `tcf_mirred_get_fill_size` in `net/sched/act_mirred.c` is being updated to include `TCA_MIRRED_BLOCKID`. So, the common thread here is this `get_fill_size` function, and it seems to be tightly coupled with the way we report action sizes. Makes me wonder where these specific size calculations are used... Ah, right, they're being called within `tcf_action_fill_size(act)`. Now I need to see where this `tcf_action_fill_size` function is actually being *used*. That will tell me the bigger picture of where these adjustments are being integrated. |
| 12/2 | 2026/09/22 05:23 | tool | grepper |
0mArgs:{
"Expression": "tcf_action_fill_size",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=479=static size_t tcf_action_warn_attr_size(const struct netlink_ext_ack *extack)\n--\nnet/sched/act_api.c-486-\nnet/sched/act_api.c:487:static size_t tcf_action_fill_size(const struct tc_action *act)\nnet/sched/act_api.c-488-{\n--\nnet/sched/act_api.c=1487=int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla,\n--\nnet/sched/act_api.c-1534-\t\t}\nnet/sched/act_api.c:1535:\t\tsz += tcf_action_fill_size(act);\nnet/sched/act_api.c-1536-\t\t/* Start from index 0 */\n--\nnet/sched/act_api.c=1876=static struct sk_buff *tcf_reoffload_del_notify_msg(struct net *net,\n--\nnet/sched/act_api.c-1884-\nnet/sched/act_api.c:1885:\tattr_size = tcf_action_full_attrs_size(tcf_action_fill_size(action));\nnet/sched/act_api.c-1886-\n--\nnet/sched/act_api.c=2036=tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-2063-\t\t}\nnet/sched/act_api.c:2064:\t\tattr_size += tcf_action_fill_size(act);\nnet/sched/act_api.c-2065-\t\tactions[i - 1] = act;\n"
} |
| 13/2 | 2026/09/22 05:23 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 10842 output: 30 thoughts: 161 Thoughts: **Analyzing Potential Overflow Vulnerabilities in Netlink Attribute Handling** Okay, here's what I'm seeing. Whenever `tcf_action_init`, `tca_action_gd`, `tcf_del_notify_msg`, or `tcf_add_notify_msg` are invoked, `tcf_action_fill_size(act)` kicks in. It's job is to calculate the necessary buffer size for constructing the action notification message within an skb. I've noticed a potential vulnerability here. Historically, if `get_fill_size` was either absent or, more likely, if its calculation was too conservative, or if we were seeing extack warning messages, the allocated skb buffer was at risk of being undersized. This could manifest as problems when the netlink attributes are dumped in `tca_get_fill()`. I'm now especially focused on `tca_get_fill()`. My main concern is what happens if this function fails, or if it causes an overflow. I need to understand the implications of those conditions in this context. Is there error handling? Does it lead to a crash? Is there a subtle data corruption vulnerability, or some other potential for exploitation? This is where I want to focus my efforts. |
| 14/2 | 2026/09/22 05:23 | tool | grepper |
0mArgs:{
"Expression": "tca_get_fill",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=470=static size_t tcf_action_full_attrs_size(size_t sz)\n--\nnet/sched/act_api.c-477-\nnet/sched/act_api.c:478:/* tca_get_fill() may append TCA_ROOT_EXT_WARN_MSG from extack-\u003e_msg */\nnet/sched/act_api.c-479-static size_t tcf_action_warn_attr_size(const struct netlink_ext_ack *extack)\n--\nnet/sched/act_api.c=1617=int tcf_action_copy_stats(struct sk_buff *skb, struct tc_action *p,\n--\nnet/sched/act_api.c-1667-\nnet/sched/act_api.c:1668:static int tca_get_fill(struct sk_buff *skb, struct tc_action *actions[],\nnet/sched/act_api.c-1669-\t\t\tu32 portid, u32 seq, u16 flags, int event, int bind,\n--\nnet/sched/act_api.c=1708=tcf_get_notify(struct net *net, u32 portid, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-1716-\t\treturn -ENOBUFS;\nnet/sched/act_api.c:1717:\tif (tca_get_fill(skb, actions, portid, n-\u003enlmsg_seq, 0, event,\nnet/sched/act_api.c-1718-\t\t\t 0, 1, NULL) \u003c= 0) {\n--\nnet/sched/act_api.c=1876=static struct sk_buff *tcf_reoffload_del_notify_msg(struct net *net,\n--\nnet/sched/act_api.c-1890-\nnet/sched/act_api.c:1891:\tif (tca_get_fill(skb, actions, 0, 0, 0, RTM_DELACTION, 0, 1, NULL) \u003c= 0) {\nnet/sched/act_api.c-1892-\t\tkfree_skb(skb);\n--\nnet/sched/act_api.c=1985=static struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-1996-\nnet/sched/act_api.c:1997:\tif (tca_get_fill(skb, actions, portid, n-\u003enlmsg_seq, 0, RTM_DELACTION,\nnet/sched/act_api.c-1998-\t\t\t 0, 2, extack) \u003c= 0) {\n--\nnet/sched/act_api.c=2084=static struct sk_buff *tcf_add_notify_msg(struct net *net, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-2095-\nnet/sched/act_api.c:2096:\tif (tca_get_fill(skb, actions, portid, n-\u003enlmsg_seq, n-\u003enlmsg_flags,\nnet/sched/act_api.c-2097-\t\t\t RTM_NEWACTION, 0, 0, extack) \u003c= 0) {\n"
} |
| 15/2 | 2026/09/22 05:23 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 12172 output: 38 thoughts: 24 Thoughts: Here's my summary, as if I were thinking these thoughts: **Diving into the `tca_get_fill` Function** Okay, time to get into the weeds. Let's start by digging into `net/sched/act_api.c`. Specifically, I want to take a look at the `tca_get_fill` function. It's a key piece of the puzzle, and I'm interested in understanding how it's implemented. I'm expecting this to be the function responsible for populating the traffic control (TC) action attributes or data structures. I'll be looking for how it handles different action types, parses the user space data, and prepares it for the kernel's internal representation. I need to refresh my memory on the TC action infrastructure to interpret the purpose of the `tca_get_fill` function. I'm anticipating that it will handle populating the struct `tc_action` with information from a Netlink message. My focus will be on the parsing logic and the data structures involved. |
| 16/2 | 2026/09/22 05:23 | tool | read-file |
0mArgs:{
"File": "net/sched/act_api.c",
"FirstLine": 1665,
"LineCount": 45
}Results: {
"Contents": "1665:\t\treturn -1;\n1666:\t}\n1667:\t\n1668:\tstatic int tca_get_fill(struct sk_buff *skb, struct tc_action *actions[],\n1669:\t\t\t\tu32 portid, u32 seq, u16 flags, int event, int bind,\n1670:\t\t\t\tint ref, struct netlink_ext_ack *extack)\n1671:\t{\n1672:\t\tstruct tcamsg *t;\n1673:\t\tstruct nlmsghdr *nlh;\n1674:\t\tunsigned char *b = skb_tail_pointer(skb);\n1675:\t\tstruct nlattr *nest;\n1676:\t\n1677:\t\tnlh = nlmsg_put(skb, portid, seq, event, sizeof(*t), flags);\n1678:\t\tif (!nlh)\n1679:\t\t\tgoto out_nlmsg_trim;\n1680:\t\tt = nlmsg_data(nlh);\n1681:\t\tt-\u003etca_family = AF_UNSPEC;\n1682:\t\tt-\u003etca__pad1 = 0;\n1683:\t\tt-\u003etca__pad2 = 0;\n1684:\t\n1685:\t\tif (extack \u0026\u0026 extack-\u003e_msg \u0026\u0026\n1686:\t\t nla_put_string(skb, TCA_ROOT_EXT_WARN_MSG, extack-\u003e_msg))\n1687:\t\t\tgoto out_nlmsg_trim;\n1688:\t\n1689:\t\tnest = nla_nest_start_noflag(skb, TCA_ACT_TAB);\n1690:\t\tif (!nest)\n1691:\t\t\tgoto out_nlmsg_trim;\n1692:\t\n1693:\t\tif (tcf_action_dump(skb, actions, bind, ref, false) \u003c 0)\n1694:\t\t\tgoto out_nlmsg_trim;\n1695:\t\n1696:\t\tnla_nest_end(skb, nest);\n1697:\t\n1698:\t\tnlh-\u003enlmsg_len = skb_tail_pointer(skb) - b;\n1699:\t\n1700:\t\treturn skb-\u003elen;\n1701:\t\n1702:\tout_nlmsg_trim:\n1703:\t\tnlmsg_trim(skb, b);\n1704:\t\treturn -1;\n1705:\t}\n1706:\t\n1707:\tstatic int\n1708:\ttcf_get_notify(struct net *net, u32 portid, struct nlmsghdr *n,\n1709:\t\t struct tc_action *actions[], size_t attr_size, int event,\n"
} |
| 17/2 | 2026/09/22 05:23 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 13185 output: 34 thoughts: 24 Thoughts: Okay, here's my take on those thoughts, framed as an expert's internal monologue: **Investigating the Commit History** Alright, before I dive too deep into this patch, I need to get a better handle on the context. My first instinct is always to check the git history. Let's see what the commit message itself tells me. I'll fire up `git log` and see if there are any clues to be found within the commit messages or log entries. Hopefully, the author provided enough detail to understand the motivation behind the change and any related issues or discussions. This is usually the quickest way to grasp the "why" before I start digging into the "what." |
| 18/2 | 2026/09/22 05:24 | tool | grepper |
0mArgs:{
"Expression": "tcf_simp_get_fill_size",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_simple.c=61=static int reset_policy(struct tc_action *a, const struct nlattr *defdata,\n--\nnet/sched/act_simple.c-81-\nnet/sched/act_simple.c:82:static size_t tcf_simp_get_fill_size(const struct tc_action *act)\nnet/sched/act_simple.c-83-{\n--\nnet/sched/act_simple.c=207=static struct tc_action_ops act_simp_ops = {\n--\nnet/sched/act_simple.c-212-\t.dump\t\t=\ttcf_simp_dump,\nnet/sched/act_simple.c:213:\t.get_fill_size\t=\ttcf_simp_get_fill_size,\nnet/sched/act_simple.c-214-\t.cleanup\t=\ttcf_simp_release,\n"
} |
| 19/2 | 2026/09/22 05:24 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 13626 output: 27 thoughts: 107 Thoughts: **Kconfig Requirement Check** Alright, let's get down to brass tacks. I need to make sure these action files – `net/sched/act_api.c`, `net/sched/act_connmark.c`, `net/sched/act_mirred.c`, `net/sched/act_mpls.c`, `net/sched/act_nat.c`, `net/sched/act_simple.c`, and `net/sched/act_skbmod.c` – are configured correctly. First things first, I'll dive into the Kconfig for the networking scheduler. I'm going to need to scrutinize `net/sched/Kconfig` to see what configuration options are available and what dependencies they might have. It is essential to ensure they are set up as needed. I'll also glance over the `net/sched/Makefile` while I am there, just to get a lay of the land and see how these are built and linked. I know the drill; understanding the Kconfig context is key before I can even start thinking about the actual code changes. |
| 20/2 | 2026/09/22 05:24 | tool | grepper |
0mArgs:{
"Expression": "act_",
"PathPrefix": "net/sched/Makefile"
}Results: {
"Output": "net/sched/Makefile=10=obj-$(CONFIG_NET_CLS)\t\t+= cls_api.o\nnet/sched/Makefile:11:obj-$(CONFIG_NET_CLS_ACT)\t+= act_api.o\nnet/sched/Makefile:12:obj-$(CONFIG_NET_ACT_POLICE)\t+= act_police.o\nnet/sched/Makefile:13:obj-$(CONFIG_NET_ACT_GACT)\t+= act_gact.o\nnet/sched/Makefile:14:obj-$(CONFIG_NET_ACT_MIRRED)\t+= act_mirred.o\nnet/sched/Makefile:15:obj-$(CONFIG_NET_ACT_SAMPLE)\t+= act_sample.o\nnet/sched/Makefile:16:obj-$(CONFIG_NET_ACT_NAT)\t+= act_nat.o\nnet/sched/Makefile:17:obj-$(CONFIG_NET_ACT_PEDIT)\t+= act_pedit.o\nnet/sched/Makefile:18:obj-$(CONFIG_NET_ACT_SIMP)\t+= act_simple.o\nnet/sched/Makefile:19:obj-$(CONFIG_NET_ACT_SKBEDIT)\t+= act_skbedit.o\nnet/sched/Makefile:20:obj-$(CONFIG_NET_ACT_CSUM)\t+= act_csum.o\nnet/sched/Makefile:21:obj-$(CONFIG_NET_ACT_MPLS)\t+= act_mpls.o\nnet/sched/Makefile:22:obj-$(CONFIG_NET_ACT_VLAN)\t+= act_vlan.o\nnet/sched/Makefile:23:obj-$(CONFIG_NET_ACT_BPF)\t+= act_bpf.o\nnet/sched/Makefile:24:obj-$(CONFIG_NET_ACT_CONNMARK)\t+= act_connmark.o\nnet/sched/Makefile:25:obj-$(CONFIG_NET_ACT_CTINFO)\t+= act_ctinfo.o\nnet/sched/Makefile:26:obj-$(CONFIG_NET_ACT_SKBMOD)\t+= act_skbmod.o\nnet/sched/Makefile:27:obj-$(CONFIG_NET_ACT_IFE)\t+= act_ife.o\nnet/sched/Makefile:28:obj-$(CONFIG_NET_IFE_SKBMARK)\t+= act_meta_mark.o\nnet/sched/Makefile:29:obj-$(CONFIG_NET_IFE_SKBPRIO)\t+= act_meta_skbprio.o\nnet/sched/Makefile:30:obj-$(CONFIG_NET_IFE_SKBTCINDEX)\t+= act_meta_skbtcindex.o\nnet/sched/Makefile:31:obj-$(CONFIG_NET_ACT_TUNNEL_KEY)+= act_tunnel_key.o\nnet/sched/Makefile:32:obj-$(CONFIG_NET_ACT_CT)\t+= act_ct.o\nnet/sched/Makefile:33:obj-$(CONFIG_NET_ACT_GATE)\t+= act_gate.o\nnet/sched/Makefile-34-obj-$(CONFIG_NET_SCH_FIFO)\t+= sch_fifo.o\n"
} |
| 21/2 | 2026/09/22 05:24 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 14753 output: 31 thoughts: 15 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: **Investigating Network Scheduler Configuration Dependencies** Okay, so I need to understand the dependencies related to some network scheduler configuration. My initial move here is to dive directly into the `net/sched/Kconfig` file. That's the go-to location for kernel configuration options related to the networking scheduler subsystem. This Kconfig file will be the central source of truth for understanding how different scheduler options relate to each other, which features are conditional on others, and what architectural considerations influence their availability. The Kconfig syntax offers a clear and structured way to identify necessary prerequisites (like feature flags, hardware support, or other kernel modules). I'm looking to quickly identify the logical interconnections and configuration relationships. It's the most efficient way to understand the control flow, so I'm going there first. |
| 22/2 | 2026/09/22 05:24 | tool | grepper |
0mArgs:{
"Expression": "config NET_ACT_",
"PathPrefix": "net/sched/Kconfig"
}Results: {
"Output": "net/sched/Kconfig=702=config NET_CLS_ACT\n--\nnet/sched/Kconfig-714-\nnet/sched/Kconfig:715:config NET_ACT_POLICE\nnet/sched/Kconfig-716-\ttristate \"Traffic Policing\"\n--\nnet/sched/Kconfig-725-\nnet/sched/Kconfig:726:config NET_ACT_GACT\nnet/sched/Kconfig-727-\ttristate \"Generic actions\"\n--\nnet/sched/Kconfig=736=config GACT_PROB\n--\nnet/sched/Kconfig-741-\nnet/sched/Kconfig:742:config NET_ACT_MIRRED\nnet/sched/Kconfig-743-\ttristate \"Redirecting and Mirroring\"\n--\nnet/sched/Kconfig-751-\nnet/sched/Kconfig:752:config NET_ACT_SAMPLE\nnet/sched/Kconfig-753-\ttristate \"Traffic Sampling\"\n--\nnet/sched/Kconfig-763-\nnet/sched/Kconfig:764:config NET_ACT_NAT\nnet/sched/Kconfig-765-\ttristate \"Stateless NAT\"\n--\nnet/sched/Kconfig-773-\nnet/sched/Kconfig:774:config NET_ACT_PEDIT\nnet/sched/Kconfig-775-\ttristate \"Packet Editing\"\n--\nnet/sched/Kconfig-782-\nnet/sched/Kconfig:783:config NET_ACT_SIMP\nnet/sched/Kconfig-784-\ttristate \"Simple Example (Debug)\"\n--\nnet/sched/Kconfig-796-\nnet/sched/Kconfig:797:config NET_ACT_SKBEDIT\nnet/sched/Kconfig-798-\ttristate \"SKB Editing\"\n--\nnet/sched/Kconfig-807-\nnet/sched/Kconfig:808:config NET_ACT_CSUM\nnet/sched/Kconfig-809-\ttristate \"Checksum Updating\"\n--\nnet/sched/Kconfig-818-\nnet/sched/Kconfig:819:config NET_ACT_MPLS\nnet/sched/Kconfig-820-\ttristate \"MPLS manipulation\"\n--\nnet/sched/Kconfig-829-\nnet/sched/Kconfig:830:config NET_ACT_VLAN\nnet/sched/Kconfig-831-\ttristate \"Vlan manipulation\"\n--\nnet/sched/Kconfig-840-\nnet/sched/Kconfig:841:config NET_ACT_BPF\nnet/sched/Kconfig-842-\ttristate \"BPF based action\"\n--\nnet/sched/Kconfig-852-\nnet/sched/Kconfig:853:config NET_ACT_CONNMARK\nnet/sched/Kconfig-854-\ttristate \"Netfilter Connection Mark Retriever\"\n--\nnet/sched/Kconfig-864-\nnet/sched/Kconfig:865:config NET_ACT_CTINFO\nnet/sched/Kconfig-866-\ttristate \"Netfilter Connection Mark Actions\"\n--\nnet/sched/Kconfig-881-\nnet/sched/Kconfig:882:config NET_ACT_SKBMOD\nnet/sched/Kconfig-883-\ttristate \"skb data modification action\"\n--\nnet/sched/Kconfig-892-\nnet/sched/Kconfig:893:config NET_ACT_IFE\nnet/sched/Kconfig-894-\ttristate \"Inter-FE action based on IETF ForCES InterFE LFB\"\n--\nnet/sched/Kconfig-905-\nnet/sched/Kconfig:906:config NET_ACT_TUNNEL_KEY\nnet/sched/Kconfig-907-\ttristate \"IP tunnel metadata manipulation\"\n--\nnet/sched/Kconfig-916-\nnet/sched/Kconfig:917:config NET_ACT_CT\nnet/sched/Kconfig-918-\ttristate \"connection tracking tc action\"\n--\nnet/sched/Kconfig-929-\nnet/sched/Kconfig:930:config NET_ACT_GATE\nnet/sched/Kconfig-931-\ttristate \"Frame gate entry list control tc action\"\n"
} |
| 23/2 | 2026/09/22 05:24 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 16079 output: 34 thoughts: 63 Thoughts: Here's my take on the dependencies, thinking through this: **Dependency Deep Dive** Okay, time to dig into the dependencies. I need to get a clear picture of how these kernel modules are connected. Let's start with `NET_ACT_CONNMARK`, `NET_ACT_MIRRED`, `NET_ACT_MPLS`, `NET_ACT_NAT`, `NET_ACT_SIMP`, `NET_ACT_SKBMOD`, and `NET_CLS_ACT`. I need to figure out which ones rely on which, and if there are any significant implications for enabling or disabling them. This could involve looking at various configuration options, examining header files, and possibly even tracing the code if the dependencies aren't immediately obvious from the Kconfig files. The inter-dependencies are going to dictate the behavior of our networking stack. We need to be aware of how they relate. This is critical for getting the behavior we need, and not introducing any unexpected conflicts. I'm going to map these out clearly. |
| 24/2 | 2026/09/22 05:24 | tool | read-file |
0mArgs:{
"File": "net/sched/Kconfig",
"FirstLine": 700,
"LineCount": 45
}Results: {
"Contents": " 700:\t\t module will be called em_ipt.\n 701:\t\n 702:\tconfig NET_CLS_ACT\n 703:\t\tbool \"Actions\"\n 704:\t\tselect NET_CLS\n 705:\t\tselect NET_XGRESS\n 706:\t\thelp\n 707:\t\t Say Y here if you want to use traffic control actions. Actions\n 708:\t\t get attached to classifiers and are invoked after a successful\n 709:\t\t classification. They are used to overwrite the classification\n 710:\t\t result, instantly drop or redirect packets, etc.\n 711:\t\n 712:\t\t A recent version of the iproute2 package is required to use\n 713:\t\t extended matches.\n 714:\t\n 715:\tconfig NET_ACT_POLICE\n 716:\t\ttristate \"Traffic Policing\"\n 717:\t\tdepends on NET_CLS_ACT\n 718:\t\thelp\n 719:\t\t Say Y here if you want to do traffic policing, i.e. strict\n 720:\t\t bandwidth limiting. This action replaces the existing policing\n 721:\t\t module.\n 722:\t\n 723:\t\t To compile this code as a module, choose M here: the\n 724:\t\t module will be called act_police.\n 725:\t\n 726:\tconfig NET_ACT_GACT\n 727:\t\ttristate \"Generic actions\"\n 728:\t\tdepends on NET_CLS_ACT\n 729:\t\thelp\n 730:\t\t Say Y here to take generic actions such as dropping and\n 731:\t\t accepting packets.\n 732:\t\n 733:\t\t To compile this code as a module, choose M here: the\n 734:\t\t module will be called act_gact.\n 735:\t\n 736:\tconfig GACT_PROB\n 737:\t\tbool \"Probability support\"\n 738:\t\tdepends on NET_ACT_GACT\n 739:\t\thelp\n 740:\t\t Say Y here to use the generic action randomly or deterministically.\n 741:\t\n 742:\tconfig NET_ACT_MIRRED\n 743:\t\ttristate \"Redirecting and Mirroring\"\n 744:\t\tdepends on NET_CLS_ACT\n"
} |
| 25/2 | 2026/09/22 05:24 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 17008 output: 34 thoughts: 25 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: **Analyzing Relevant Netfilter Action Modules** Okay, let's dive in. My immediate focus is on understanding the interaction and potential conflicts between these Netfilter action modules, specifically those around `NET_ACT_CONNMARK`, `NET_ACT_MPLS`, and related modules. I want to quickly evaluate how these might interact and how the packet flow might be affected, which will guide further deeper analysis. I'm thinking about the order of operations, the data structures used, and potential race conditions, or whether there is any possibility for the system to incorrectly operate due to misconfigured rulesets. |
| 26/2 | 2026/09/22 05:24 | tool | read-file |
0mArgs:{
"File": "net/sched/Kconfig",
"FirstLine": 760,
"LineCount": 45
}Results: {
"Contents": " 760:\t\n 761:\t\t To compile this code as a module, choose M here: the\n 762:\t\t module will be called act_sample.\n 763:\t\n 764:\tconfig NET_ACT_NAT\n 765:\t\ttristate \"Stateless NAT\"\n 766:\t\tdepends on NET_CLS_ACT\n 767:\t\thelp\n 768:\t\t Say Y here to do stateless NAT on IPv4 packets. You should use\n 769:\t\t netfilter for NAT unless you know what you are doing.\n 770:\t\n 771:\t\t To compile this code as a module, choose M here: the\n 772:\t\t module will be called act_nat.\n 773:\t\n 774:\tconfig NET_ACT_PEDIT\n 775:\t\ttristate \"Packet Editing\"\n 776:\t\tdepends on NET_CLS_ACT\n 777:\t\thelp\n 778:\t\t Say Y here if you want to mangle the content of packets.\n 779:\t\n 780:\t\t To compile this code as a module, choose M here: the\n 781:\t\t module will be called act_pedit.\n 782:\t\n 783:\tconfig NET_ACT_SIMP\n 784:\t\ttristate \"Simple Example (Debug)\"\n 785:\t\tdepends on NET_CLS_ACT\n 786:\t\thelp\n 787:\t\t Say Y here to add a simple action for demonstration purposes.\n 788:\t\t It is meant as an example and for debugging purposes. It will\n 789:\t\t print a configured policy string followed by the packet count\n 790:\t\t to the console for every packet that passes by.\n 791:\t\n 792:\t\t If unsure, say N.\n 793:\t\n 794:\t\t To compile this code as a module, choose M here: the\n 795:\t\t module will be called act_simple.\n 796:\t\n 797:\tconfig NET_ACT_SKBEDIT\n 798:\t\ttristate \"SKB Editing\"\n 799:\t\tdepends on NET_CLS_ACT\n 800:\t\thelp\n 801:\t\t Say Y here to change skb priority or queue_mapping settings.\n 802:\t\n 803:\t\t If unsure, say N.\n 804:\t\n"
} |
| 27/2 | 2026/09/22 05:24 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 17843 output: 34 thoughts: 29 Thoughts: Okay, here's my take on those thoughts, framed as if they're my own: **Initial Diagnostic Thoughts: Network Activity Modules** Alright, time to get my hands dirty. I'm thinking, where do we start troubleshooting this network issue? Let's drill down into some of the likely suspects within the network activity realm. My gut tells me we should check out how these modules are behaving: `NET_ACT_MPLS`, `NET_ACT_CONNMARK`, and `NET_ACT_SKBMOD`. These are the usual suspects when you're looking at traffic manipulation and policy enforcement, and they're crucial for understanding the overall data flow. I want to see what's happening at those levels. |
| 28/2 | 2026/09/22 05:24 | tool | read-file |
0mArgs:{
"File": "net/sched/Kconfig",
"FirstLine": 815,
"LineCount": 75
}Results: {
"Contents": " 815:\t\n 816:\t\t To compile this code as a module, choose M here: the\n 817:\t\t module will be called act_csum.\n 818:\t\n 819:\tconfig NET_ACT_MPLS\n 820:\t\ttristate \"MPLS manipulation\"\n 821:\t\tdepends on NET_CLS_ACT\n 822:\t\thelp\n 823:\t\t Say Y here to push or pop MPLS headers.\n 824:\t\n 825:\t\t If unsure, say N.\n 826:\t\n 827:\t\t To compile this code as a module, choose M here: the\n 828:\t\t module will be called act_mpls.\n 829:\t\n 830:\tconfig NET_ACT_VLAN\n 831:\t\ttristate \"Vlan manipulation\"\n 832:\t\tdepends on NET_CLS_ACT\n 833:\t\thelp\n 834:\t\t Say Y here to push or pop vlan headers.\n 835:\t\n 836:\t\t If unsure, say N.\n 837:\t\n 838:\t\t To compile this code as a module, choose M here: the\n 839:\t\t module will be called act_vlan.\n 840:\t\n 841:\tconfig NET_ACT_BPF\n 842:\t\ttristate \"BPF based action\"\n 843:\t\tdepends on NET_CLS_ACT\n 844:\t\thelp\n 845:\t\t Say Y here to execute BPF code on packets. The BPF code will decide\n 846:\t\t if the packet should be dropped or not.\n 847:\t\n 848:\t\t If unsure, say N.\n 849:\t\n 850:\t\t To compile this code as a module, choose M here: the\n 851:\t\t module will be called act_bpf.\n 852:\t\n 853:\tconfig NET_ACT_CONNMARK\n 854:\t\ttristate \"Netfilter Connection Mark Retriever\"\n 855:\t\tdepends on NET_CLS_ACT \u0026\u0026 NETFILTER\n 856:\t\tdepends on NF_CONNTRACK \u0026\u0026 NF_CONNTRACK_MARK\n 857:\t\thelp\n 858:\t\t Say Y here to allow retrieving of conn mark\n 859:\t\n 860:\t\t If unsure, say N.\n 861:\t\n 862:\t\t To compile this code as a module, choose M here: the\n 863:\t\t module will be called act_connmark.\n 864:\t\n 865:\tconfig NET_ACT_CTINFO\n 866:\t\ttristate \"Netfilter Connection Mark Actions\"\n 867:\t\tdepends on NET_CLS_ACT \u0026\u0026 NETFILTER\n 868:\t\tdepends on NF_CONNTRACK \u0026\u0026 NF_CONNTRACK_MARK\n 869:\t\thelp\n 870:\t\t Say Y here to allow transfer of a connmark stored information.\n 871:\t\t Current actions transfer connmark stored DSCP into\n 872:\t\t ipv4/v6 diffserv and/or to transfer connmark to packet\n 873:\t\t mark. Both are useful for restoring egress based marks\n 874:\t\t back onto ingress connections for qdisc priority mapping\n 875:\t\t purposes.\n 876:\t\n 877:\t\t If unsure, say N.\n 878:\t\n 879:\t\t To compile this code as a module, choose M here: the\n 880:\t\t module will be called act_ctinfo.\n 881:\t\n 882:\tconfig NET_ACT_SKBMOD\n 883:\t\ttristate \"skb data modification action\"\n 884:\t\tdepends on NET_CLS_ACT\n 885:\t\thelp\n 886:\t\t Say Y here to allow modification of skb data\n 887:\t\n 888:\t\t If unsure, say N.\n 889:\t\n"
} |
| 29/2 | 2026/09/22 05:24 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 19099 output: 31 thoughts: 21 Thoughts: Here's my take on those thoughts: **Checking Kernel Configuration Dependencies** Okay, time to dive into the kernel configuration. I need to make sure I understand the dependencies for `NET_CLS_ACT`. The obvious place to start is `net/sched/Kconfig`. This is where all the related configurations should be defined, and where I can get a clear picture of what other options or features need to be enabled for `NET_CLS_ACT` to function correctly. I'll need to look for any `depends on` statements, any conditional dependencies, and understand how it all links together within the larger scheduling framework. My focus will be on the direct and indirect relationships with other networking features. Once I have this map, I can better understand the implication of enabling this feature and the possible configurations that I'll need to consider. |
| 30/2 | 2026/09/22 05:24 | tool | grepper |
0mArgs:{
"Expression": "NET_CLS_ACT",
"PathPrefix": "net/sched/Kconfig"
}Results: {
"Output": "net/sched/Kconfig=347=config NET_SCH_INGRESS\nnet/sched/Kconfig-348-\ttristate \"Ingress/classifier-action Qdisc\"\nnet/sched/Kconfig:349:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-350-\tselect NET_XGRESS\n--\nnet/sched/Kconfig=690=config NET_EMATCH_IPT\n--\nnet/sched/Kconfig-701-\nnet/sched/Kconfig:702:config NET_CLS_ACT\nnet/sched/Kconfig-703-\tbool \"Actions\"\n--\nnet/sched/Kconfig=715=config NET_ACT_POLICE\nnet/sched/Kconfig-716-\ttristate \"Traffic Policing\"\nnet/sched/Kconfig:717:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-718-\thelp\n--\nnet/sched/Kconfig=726=config NET_ACT_GACT\nnet/sched/Kconfig-727-\ttristate \"Generic actions\"\nnet/sched/Kconfig:728:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-729-\thelp\n--\nnet/sched/Kconfig=742=config NET_ACT_MIRRED\nnet/sched/Kconfig-743-\ttristate \"Redirecting and Mirroring\"\nnet/sched/Kconfig:744:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-745-\thelp\n--\nnet/sched/Kconfig=752=config NET_ACT_SAMPLE\nnet/sched/Kconfig-753-\ttristate \"Traffic Sampling\"\nnet/sched/Kconfig:754:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-755-\tselect PSAMPLE\n--\nnet/sched/Kconfig=764=config NET_ACT_NAT\nnet/sched/Kconfig-765-\ttristate \"Stateless NAT\"\nnet/sched/Kconfig:766:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-767-\thelp\n--\nnet/sched/Kconfig=774=config NET_ACT_PEDIT\nnet/sched/Kconfig-775-\ttristate \"Packet Editing\"\nnet/sched/Kconfig:776:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-777-\thelp\n--\nnet/sched/Kconfig=783=config NET_ACT_SIMP\nnet/sched/Kconfig-784-\ttristate \"Simple Example (Debug)\"\nnet/sched/Kconfig:785:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-786-\thelp\n--\nnet/sched/Kconfig=797=config NET_ACT_SKBEDIT\nnet/sched/Kconfig-798-\ttristate \"SKB Editing\"\nnet/sched/Kconfig:799:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-800-\thelp\n--\nnet/sched/Kconfig=808=config NET_ACT_CSUM\nnet/sched/Kconfig-809-\ttristate \"Checksum Updating\"\nnet/sched/Kconfig:810:\tdepends on NET_CLS_ACT \u0026\u0026 INET\nnet/sched/Kconfig-811-\tselect NET_CRC32C\n--\nnet/sched/Kconfig=819=config NET_ACT_MPLS\nnet/sched/Kconfig-820-\ttristate \"MPLS manipulation\"\nnet/sched/Kconfig:821:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-822-\thelp\n--\nnet/sched/Kconfig=830=config NET_ACT_VLAN\nnet/sched/Kconfig-831-\ttristate \"Vlan manipulation\"\nnet/sched/Kconfig:832:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-833-\thelp\n--\nnet/sched/Kconfig=841=config NET_ACT_BPF\nnet/sched/Kconfig-842-\ttristate \"BPF based action\"\nnet/sched/Kconfig:843:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-844-\thelp\n--\nnet/sched/Kconfig=853=config NET_ACT_CONNMARK\nnet/sched/Kconfig-854-\ttristate \"Netfilter Connection Mark Retriever\"\nnet/sched/Kconfig:855:\tdepends on NET_CLS_ACT \u0026\u0026 NETFILTER\nnet/sched/Kconfig-856-\tdepends on NF_CONNTRACK \u0026\u0026 NF_CONNTRACK_MARK\n--\nnet/sched/Kconfig=865=config NET_ACT_CTINFO\nnet/sched/Kconfig-866-\ttristate \"Netfilter Connection Mark Actions\"\nnet/sched/Kconfig:867:\tdepends on NET_CLS_ACT \u0026\u0026 NETFILTER\nnet/sched/Kconfig-868-\tdepends on NF_CONNTRACK \u0026\u0026 NF_CONNTRACK_MARK\n--\nnet/sched/Kconfig=882=config NET_ACT_SKBMOD\nnet/sched/Kconfig-883-\ttristate \"skb data modification action\"\nnet/sched/Kconfig:884:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-885-\thelp\n--\nnet/sched/Kconfig=893=config NET_ACT_IFE\nnet/sched/Kconfig-894-\ttristate \"Inter-FE action based on IETF ForCES InterFE LFB\"\nnet/sched/Kconfig:895:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-896-\tselect NET_IFE\n--\nnet/sched/Kconfig=906=config NET_ACT_TUNNEL_KEY\nnet/sched/Kconfig-907-\ttristate \"IP tunnel metadata manipulation\"\nnet/sched/Kconfig:908:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-909-\thelp\n--\nnet/sched/Kconfig=917=config NET_ACT_CT\nnet/sched/Kconfig-918-\ttristate \"connection tracking tc action\"\nnet/sched/Kconfig:919:\tdepends on NET_CLS_ACT \u0026\u0026 NF_CONNTRACK \u0026\u0026 (!NF_NAT || NF_NAT) \u0026\u0026 NF_FLOW_TABLE\nnet/sched/Kconfig-920-\tselect NF_CONNTRACK_OVS\n--\nnet/sched/Kconfig=930=config NET_ACT_GATE\nnet/sched/Kconfig-931-\ttristate \"Frame gate entry list control tc action\"\nnet/sched/Kconfig:932:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-933-\thelp\n--\nnet/sched/Kconfig=954=config NET_TC_SKB_EXT\nnet/sched/Kconfig-955-\tbool \"TC recirculation support\"\nnet/sched/Kconfig:956:\tdepends on NET_CLS_ACT\nnet/sched/Kconfig-957-\tselect SKB_EXTENSIONS\n"
} |
| 31/2 | 2026/09/22 05:24 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 21108 output: 32 thoughts: 45 Thoughts: Here's my take on those thoughts: **Analyzing Kernel Configuration Dependencies** Okay, so I'm looking at how the kernel's network classification and actions are wired together. Specifically, I'm noting that enabling `NET_CLS_ACT` automatically pulls in both `NET_CLS` and `NET_XGRESS`. This tells me immediately that classification actions are intrinsically linked to core classification mechanisms and potentially some network ingress/egress components. Now, to understand the broader context and potential implications of these dependencies, I need to dig deeper. My next logical step is to examine the `net/sched/Kconfig` file. I need to see what other options are defined there, and specifically, what options might be required or are set as defaults. That should give me a good lay of the land, revealing the potential scope of these interdependencies. I'm especially interested in dependencies upstream to `NET_CLS`, `NET_XGRESS`, and `NET_CLS_ACT` and what other subsystems it may relate to. |
| 32/2 | 2026/09/22 05:24 | tool | read-file |
0mArgs:{
"File": "net/sched/Kconfig",
"FirstLine": 1,
"LineCount": 25
}Results: {
"Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0-only\n 2:\t#\n 3:\t# Traffic control configuration.\n 4:\t#\n 5:\t\n 6:\tmenuconfig NET_SCHED\n 7:\t\tbool \"QoS and/or fair queueing\"\n 8:\t\tselect NET_SCH_FIFO\n 9:\t\thelp\n 10:\t\t When the kernel has several packets to send out over a network\n 11:\t\t device, it has to decide which ones to send first, which ones to\n 12:\t\t delay, and which ones to drop. This is the job of the queueing\n 13:\t\t disciplines, several different algorithms for how to do this\n 14:\t\t \"fairly\" have been proposed.\n 15:\t\n 16:\t\t If you say N here, you will get the standard packet scheduler, which\n 17:\t\t is a FIFO (first come, first served). If you say Y here, you will be\n 18:\t\t able to choose from among several alternative algorithms which can\n 19:\t\t then be attached to different network devices. This is useful for\n 20:\t\t example if some of your network devices are real time devices that\n 21:\t\t need a certain minimum data flow rate, or if you need to limit the\n 22:\t\t maximum data flow rate for traffic which matches specified criteria.\n 23:\t\t This code is considered to be experimental.\n 24:\t\n 25:\t\t To administer these schedulers, you'll need the user-level utilities\n"
} |
| 33/2 | 2026/09/22 05:24 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 21793 output: 35 thoughts: 1136 Thoughts: **Fuzzing Potential: Traffic Control Action Size Calculations** Okay, let's break this down. It looks like we're dealing with a patch related to traffic control actions within the networking stack. Specifically, it seems to be about how the kernel calculates buffer sizes when dealing with netlink messages for these actions. The core of this hinges around the `NET_SCHED` config option, which enables the whole shebang, and then all the dependencies: `NET_CLS_ACT` and specific actions like `act_connmark`, `act_mirred`, etc. The question is, *is this worth fuzzing?* And the answer, at least based on this initial assessment, is a resounding *yes*. Here's the reasoning: 1. **Reachable? Absolutely.** Traffic control actions are prime targets via rtnetlink (`RTM_NEWACTION`, `RTM_DELACTION`, etc.), which Syzkaller already exercises heavily. That's a huge win for usability. 2. **Kernel Code? Check.** This isn't some user-space utility. It's deep in `net/sched/`, kernel C code, so we have the opportunity to trigger all kinds of nasty issues. 3. **Hardware Unrelated? Correct.** It's purely virtual networking, so we don't need any special hardware setup, avoiding a huge development cost. 4. **Buffer Size Calculations? Bingo!** This patch directly alters how buffer sizes are calculated for netlink messages. We are talking about `tcf_action_warn_attr_size`, `.get_fill_size` for all the relevant action types (connmark, mirred, mpls, nat, simple, skbmod), and how `tcf_del_notify_msg` and `tcf_add_notify_msg` behave. These are the money spots for buffer overflows, truncation, and allocation issues, all of which are juicy for fuzzing, and very dangerous if there's a problem. Now, let's determine the relevant FocusSymbols so we can target our fuzzing efforts precisely. The crucial symbols seem to be within `net/sched/act_api.c`: * `tcf_action_warn_attr_size` * `tcf_del_notify_msg` * `tcf_add_notify_msg` I need to confirm whether these are inlined or exported or called by other functions. If they're static and inlined, they won't have individual symbols. However, I have noticed that functions like `tcf_connmark_get_fill_size`, `tcf_mirred_get_fill_size`, etc. are stored as function pointers within the `struct tc_action_ops`. Because these are function pointers, the compiler *cannot* inline them. They *must* have distinct symbol addresses! This makes them perfect fuzzing targets, especially since they're involved in calculating sizes. So, the following functions should be added as FocusSymbols: * `tcf_connmark_get_fill_size` * `tcf_mirred_get_fill_size` * `tcf_mpls_get_fill_size` * `tcf_nat_get_fill_size` * `tcf_simp_get_fill_size` * `tcf_skbmod_get_fill_size` We will need to double-check callers of `tcf_del_notify_msg` and `tcf_add_notify_msg`, though, to see if they're also interesting, but I think that is enough to kick things off. |
| 34/2 | 2026/09/22 05:24 | tool | grepper |
0mArgs:{
"Expression": "tcf_del_notify",
"PathPrefix": "net/sched/act_api.c"
}Results: {
"Output": "net/sched/act_api.c=1927=int tcf_action_reoffload_cb(flow_indr_block_bind_cb_t *cb,\n--\nnet/sched/act_api.c-1984-\nnet/sched/act_api.c:1985:static struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,\nnet/sched/act_api.c-1986-\t\t\t\t\t struct tc_action *actions[],\n--\nnet/sched/act_api.c-2006-\nnet/sched/act_api.c:2007:static int tcf_del_notify(struct net *net, struct nlmsghdr *n,\nnet/sched/act_api.c-2008-\t\t\t struct tc_action *actions[], u32 portid,\n--\nnet/sched/act_api.c-2016-\t} else {\nnet/sched/act_api.c:2017:\t\tskb = tcf_del_notify_msg(net, n, actions, portid, attr_size,\nnet/sched/act_api.c-2018-\t\t\t\t\t extack);\n--\nnet/sched/act_api.c=2036=tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-2073-\telse { /* delete */\nnet/sched/act_api.c:2074:\t\tret = tcf_del_notify(net, n, actions, portid, attr_size, extack);\nnet/sched/act_api.c-2075-\t\tif (ret)\n"
} |
| 35/2 | 2026/09/22 05:24 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 24196 output: 35 thoughts: 26 Thoughts: Okay, here's my interpretation of those thoughts, summarized from a first-person expert perspective: **Deep Dive into Notification Mechanisms** Alright, so we need to get a really good handle on what's triggering these notifications. Specifically, I need to investigate the call sites of `tcf_add_notify` and `tcf_add_notify_msg`. I'm going to look at those function calls to see where they are being called from. I need to trace the flow of control and data to understand the context in which these notification functions are used. This will reveal the events or conditions that prompt these notifications and which functions or parts of the system are relying on them. This will provide some greater context for the work at hand. |
| 36/2 | 2026/09/22 05:24 | tool | grepper |
0mArgs:{
"Expression": "tcf_add_notify",
"PathPrefix": "net/sched/act_api.c"
}Results: {
"Output": "net/sched/act_api.c=2036=tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-2083-\nnet/sched/act_api.c:2084:static struct sk_buff *tcf_add_notify_msg(struct net *net, struct nlmsghdr *n,\nnet/sched/act_api.c-2085-\t\t\t\t\t struct tc_action *actions[],\n--\nnet/sched/act_api.c-2105-\nnet/sched/act_api.c:2106:static int tcf_add_notify(struct net *net, struct nlmsghdr *n,\nnet/sched/act_api.c-2107-\t\t\t struct tc_action *actions[], u32 portid,\n--\nnet/sched/act_api.c-2114-\t} else {\nnet/sched/act_api.c:2115:\t\tskb = tcf_add_notify_msg(net, n, actions, portid, attr_size,\nnet/sched/act_api.c-2116-\t\t\t\t\t extack);\n--\nnet/sched/act_api.c=2125=static int tcf_action_add(struct net *net, struct nlattr *nla,\n--\nnet/sched/act_api.c-2143-\nnet/sched/act_api.c:2144:\tret = tcf_add_notify(net, n, actions, portid, attr_size, extack);\nnet/sched/act_api.c-2145-\n"
} |
| 37/2 | 2026/09/22 05:24 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 24840 output: 30 thoughts: 402 Thoughts: **Analyzing Netlink Message Handling for Traffic Control Actions** Okay, so I'm digging into how these traffic control actions are managed, specifically focusing on the netlink message generation and handling. I'm starting with the notification messages. Right, so `tcf_del_notify_msg` is called by `tcf_del_notify`, and `tcf_add_notify_msg` is called by `tcf_add_notify`. And we've got `tca_action_gd` for handling `RTM_DELACTION` and `RTM_GETACTION` netlink requests, and `tcf_action_add` for `RTM_NEWACTION`. Plus, `tcf_action_fill_size` uses `ops->get_fill_size`. Now, the question is whether `tcf_add_notify_msg` and `tcf_del_notify_msg` are inlined anywhere. Even if they are inlined into their respective wrapper functions, `tcf_add_notify` and `tcf_del_notify` are still pretty direct feature functions. But, and this is important, `tcf_add_notify_msg` and `tcf_del_notify_msg` are modified directly. So there is a higher potential for error. We need to check those for sure. I should probably also have a look at `tcf_action_fill_size` as part of this. Alright, let's see what we've got in `net/sched/act_api.c`. Searching... Okay, here we go: `tcf_del_notify_msg`, `tcf_add_notify_msg`, and `tcf_action_fill_size` are all there, and then we have the specific size helpers: `tcf_connmark_get_fill_size`, `tcf_mirred_get_fill_size`, `tcf_mpls_get_fill_size`, `tcf_nat_get_fill_size`, `tcf_simp_get_fill_size`, and `tcf_skbmod_get_fill_size`. Seems like a pretty good list to start with. Hold on a sec, I need to zoom out a bit. Are `tca_action_gd` or `tc_ctl_action` the *main* entry points for these netlink calls? That's the real question. Let's make sure we've got the top-level calls right. This is where the whole thing starts! |
| 38/2 | 2026/09/22 05:24 | tool | grepper |
0mArgs:{
"Expression": "tca_action_gd",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=2035=static int\nnet/sched/act_api.c:2036:tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,\nnet/sched/act_api.c-2037-\t u32 portid, int event, struct netlink_ext_ack *extack)\n--\nnet/sched/act_api.c=2158=static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-2195-\tcase RTM_DELACTION:\nnet/sched/act_api.c:2196:\t\tret = tca_action_gd(net, tca[TCA_ACT_TAB], n,\nnet/sched/act_api.c-2197-\t\t\t\t portid, RTM_DELACTION, extack);\n--\nnet/sched/act_api.c-2199-\tcase RTM_GETACTION:\nnet/sched/act_api.c:2200:\t\tret = tca_action_gd(net, tca[TCA_ACT_TAB], n,\nnet/sched/act_api.c-2201-\t\t\t\t portid, RTM_GETACTION, extack);\n"
} |
| 39/2 | 2026/09/22 05:24 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 26164 output: 38 thoughts: 58 Thoughts: Here's my summary, as though I'm thinking through this process: **Diving into the `tc_ctl_action` Handler** Okay, so I'm focusing on the netlink handler `tc_ctl_action`. It handles the `RTM_NEWACTION`, `RTM_DELACTION`, and `RTM_GETACTION` requests. My immediate interest is in what this handler *does* for `RTM_NEWACTION`. Time to dig in and see how it processes a request to create a new action within the traffic control system. I need to understand how this function is structured, what data it parses from the netlink message, and how it translates that into the actual instantiation of a new traffic control action. It should be interesting to see how it handles things like object creation, error checking, and attribute processing. |
| 40/2 | 2026/09/22 05:25 | tool | read-file |
0mArgs:{
"File": "net/sched/act_api.c",
"FirstLine": 2175,
"LineCount": 35
}Results: {
"Contents": "2175:\t\n2176:\t\tif (tca[TCA_ACT_TAB] == NULL) {\n2177:\t\t\tNL_SET_ERR_MSG(extack, \"Netlink action attributes missing\");\n2178:\t\t\treturn -EINVAL;\n2179:\t\t}\n2180:\t\n2181:\t\t/* n-\u003enlmsg_flags \u0026 NLM_F_CREATE */\n2182:\t\tswitch (n-\u003enlmsg_type) {\n2183:\t\tcase RTM_NEWACTION:\n2184:\t\t\t/* we are going to assume all other flags\n2185:\t\t\t * imply create only if it doesn't exist\n2186:\t\t\t * Note that CREATE | EXCL implies that\n2187:\t\t\t * but since we want avoid ambiguity (eg when flags\n2188:\t\t\t * is zero) then just set this\n2189:\t\t\t */\n2190:\t\t\tif (n-\u003enlmsg_flags \u0026 NLM_F_REPLACE)\n2191:\t\t\t\tflags = TCA_ACT_FLAGS_REPLACE;\n2192:\t\t\tret = tcf_action_add(net, tca[TCA_ACT_TAB], n, portid, flags,\n2193:\t\t\t\t\t extack);\n2194:\t\t\tbreak;\n2195:\t\tcase RTM_DELACTION:\n2196:\t\t\tret = tca_action_gd(net, tca[TCA_ACT_TAB], n,\n2197:\t\t\t\t\t portid, RTM_DELACTION, extack);\n2198:\t\t\tbreak;\n2199:\t\tcase RTM_GETACTION:\n2200:\t\t\tret = tca_action_gd(net, tca[TCA_ACT_TAB], n,\n2201:\t\t\t\t\t portid, RTM_GETACTION, extack);\n2202:\t\t\tbreak;\n2203:\t\tdefault:\n2204:\t\t\tBUG();\n2205:\t\t}\n2206:\t\n2207:\t\treturn ret;\n2208:\t}\n2209:\t\n"
} |
| 41/2 | 2026/09/22 05:25 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 26979 output: 38 thoughts: 15 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: **Investigating `tcf_action_add`** Okay, so we've looked at the primary component, but a potential edge case that's immediately calling out for review is the handling of additions within the TCF framework. I need to pivot and dive into how `tcf_action_add` specifically functions. Given my understanding of the system's architecture, I anticipate certain interactions – are the add operations atomic? What's the impact on data consistency during concurrent access? How does it interact with the general transaction flow, if at all? This has implications for potential race conditions, deadlock scenarios, or even unintended data corruption if the implementation is sloppy. I need to trace this specific function to ensure it's not a source of vulnerabilities or errors. Let's see how it plays out. |
| 42/2 | 2026/09/22 05:25 | tool | read-file |
0mArgs:{
"File": "net/sched/act_api.c",
"FirstLine": 2125,
"LineCount": 35
}Results: {
"Contents": "2125:\tstatic int tcf_action_add(struct net *net, struct nlattr *nla,\n2126:\t\t\t\t struct nlmsghdr *n, u32 portid, u32 flags,\n2127:\t\t\t\t struct netlink_ext_ack *extack)\n2128:\t{\n2129:\t\tsize_t attr_size = 0;\n2130:\t\tint loop, ret;\n2131:\t\tstruct tc_action *actions[TCA_ACT_MAX_PRIO] = {};\n2132:\t\tint init_res[TCA_ACT_MAX_PRIO] = {};\n2133:\t\n2134:\t\tfor (loop = 0; loop \u003c 10; loop++) {\n2135:\t\t\tret = tcf_action_init(net, NULL, nla, NULL, actions, init_res,\n2136:\t\t\t\t\t \u0026attr_size, flags, 0, extack);\n2137:\t\t\tif (ret != -EAGAIN)\n2138:\t\t\t\tbreak;\n2139:\t\t}\n2140:\t\n2141:\t\tif (ret \u003c 0)\n2142:\t\t\treturn ret;\n2143:\t\n2144:\t\tret = tcf_add_notify(net, n, actions, portid, attr_size, extack);\n2145:\t\n2146:\t\t/* only put bound actions */\n2147:\t\ttca_put_bound_many(actions, init_res);\n2148:\t\n2149:\t\treturn ret;\n2150:\t}\n2151:\t\n2152:\tstatic const struct nla_policy tcaa_policy[TCA_ROOT_MAX + 1] = {\n2153:\t\t[TCA_ROOT_FLAGS] = NLA_POLICY_BITFIELD32(TCA_ACT_FLAG_LARGE_DUMP_ON |\n2154:\t\t\t\t\t\t\t TCA_ACT_FLAG_TERSE_DUMP),\n2155:\t\t[TCA_ROOT_TIME_DELTA] = { .type = NLA_U32 },\n2156:\t};\n2157:\t\n2158:\tstatic int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n,\n2159:\t\t\t\t struct netlink_ext_ack *extack)\n"
} |
| 43/2 | 2026/09/22 05:25 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 27834 output: 29 thoughts: 398 Thoughts: **Analyzing the Action Module Size Calculation** Okay, let's break down this `tc_ctl_action` flow. When we're handling `RTM_NEWACTION`, we're going through `tcf_action_add`, which then calls `tcf_action_init`. Within `tcf_action_init`, we've got an iteration over the actions, and the size calculation is done with `sz += tcf_action_fill_size(act)`. This function is really important because it calls `act->ops->get_fill_size(act)`. That's where the action-specific size calculation happens. The addition notification side (`tcf_add_notify` -> `tcf_add_notify_msg`) calls `alloc_skb` to allocate a buffer with a size of `max(attr_size + tcf_action_warn_attr_size(extack), NLMSG_GOODSIZE)`. It uses `tca_get_fill` to actually write the data into the buffer. The deletion path (`RTM_DELACTION`) looks similar. We go through `tca_action_gd` and then we iterate over actions. We again do the size calculation: `attr_size += tcf_action_fill_size(act)`, and the notification path goes through `tcf_del_notify` -> `tcf_del_notify_msg`. The buffer allocation calls `alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack), NLMSG_GOODSIZE))` and uses `tca_get_fill`. The crucial bit, of course, is that these specific actions have their own implementations for `.get_fill_size`. I see those listed here: `tcf_connmark_get_fill_size`, `tcf_mirred_get_fill_size`, `tcf_mpls_get_fill_size`, `tcf_nat_get_fill_size`, `tcf_simp_get_fill_size`, and `tcf_skbmod_get_fill_size`. I should check `net/sched/` to confirm that there aren't any other implementations that I missed. This gives a pretty good overview of how the size of these actions is determined. |
| 44/2 | 2026/09/22 05:25 | tool | grepper |
0mArgs:{
"Expression": "get_fill_size",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=487=static size_t tcf_action_fill_size(const struct tc_action *act)\n--\nnet/sched/act_api.c-490-\nnet/sched/act_api.c:491:\tif (act-\u003eops-\u003eget_fill_size)\nnet/sched/act_api.c:492:\t\treturn act-\u003eops-\u003eget_fill_size(act) + sz;\nnet/sched/act_api.c-493-\treturn sz;\n--\nnet/sched/act_bpf.c=384=static void tcf_bpf_cleanup(struct tc_action *act)\n--\nnet/sched/act_bpf.c-391-\nnet/sched/act_bpf.c:392:static size_t tcf_bpf_get_fill_size(const struct tc_action *act)\nnet/sched/act_bpf.c-393-{\n--\nnet/sched/act_bpf.c=417=static struct tc_action_ops act_bpf_ops __read_mostly = {\n--\nnet/sched/act_bpf.c-424-\t.init\t\t=\ttcf_bpf_init,\nnet/sched/act_bpf.c:425:\t.get_fill_size\t=\ttcf_bpf_get_fill_size,\nnet/sched/act_bpf.c-426-\t.size\t\t=\tsizeof(struct tcf_bpf),\n--\nnet/sched/act_connmark.c=229=static void tcf_connmark_cleanup(struct tc_action *a)\n--\nnet/sched/act_connmark.c-238-\nnet/sched/act_connmark.c:239:static size_t tcf_connmark_get_fill_size(const struct tc_action *act)\nnet/sched/act_connmark.c-240-{\n--\nnet/sched/act_connmark.c=244=static struct tc_action_ops act_connmark_ops = {\n--\nnet/sched/act_connmark.c-249-\t.dump\t\t=\ttcf_connmark_dump,\nnet/sched/act_connmark.c:250:\t.get_fill_size\t=\ttcf_connmark_get_fill_size,\nnet/sched/act_connmark.c-251-\t.init\t\t=\ttcf_connmark_init,\n--\nnet/sched/act_csum.c=674=static void tcf_csum_cleanup(struct tc_action *a)\n--\nnet/sched/act_csum.c-683-\nnet/sched/act_csum.c:684:static size_t tcf_csum_get_fill_size(const struct tc_action *act)\nnet/sched/act_csum.c-685-{\n--\nnet/sched/act_csum.c=708=static struct tc_action_ops act_csum_ops = {\n--\nnet/sched/act_csum.c-715-\t.cleanup\t= tcf_csum_cleanup,\nnet/sched/act_csum.c:716:\t.get_fill_size = tcf_csum_get_fill_size,\nnet/sched/act_csum.c-717-\t.offload_act_setup = tcf_csum_offload_act_setup,\n--\nnet/sched/act_ct.c=1636=static int tcf_ct_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_ct.c-1659-\nnet/sched/act_ct.c:1660:static size_t tcf_ct_get_fill_size(const struct tc_action *act)\nnet/sched/act_ct.c-1661-{\n--\nnet/sched/act_ct.c=1705=static struct tc_action_ops act_ct_ops = {\n--\nnet/sched/act_ct.c-1713-\t.stats_update\t=\ttcf_stats_update,\nnet/sched/act_ct.c:1714:\t.get_fill_size\t=\ttcf_ct_get_fill_size,\nnet/sched/act_ct.c-1715-\t.offload_act_setup =\ttcf_ct_offload_act_setup,\n--\nnet/sched/act_ctinfo.c=349=static void tcf_ctinfo_cleanup(struct tc_action *a)\n--\nnet/sched/act_ctinfo.c-358-\nnet/sched/act_ctinfo.c:359:static size_t tcf_ctinfo_get_fill_size(const struct tc_action *act)\nnet/sched/act_ctinfo.c-360-{\n--\nnet/sched/act_ctinfo.c=369=static struct tc_action_ops act_ctinfo_ops = {\n--\nnet/sched/act_ctinfo.c-376-\t.cleanup= tcf_ctinfo_cleanup,\nnet/sched/act_ctinfo.c:377:\t.get_fill_size = tcf_ctinfo_get_fill_size,\nnet/sched/act_ctinfo.c-378-\t.size\t= sizeof(struct tcf_ctinfo),\n--\nnet/sched/act_gact.c=190=static int tcf_gact_dump(struct sk_buff *skb, struct tc_action *a,\n--\nnet/sched/act_gact.c-230-\nnet/sched/act_gact.c:231:static size_t tcf_gact_get_fill_size(const struct tc_action *act)\nnet/sched/act_gact.c-232-{\n--\nnet/sched/act_gact.c=292=static struct tc_action_ops act_gact_ops = {\n--\nnet/sched/act_gact.c-299-\t.init\t\t=\ttcf_gact_init,\nnet/sched/act_gact.c:300:\t.get_fill_size\t=\ttcf_gact_get_fill_size,\nnet/sched/act_gact.c-301-\t.offload_act_setup =\ttcf_gact_offload_act_setup,\n--\nnet/sched/act_gate.c=672=static void tcf_gate_stats_update(struct tc_action *a, u64 bytes, u64 packets,\n--\nnet/sched/act_gate.c-681-\nnet/sched/act_gate.c:682:static size_t tcf_gate_get_fill_size(const struct tc_action *act)\nnet/sched/act_gate.c-683-{\n--\nnet/sched/act_gate.c=736=static struct tc_action_ops act_gate_ops = {\n--\nnet/sched/act_gate.c-744-\t.stats_update\t=\ttcf_gate_stats_update,\nnet/sched/act_gate.c:745:\t.get_fill_size\t=\ttcf_gate_get_fill_size,\nnet/sched/act_gate.c-746-\t.offload_act_setup =\ttcf_gate_offload_act_setup,\n--\nnet/sched/act_ife.c=881=TC_INDIRECT_SCOPE int tcf_ife_act(struct sk_buff *skb,\n--\nnet/sched/act_ife.c-904-\nnet/sched/act_ife.c:905:static size_t tcf_ife_get_fill_size(const struct tc_action *act)\nnet/sched/act_ife.c-906-{\n--\nnet/sched/act_ife.c=927=static struct tc_action_ops act_ife_ops = {\n--\nnet/sched/act_ife.c-934-\t.init = tcf_ife_init,\nnet/sched/act_ife.c:935:\t.get_fill_size = tcf_ife_get_fill_size,\nnet/sched/act_ife.c-936-\t.size =\tsizeof(struct tcf_ife_info),\n--\nnet/sched/act_mirred.c=591=tcf_mirred_get_dev(const struct tc_action *a,\n--\nnet/sched/act_mirred.c-607-\nnet/sched/act_mirred.c:608:static size_t tcf_mirred_get_fill_size(const struct tc_action *act)\nnet/sched/act_mirred.c-609-{\n--\nnet/sched/act_mirred.c=665=static struct tc_action_ops act_mirred_ops = {\n--\nnet/sched/act_mirred.c-673-\t.init\t\t=\ttcf_mirred_init,\nnet/sched/act_mirred.c:674:\t.get_fill_size\t=\ttcf_mirred_get_fill_size,\nnet/sched/act_mirred.c-675-\t.offload_act_setup =\ttcf_mirred_offload_act_setup,\n--\nnet/sched/act_mpls.c=382=static int tcf_mpls_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_mpls.c-440-\nnet/sched/act_mpls.c:441:static size_t tcf_mpls_get_fill_size(const struct tc_action *act)\nnet/sched/act_mpls.c-442-{\n--\nnet/sched/act_mpls.c=451=static struct tc_action_ops act_mpls_ops = {\n--\nnet/sched/act_mpls.c-456-\t.dump\t\t=\ttcf_mpls_dump,\nnet/sched/act_mpls.c:457:\t.get_fill_size\t=\ttcf_mpls_get_fill_size,\nnet/sched/act_mpls.c-458-\t.init\t\t=\ttcf_mpls_init,\n--\nnet/sched/act_nat.c=306=static void tcf_nat_cleanup(struct tc_action *a)\n--\nnet/sched/act_nat.c-315-\nnet/sched/act_nat.c:316:static size_t tcf_nat_get_fill_size(const struct tc_action *act)\nnet/sched/act_nat.c-317-{\n--\nnet/sched/act_nat.c=321=static struct tc_action_ops act_nat_ops = {\n--\nnet/sched/act_nat.c-326-\t.dump\t\t=\ttcf_nat_dump,\nnet/sched/act_nat.c:327:\t.get_fill_size\t=\ttcf_nat_get_fill_size,\nnet/sched/act_nat.c-328-\t.init\t\t=\ttcf_nat_init,\n--\nnet/sched/act_pedit.c=564=static int tcf_pedit_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_pedit.c-628-\nnet/sched/act_pedit.c:629:static size_t tcf_pedit_get_fill_size(const struct tc_action *act)\nnet/sched/act_pedit.c-630-{\n--\nnet/sched/act_pedit.c=652=static struct tc_action_ops act_pedit_ops = {\n--\nnet/sched/act_pedit.c-660-\t.init\t\t=\ttcf_pedit_init,\nnet/sched/act_pedit.c:661:\t.get_fill_size\t=\ttcf_pedit_get_fill_size,\nnet/sched/act_pedit.c-662-\t.offload_act_setup =\ttcf_pedit_offload_act_setup,\n--\nnet/sched/act_police.c=442=static int tcf_police_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_police.c-492-\nnet/sched/act_police.c:493:static size_t tcf_police_get_fill_size(const struct tc_action *act)\nnet/sched/act_police.c-494-{\n--\nnet/sched/act_police.c=508=static struct tc_action_ops act_police_ops = {\n--\nnet/sched/act_police.c-516-\t.cleanup\t=\ttcf_police_cleanup,\nnet/sched/act_police.c:517:\t.get_fill_size\t=\ttcf_police_get_fill_size,\nnet/sched/act_police.c-518-\t.offload_act_setup =\ttcf_police_offload_act_setup,\n--\nnet/sched/act_sample.c=296=static int tcf_sample_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_sample.c-317-\nnet/sched/act_sample.c:318:static size_t tcf_sample_get_fill_size(const struct tc_action *act)\nnet/sched/act_sample.c-319-{\n--\nnet/sched/act_sample.c=326=static struct tc_action_ops act_sample_ops = {\n--\nnet/sched/act_sample.c-334-\t.cleanup = tcf_sample_cleanup,\nnet/sched/act_sample.c:335:\t.get_fill_size = tcf_sample_get_fill_size,\nnet/sched/act_sample.c-336-\t.get_psample_group = tcf_sample_get_group,\n--\nnet/sched/act_simple.c=61=static int reset_policy(struct tc_action *a, const struct nlattr *defdata,\n--\nnet/sched/act_simple.c-81-\nnet/sched/act_simple.c:82:static size_t tcf_simp_get_fill_size(const struct tc_action *act)\nnet/sched/act_simple.c-83-{\n--\nnet/sched/act_simple.c=207=static struct tc_action_ops act_simp_ops = {\n--\nnet/sched/act_simple.c-212-\t.dump\t\t=\ttcf_simp_dump,\nnet/sched/act_simple.c:213:\t.get_fill_size\t=\ttcf_simp_get_fill_size,\nnet/sched/act_simple.c-214-\t.cleanup\t=\ttcf_simp_release,\n--\nnet/sched/act_skbedit.c=348=static void tcf_skbedit_cleanup(struct tc_action *a)\n--\nnet/sched/act_skbedit.c-357-\nnet/sched/act_skbedit.c:358:static size_t tcf_skbedit_get_fill_size(const struct tc_action *act)\nnet/sched/act_skbedit.c-359-{\n--\nnet/sched/act_skbedit.c=418=static struct tc_action_ops act_skbedit_ops = {\n--\nnet/sched/act_skbedit.c-426-\t.cleanup\t=\ttcf_skbedit_cleanup,\nnet/sched/act_skbedit.c:427:\t.get_fill_size\t=\ttcf_skbedit_get_fill_size,\nnet/sched/act_skbedit.c-428-\t.offload_act_setup =\ttcf_skbedit_offload_act_setup,\n--\nnet/sched/act_skbmod.c=241=static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,\n--\nnet/sched/act_skbmod.c-281-\nnet/sched/act_skbmod.c:282:static size_t tcf_skbmod_get_fill_size(const struct tc_action *act)\nnet/sched/act_skbmod.c-283-{\n--\nnet/sched/act_skbmod.c=290=static struct tc_action_ops act_skbmod_ops = {\n--\nnet/sched/act_skbmod.c-295-\t.dump\t\t=\ttcf_skbmod_dump,\nnet/sched/act_skbmod.c:296:\t.get_fill_size\t=\ttcf_skbmod_get_fill_size,\nnet/sched/act_skbmod.c-297-\t.init\t\t=\ttcf_skbmod_init,\n--\nnet/sched/act_tunnel_key.c=860=static size_t tunnel_key_opts_fill_size(const struct ip_tunnel_info *info)\n--\nnet/sched/act_tunnel_key.c-885-\nnet/sched/act_tunnel_key.c:886:static size_t tunnel_key_get_fill_size(const struct tc_action *act)\nnet/sched/act_tunnel_key.c-887-{\n--\nnet/sched/act_tunnel_key.c=917=static struct tc_action_ops act_tunnel_key_ops = {\n--\nnet/sched/act_tunnel_key.c-924-\t.cleanup\t=\ttunnel_key_release,\nnet/sched/act_tunnel_key.c:925:\t.get_fill_size\t=\ttunnel_key_get_fill_size,\nnet/sched/act_tunnel_key.c-926-\t.offload_act_setup =\ttcf_tunnel_key_offload_act_setup,\n--\nnet/sched/act_vlan.c=336=static void tcf_vlan_stats_update(struct tc_action *a, u64 bytes, u64 packets,\n--\nnet/sched/act_vlan.c-345-\nnet/sched/act_vlan.c:346:static size_t tcf_vlan_get_fill_size(const struct tc_action *act)\nnet/sched/act_vlan.c-347-{\n--\nnet/sched/act_vlan.c=416=static struct tc_action_ops act_vlan_ops = {\n--\nnet/sched/act_vlan.c-424-\t.stats_update\t=\ttcf_vlan_stats_update,\nnet/sched/act_vlan.c:425:\t.get_fill_size\t=\ttcf_vlan_get_fill_size,\nnet/sched/act_vlan.c-426-\t.offload_act_setup =\ttcf_vlan_offload_act_setup,\n"
} |
| 45/2 | 2026/09/22 05:25 | llm | patch-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 33640 output: 330 thoughts: 1566 Thoughts: **Analysis of TC Action Updates for Fuzzing** Okay, so this is about the addition and correction of `.get_fill_size` for various traffic control (TC) actions. The patch meticulously addresses missing implementations (`act_connmark`, `act_mpls`, `act_nat`, `act_simple`, `act_skbmod`), corrects an issue with `act_mirred` by including `TCA_MIRRED_BLOCKID`, and crucially, integrates `tcf_action_warn_attr_size(extack)` into `tcf_del_notify_msg` and `tcf_add_notify_msg` within `net/sched/act_api.c`. This is all crystal clear. Now, let's nail down the `FocusSymbols`. The modified functions or the ones directly involved are: `tcf_action_warn_attr_size`, `tcf_del_notify_msg`, `tcf_add_notify_msg` (all in `act_api.c`), the `*_get_fill_size` functions for `act_connmark`, `act_mirred`, `act_mpls`, `act_nat`, `act_simple`, and `act_skbmod`. We also need to include `tcf_del_notify` and `tcf_add_notify`, since they call the `*_notify_msg` variants. These choices are specific, they aren't ubiquitous and directly address the introduced changes. `tc_ctl_action` is relevant to TC, but potentially too broad, and doesn't directly capture the code being changed. This is a good, targeted list. The next step is to nail down the `EnableConfigs`. We'll need `NET_CLS_ACT` for the core `net/sched/act_api.c` modifications. Then, for the specific actions, we'll need `NET_ACT_CONNMARK` (dependent on `NET_CLS_ACT`, `NETFILTER`, and `NF_CONNTRACK` with its `NF_CONNTRACK_MARK` dependency), `NET_ACT_MIRRED`, `NET_ACT_MPLS`, `NET_ACT_NAT`, `NET_ACT_SIMP`, and `NET_ACT_SKBMOD` (all dependent on `NET_CLS_ACT`). Digging through the Kconfig files, this seems sound. We are certain that `NET_CLS_ACT`, `NET_ACT_CONNMARK`, `NET_ACT_MIRRED`, `NET_ACT_MPLS`, `NET_ACT_NAT`, `NET_ACT_SIMP`, `NET_ACT_SKBMOD`, `NF_CONNTRACK`, and `NF_CONNTRACK_MARK` are all necessary to compile and reach every modified file and function. Finally, we have to prepare the `set-results`. Based on our review, `EnableConfigs` will be a list of configuration options without the `CONFIG_` prefix. Our `FocusSymbols` are listed above. I believe the reasoning is clear and concise - this patch modifies core TC action notification messages and adds crucial size calculation functions for new and existing actions. The functions are directly related to the patch, not ubiquitous, and can be fuzzed directly. And, yes, this is absolutely `WorthFuzzing`. The listed functions are directly touched by the patch and the dependencies are properly configured. |
| 46/2 | 2026/09/22 05:25 | tool | set-results |
0mArgs:{
"EnableConfigs": [
"NET_CLS_ACT",
"NET_ACT_CONNMARK",
"NET_ACT_MIRRED",
"NET_ACT_MPLS",
"NET_ACT_NAT",
"NET_ACT_SIMP",
"NET_ACT_SKBMOD",
"NF_CONNTRACK",
"NF_CONNTRACK_MARK"
],
"FocusSymbols": [
"tcf_add_notify_msg",
"tcf_del_notify_msg",
"tcf_connmark_get_fill_size",
"tcf_mirred_get_fill_size",
"tcf_mpls_get_fill_size",
"tcf_nat_get_fill_size",
"tcf_simp_get_fill_size",
"tcf_skbmod_get_fill_size"
],
"Reasoning": "The patch modifies buffer size calculations for netlink TC action notification messages (accounting for extack warning messages) in net/sched/act_api.c and adds/updates .get_fill_size callbacks across multiple traffic control actions (connmark, mirred, mpls, nat, simple, skbmod). These changes affect skb allocation sizing during netlink action operations (RTM_NEWACTION, RTM_DELACTION), which are reachable from userspace via rtnetlink and warrant fuzzing to catch potential buffer miscalculations, memory corruption, or message formatting errors.",
"WorthFuzzing": true
}Results: {
"EnableConfigs": [
"NET_CLS_ACT",
"NET_ACT_CONNMARK",
"NET_ACT_MIRRED",
"NET_ACT_MPLS",
"NET_ACT_NAT",
"NET_ACT_SIMP",
"NET_ACT_SKBMOD",
"NF_CONNTRACK",
"NF_CONNTRACK_MARK"
],
"FocusSymbols": [
"tcf_add_notify_msg",
"tcf_del_notify_msg",
"tcf_connmark_get_fill_size",
"tcf_mirred_get_fill_size",
"tcf_mpls_get_fill_size",
"tcf_nat_get_fill_size",
"tcf_simp_get_fill_size",
"tcf_skbmod_get_fill_size"
],
"Reasoning": "The patch modifies buffer size calculations for netlink TC action notification messages (accounting for extack warning messages) in net/sched/act_api.c and adds/updates .get_fill_size callbacks across multiple traffic control actions (connmark, mirred, mpls, nat, simple, skbmod). These changes affect skb allocation sizing during netlink action operations (RTM_NEWACTION, RTM_DELACTION), which are reachable from userspace via rtnetlink and warrant fuzzing to catch potential buffer miscalculations, memory corruption, or message formatting errors.",
"WorthFuzzing": true
} |
| 47/1 | 2026/09/22 05:25 | action | If |
1mArgs:{
"WorthFuzzing": true
}Results: null |
| 48/2 | 2026/09/22 05:25 | agent | kmsan-evaluator |
1mModel:core Args: null Results: {
"KMSANReasoning": "The patch series improves the buffer allocation size calculations for netlink notification skbs in the TC action subsystem (net/sched). Specifically, it accounts for potential warning messages from netlink_ext_ack in tcf_action_warn_attr_size() when allocating skbs in tcf_del_notify_msg() and tcf_add_notify_msg(), and implements/corrects the .get_fill_size callback for several action modules (act_connmark, act_mirred, act_mpls, act_nat, act_simple, act_skbmod) so that the maximum size needed by their dump callbacks is pre-calculated accurately.\n\nThese changes only affect the size argument passed to alloc_skb() to prevent buffer exhaustion and message trimming during tca_get_fill(). They do not introduce, modify, or expose any uninitialized memory or info-leaks:\n1. No changes are made to how data is serialized or dumped into netlink skbs; the dump functions themselves are unchanged and already properly initialize all structs before calling nla_put().\n2. The skb buffer sizing does not affect the amount of data copied to userspace, as skb-\u003elen is determined strictly by the formatted netlink attributes.\n3. No uninitialized variables, heap allocations, or struct fields are read or branched upon.\n\nBecause there are no uninitialized memory risks or kernel-to-user info-leak risks, running a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
}Instruction: You are an expert Linux kernel security engineer specializing in kernel memory
error detectors (KASAN and KMSAN). Your job is to review the provided patch series and
determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer)
fuzzing session in addition to standard KASAN fuzzing.
CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN:
- Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable
a comprehensive suite of debugging tools and sanitizers, including KASAN
(out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP
(locking bugs and deadlocks), UB-sanitizers, and memory corruption checks.
- KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap,
or page allocations) and kernel-to-user memory info-leaks.
Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN,
LOCKDEP, OR OTHER STANDARD BUG DETECTORS.
A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY
set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks
that are detected ONLY by KMSAN.
Look holistically at the patch series and surrounding code. Even if no direct
uninitialized field accesses or new buffer allocations are added in the diff itself,
a patch may alter control flow, bounds checking, or data length calculations in ways
that change how the rest of the code operates on existing buffers (e.g. allowing
uninitialized stack/heap memory to be read, copied to user space, or used in control
flow). Do not hesitate to use your code access tools to inspect the surrounding code,
called functions, and callers.
Set NeedsKMSAN=true ONLY IF the patch introduces or modifies:
1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb
attributes, ioctl output arguments, socket options, or BPF buffers) where fields
or structure padding might not be fully initialized/zeroed.
2. Conditional logic or branching that depends on potentially uninitialized variables
or struct fields.
3. Allocation or initialization of complex data structures where uninitialized fields
could be read later in reachable code paths.
4. Bounds checks, lengths, or logic in a way that allows surrounding code to access
uninitialized bytes of existing buffers.
Set NeedsKMSAN=false IF:
- The code changes primarily risk out-of-bounds access, array overflows, NULL pointer
dereferences, locking deadlocks, or use-after-free bugs (these are already caught
by KASAN, LOCKDEP, or standard bug detectors).
- All stack/heap structures touched or introduced by the patch are fully zeroed
or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied.
- The patch does not introduce any risk of uninitialized memory usage or info-leaks.
Use your code access tools to inspect the surrounding code if necessary, then provide
detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch.
Prefer calling several tools at the same time to save round-trips.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt: Target architecture: amd64
For your convenience, here is the diff of the changes:
commit 5d4c87dd0e20cf5216e924576264f1cef012ba5e
Author: syz-cluster <triage@syzkaller.com>
Date: Tue Sep 22 05:23:24 2026 +0000
syz-cluster: applied patch under review
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 3f653721c45fe..db06ddcf6ae67 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -475,6 +475,15 @@ static size_t tcf_action_full_attrs_size(size_t sz)
+ sz;
}
+/* tca_get_fill() may append TCA_ROOT_EXT_WARN_MSG from extack->_msg */
+static size_t tcf_action_warn_attr_size(const struct netlink_ext_ack *extack)
+{
+ if (unlikely(extack && extack->_msg))
+ return nla_total_size(strlen(extack->_msg) + 1);
+
+ return 0;
+}
+
static size_t tcf_action_fill_size(const struct tc_action *act)
{
size_t sz = tcf_action_shared_attrs_size(act);
@@ -1980,7 +1989,8 @@ static struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,
{
struct sk_buff *skb;
- skb = alloc_skb(max(attr_size, NLMSG_GOODSIZE), GFP_KERNEL);
+ skb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),
+ NLMSG_GOODSIZE), GFP_KERNEL);
if (!skb)
return ERR_PTR(-ENOBUFS);
@@ -2078,7 +2088,8 @@ static struct sk_buff *tcf_add_notify_msg(struct net *net, struct nlmsghdr *n,
{
struct sk_buff *skb;
- skb = alloc_skb(max(attr_size, NLMSG_GOODSIZE), GFP_KERNEL);
+ skb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),
+ NLMSG_GOODSIZE), GFP_KERNEL);
if (!skb)
return ERR_PTR(-ENOBUFS);
diff --git a/net/sched/act_connmark.c b/net/sched/act_connmark.c
index c634af5edfcdc..0b6ac6be60d24 100644
--- a/net/sched/act_connmark.c
+++ b/net/sched/act_connmark.c
@@ -236,12 +236,18 @@ static void tcf_connmark_cleanup(struct tc_action *a)
kfree_rcu(parms, rcu);
}
+static size_t tcf_connmark_get_fill_size(const struct tc_action *act)
+{
+ return nla_total_size(sizeof(struct tc_connmark)); /* TCA_CONNMARK_PARMS */
+}
+
static struct tc_action_ops act_connmark_ops = {
.kind = "connmark",
.id = TCA_ID_CONNMARK,
.owner = THIS_MODULE,
.act = tcf_connmark_act,
.dump = tcf_connmark_dump,
+ .get_fill_size = tcf_connmark_get_fill_size,
.init = tcf_connmark_init,
.cleanup = tcf_connmark_cleanup,
.size = sizeof(struct tcf_connmark_info),
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 553342c55cf7c..1c98e4d81ebe6 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -607,7 +607,8 @@ tcf_mirred_get_dev(const struct tc_action *a,
static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
{
- return nla_total_size(sizeof(struct tc_mirred));
+ return nla_total_size(sizeof(struct tc_mirred)) /* TCA_MIRRED_PARMS */
+ + nla_total_size(sizeof(u32)); /* TCA_MIRRED_BLOCKID */
}
static void tcf_offload_mirred_get_dev(struct flow_action_entry *entry,
diff --git a/net/sched/act_mpls.c b/net/sched/act_mpls.c
index 4ea8b2e08c3a4..aa56521b71798 100644
--- a/net/sched/act_mpls.c
+++ b/net/sched/act_mpls.c
@@ -438,12 +438,23 @@ static int tcf_mpls_offload_act_setup(struct tc_action *act, void *entry_data,
return 0;
}
+static size_t tcf_mpls_get_fill_size(const struct tc_action *act)
+{
+ return nla_total_size(sizeof(struct tc_mpls)) /* TCA_MPLS_PARMS */
+ + nla_total_size(sizeof(u32)) /* TCA_MPLS_LABEL */
+ + nla_total_size(sizeof(u8)) /* TCA_MPLS_TC */
+ + nla_total_size(sizeof(u8)) /* TCA_MPLS_TTL */
+ + nla_total_size(sizeof(u8)) /* TCA_MPLS_BOS */
+ + nla_total_size(sizeof(u16)); /* TCA_MPLS_PROTO */
+}
+
static struct tc_action_ops act_mpls_ops = {
.kind = "mpls",
.id = TCA_ID_MPLS,
.owner = THIS_MODULE,
.act = tcf_mpls_act,
.dump = tcf_mpls_dump,
+ .get_fill_size = tcf_mpls_get_fill_size,
.init = tcf_mpls_init,
.cleanup = tcf_mpls_cleanup,
.offload_act_setup = tcf_mpls_offload_act_setup,
diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index abb332dee836d..a201979ac7cf7 100644
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -313,12 +313,18 @@ static void tcf_nat_cleanup(struct tc_action *a)
kfree_rcu(parms, rcu);
}
+static size_t tcf_nat_get_fill_size(const struct tc_action *act)
+{
+ return nla_total_size(sizeof(struct tc_nat)); /* TCA_NAT_PARMS */
+}
+
static struct tc_action_ops act_nat_ops = {
.kind = "nat",
.id = TCA_ID_NAT,
.owner = THIS_MODULE,
.act = tcf_nat_act,
.dump = tcf_nat_dump,
+ .get_fill_size = tcf_nat_get_fill_size,
.init = tcf_nat_init,
.cleanup = tcf_nat_cleanup,
.size = sizeof(struct tcf_nat),
diff --git a/net/sched/act_simple.c b/net/sched/act_simple.c
index 8e69a919b4fee..80e5084b4dbd7 100644
--- a/net/sched/act_simple.c
+++ b/net/sched/act_simple.c
@@ -79,6 +79,12 @@ static int reset_policy(struct tc_action *a, const struct nlattr *defdata,
return 0;
}
+static size_t tcf_simp_get_fill_size(const struct tc_action *act)
+{
+ return nla_total_size(sizeof(struct tc_defact)) /* TCA_DEF_PARMS */
+ + nla_total_size(SIMP_MAX_DATA); /* TCA_DEF_DATA */
+}
+
static const struct nla_policy simple_policy[TCA_DEF_MAX + 1] = {
[TCA_DEF_PARMS] = { .len = sizeof(struct tc_defact) },
[TCA_DEF_DATA] = { .type = NLA_STRING, .len = SIMP_MAX_DATA },
@@ -204,6 +210,7 @@ static struct tc_action_ops act_simp_ops = {
.owner = THIS_MODULE,
.act = tcf_simp_act,
.dump = tcf_simp_dump,
+ .get_fill_size = tcf_simp_get_fill_size,
.cleanup = tcf_simp_release,
.init = tcf_simp_init,
.size = sizeof(struct tcf_defact),
diff --git a/net/sched/act_skbmod.c b/net/sched/act_skbmod.c
index 7579cf1e0ff37..09e9dcf582531 100644
--- a/net/sched/act_skbmod.c
+++ b/net/sched/act_skbmod.c
@@ -279,12 +279,21 @@ static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,
return -1;
}
+static size_t tcf_skbmod_get_fill_size(const struct tc_action *act)
+{
+ return nla_total_size(sizeof(struct tc_skbmod)) /* TCA_SKBMOD_PARMS */
+ + nla_total_size(ETH_ALEN) /* TCA_SKBMOD_DMAC */
+ + nla_total_size(ETH_ALEN) /* TCA_SKBMOD_SMAC */
+ + nla_total_size(sizeof(u16)); /* TCA_SKBMOD_ETYPE */
+}
+
static struct tc_action_ops act_skbmod_ops = {
.kind = "skbmod",
.id = TCA_ACT_SKBMOD,
.owner = THIS_MODULE,
.act = tcf_skbmod_act,
.dump = tcf_skbmod_dump,
+ .get_fill_size = tcf_skbmod_get_fill_size,
.init = tcf_skbmod_init,
.cleanup = tcf_skbmod_cleanup,
.size = sizeof(struct tcf_skbmod),
|
| 49/3 | 2026/09/22 05:25 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 4806 output: 29 thoughts: 409 Thoughts: **My Assessment of the Patch** Okay, so this patch is touching a number of action modules within the networking scheduler (`net/sched/`). It looks like the core modification revolves around how the size of Netlink messages are calculated and allocated, specifically concerning the error reporting. I see it's changing the allocation size in `net/sched/act_api.c`. It's increasing the allocation in `tcf_del_notify_msg` and `tcf_add_notify_msg` to include space for an extended acknowledgement (`extack`) message, and that's based on `tcf_action_warn_attr_size(extack)`. Previously, it appears the allocation was only based on the `attr_size` and a minimum size (`NLMSG_GOODSIZE`), but now we're incorporating space for these warning messages. The other thing that stands out is the inclusion or expansion of `get_fill_size` across several action modules like `act_connmark.c`, `act_mirred.c`, `act_mpls.c`, `act_nat.c`, `act_simple.c`, and `act_skbmod.c`. This suggests a unified approach to calculate and potentially optimize message sizes on a per-action basis. So it's likely the patch is trying to ensure we have enough space for the action-specific attributes, plus the error reporting, within the Netlink messages. To understand the implications fully, I need to dig deeper into how `get_fill_size` and `attr_size` are actually used within `act_api.c`. I'm going to run a `read-file` or `grepper` command to quickly scan the surrounding code in that file and see how the size calculations are used and what they influence. This will help me understand the purpose of the patch. |
| 50/3 | 2026/09/22 05:25 | tool | grepper |
0mArgs:{
"Expression": "get_fill_size",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=487=static size_t tcf_action_fill_size(const struct tc_action *act)\n--\nnet/sched/act_api.c-490-\nnet/sched/act_api.c:491:\tif (act-\u003eops-\u003eget_fill_size)\nnet/sched/act_api.c:492:\t\treturn act-\u003eops-\u003eget_fill_size(act) + sz;\nnet/sched/act_api.c-493-\treturn sz;\n--\nnet/sched/act_bpf.c=384=static void tcf_bpf_cleanup(struct tc_action *act)\n--\nnet/sched/act_bpf.c-391-\nnet/sched/act_bpf.c:392:static size_t tcf_bpf_get_fill_size(const struct tc_action *act)\nnet/sched/act_bpf.c-393-{\n--\nnet/sched/act_bpf.c=417=static struct tc_action_ops act_bpf_ops __read_mostly = {\n--\nnet/sched/act_bpf.c-424-\t.init\t\t=\ttcf_bpf_init,\nnet/sched/act_bpf.c:425:\t.get_fill_size\t=\ttcf_bpf_get_fill_size,\nnet/sched/act_bpf.c-426-\t.size\t\t=\tsizeof(struct tcf_bpf),\n--\nnet/sched/act_connmark.c=229=static void tcf_connmark_cleanup(struct tc_action *a)\n--\nnet/sched/act_connmark.c-238-\nnet/sched/act_connmark.c:239:static size_t tcf_connmark_get_fill_size(const struct tc_action *act)\nnet/sched/act_connmark.c-240-{\n--\nnet/sched/act_connmark.c=244=static struct tc_action_ops act_connmark_ops = {\n--\nnet/sched/act_connmark.c-249-\t.dump\t\t=\ttcf_connmark_dump,\nnet/sched/act_connmark.c:250:\t.get_fill_size\t=\ttcf_connmark_get_fill_size,\nnet/sched/act_connmark.c-251-\t.init\t\t=\ttcf_connmark_init,\n--\nnet/sched/act_csum.c=674=static void tcf_csum_cleanup(struct tc_action *a)\n--\nnet/sched/act_csum.c-683-\nnet/sched/act_csum.c:684:static size_t tcf_csum_get_fill_size(const struct tc_action *act)\nnet/sched/act_csum.c-685-{\n--\nnet/sched/act_csum.c=708=static struct tc_action_ops act_csum_ops = {\n--\nnet/sched/act_csum.c-715-\t.cleanup\t= tcf_csum_cleanup,\nnet/sched/act_csum.c:716:\t.get_fill_size = tcf_csum_get_fill_size,\nnet/sched/act_csum.c-717-\t.offload_act_setup = tcf_csum_offload_act_setup,\n--\nnet/sched/act_ct.c=1636=static int tcf_ct_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_ct.c-1659-\nnet/sched/act_ct.c:1660:static size_t tcf_ct_get_fill_size(const struct tc_action *act)\nnet/sched/act_ct.c-1661-{\n--\nnet/sched/act_ct.c=1705=static struct tc_action_ops act_ct_ops = {\n--\nnet/sched/act_ct.c-1713-\t.stats_update\t=\ttcf_stats_update,\nnet/sched/act_ct.c:1714:\t.get_fill_size\t=\ttcf_ct_get_fill_size,\nnet/sched/act_ct.c-1715-\t.offload_act_setup =\ttcf_ct_offload_act_setup,\n--\nnet/sched/act_ctinfo.c=349=static void tcf_ctinfo_cleanup(struct tc_action *a)\n--\nnet/sched/act_ctinfo.c-358-\nnet/sched/act_ctinfo.c:359:static size_t tcf_ctinfo_get_fill_size(const struct tc_action *act)\nnet/sched/act_ctinfo.c-360-{\n--\nnet/sched/act_ctinfo.c=369=static struct tc_action_ops act_ctinfo_ops = {\n--\nnet/sched/act_ctinfo.c-376-\t.cleanup= tcf_ctinfo_cleanup,\nnet/sched/act_ctinfo.c:377:\t.get_fill_size = tcf_ctinfo_get_fill_size,\nnet/sched/act_ctinfo.c-378-\t.size\t= sizeof(struct tcf_ctinfo),\n--\nnet/sched/act_gact.c=190=static int tcf_gact_dump(struct sk_buff *skb, struct tc_action *a,\n--\nnet/sched/act_gact.c-230-\nnet/sched/act_gact.c:231:static size_t tcf_gact_get_fill_size(const struct tc_action *act)\nnet/sched/act_gact.c-232-{\n--\nnet/sched/act_gact.c=292=static struct tc_action_ops act_gact_ops = {\n--\nnet/sched/act_gact.c-299-\t.init\t\t=\ttcf_gact_init,\nnet/sched/act_gact.c:300:\t.get_fill_size\t=\ttcf_gact_get_fill_size,\nnet/sched/act_gact.c-301-\t.offload_act_setup =\ttcf_gact_offload_act_setup,\n--\nnet/sched/act_gate.c=672=static void tcf_gate_stats_update(struct tc_action *a, u64 bytes, u64 packets,\n--\nnet/sched/act_gate.c-681-\nnet/sched/act_gate.c:682:static size_t tcf_gate_get_fill_size(const struct tc_action *act)\nnet/sched/act_gate.c-683-{\n--\nnet/sched/act_gate.c=736=static struct tc_action_ops act_gate_ops = {\n--\nnet/sched/act_gate.c-744-\t.stats_update\t=\ttcf_gate_stats_update,\nnet/sched/act_gate.c:745:\t.get_fill_size\t=\ttcf_gate_get_fill_size,\nnet/sched/act_gate.c-746-\t.offload_act_setup =\ttcf_gate_offload_act_setup,\n--\nnet/sched/act_ife.c=881=TC_INDIRECT_SCOPE int tcf_ife_act(struct sk_buff *skb,\n--\nnet/sched/act_ife.c-904-\nnet/sched/act_ife.c:905:static size_t tcf_ife_get_fill_size(const struct tc_action *act)\nnet/sched/act_ife.c-906-{\n--\nnet/sched/act_ife.c=927=static struct tc_action_ops act_ife_ops = {\n--\nnet/sched/act_ife.c-934-\t.init = tcf_ife_init,\nnet/sched/act_ife.c:935:\t.get_fill_size = tcf_ife_get_fill_size,\nnet/sched/act_ife.c-936-\t.size =\tsizeof(struct tcf_ife_info),\n--\nnet/sched/act_mirred.c=591=tcf_mirred_get_dev(const struct tc_action *a,\n--\nnet/sched/act_mirred.c-607-\nnet/sched/act_mirred.c:608:static size_t tcf_mirred_get_fill_size(const struct tc_action *act)\nnet/sched/act_mirred.c-609-{\n--\nnet/sched/act_mirred.c=665=static struct tc_action_ops act_mirred_ops = {\n--\nnet/sched/act_mirred.c-673-\t.init\t\t=\ttcf_mirred_init,\nnet/sched/act_mirred.c:674:\t.get_fill_size\t=\ttcf_mirred_get_fill_size,\nnet/sched/act_mirred.c-675-\t.offload_act_setup =\ttcf_mirred_offload_act_setup,\n--\nnet/sched/act_mpls.c=382=static int tcf_mpls_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_mpls.c-440-\nnet/sched/act_mpls.c:441:static size_t tcf_mpls_get_fill_size(const struct tc_action *act)\nnet/sched/act_mpls.c-442-{\n--\nnet/sched/act_mpls.c=451=static struct tc_action_ops act_mpls_ops = {\n--\nnet/sched/act_mpls.c-456-\t.dump\t\t=\ttcf_mpls_dump,\nnet/sched/act_mpls.c:457:\t.get_fill_size\t=\ttcf_mpls_get_fill_size,\nnet/sched/act_mpls.c-458-\t.init\t\t=\ttcf_mpls_init,\n--\nnet/sched/act_nat.c=306=static void tcf_nat_cleanup(struct tc_action *a)\n--\nnet/sched/act_nat.c-315-\nnet/sched/act_nat.c:316:static size_t tcf_nat_get_fill_size(const struct tc_action *act)\nnet/sched/act_nat.c-317-{\n--\nnet/sched/act_nat.c=321=static struct tc_action_ops act_nat_ops = {\n--\nnet/sched/act_nat.c-326-\t.dump\t\t=\ttcf_nat_dump,\nnet/sched/act_nat.c:327:\t.get_fill_size\t=\ttcf_nat_get_fill_size,\nnet/sched/act_nat.c-328-\t.init\t\t=\ttcf_nat_init,\n--\nnet/sched/act_pedit.c=564=static int tcf_pedit_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_pedit.c-628-\nnet/sched/act_pedit.c:629:static size_t tcf_pedit_get_fill_size(const struct tc_action *act)\nnet/sched/act_pedit.c-630-{\n--\nnet/sched/act_pedit.c=652=static struct tc_action_ops act_pedit_ops = {\n--\nnet/sched/act_pedit.c-660-\t.init\t\t=\ttcf_pedit_init,\nnet/sched/act_pedit.c:661:\t.get_fill_size\t=\ttcf_pedit_get_fill_size,\nnet/sched/act_pedit.c-662-\t.offload_act_setup =\ttcf_pedit_offload_act_setup,\n--\nnet/sched/act_police.c=442=static int tcf_police_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_police.c-492-\nnet/sched/act_police.c:493:static size_t tcf_police_get_fill_size(const struct tc_action *act)\nnet/sched/act_police.c-494-{\n--\nnet/sched/act_police.c=508=static struct tc_action_ops act_police_ops = {\n--\nnet/sched/act_police.c-516-\t.cleanup\t=\ttcf_police_cleanup,\nnet/sched/act_police.c:517:\t.get_fill_size\t=\ttcf_police_get_fill_size,\nnet/sched/act_police.c-518-\t.offload_act_setup =\ttcf_police_offload_act_setup,\n--\nnet/sched/act_sample.c=296=static int tcf_sample_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_sample.c-317-\nnet/sched/act_sample.c:318:static size_t tcf_sample_get_fill_size(const struct tc_action *act)\nnet/sched/act_sample.c-319-{\n--\nnet/sched/act_sample.c=326=static struct tc_action_ops act_sample_ops = {\n--\nnet/sched/act_sample.c-334-\t.cleanup = tcf_sample_cleanup,\nnet/sched/act_sample.c:335:\t.get_fill_size = tcf_sample_get_fill_size,\nnet/sched/act_sample.c-336-\t.get_psample_group = tcf_sample_get_group,\n--\nnet/sched/act_simple.c=61=static int reset_policy(struct tc_action *a, const struct nlattr *defdata,\n--\nnet/sched/act_simple.c-81-\nnet/sched/act_simple.c:82:static size_t tcf_simp_get_fill_size(const struct tc_action *act)\nnet/sched/act_simple.c-83-{\n--\nnet/sched/act_simple.c=207=static struct tc_action_ops act_simp_ops = {\n--\nnet/sched/act_simple.c-212-\t.dump\t\t=\ttcf_simp_dump,\nnet/sched/act_simple.c:213:\t.get_fill_size\t=\ttcf_simp_get_fill_size,\nnet/sched/act_simple.c-214-\t.cleanup\t=\ttcf_simp_release,\n--\nnet/sched/act_skbedit.c=348=static void tcf_skbedit_cleanup(struct tc_action *a)\n--\nnet/sched/act_skbedit.c-357-\nnet/sched/act_skbedit.c:358:static size_t tcf_skbedit_get_fill_size(const struct tc_action *act)\nnet/sched/act_skbedit.c-359-{\n--\nnet/sched/act_skbedit.c=418=static struct tc_action_ops act_skbedit_ops = {\n--\nnet/sched/act_skbedit.c-426-\t.cleanup\t=\ttcf_skbedit_cleanup,\nnet/sched/act_skbedit.c:427:\t.get_fill_size\t=\ttcf_skbedit_get_fill_size,\nnet/sched/act_skbedit.c-428-\t.offload_act_setup =\ttcf_skbedit_offload_act_setup,\n--\nnet/sched/act_skbmod.c=241=static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,\n--\nnet/sched/act_skbmod.c-281-\nnet/sched/act_skbmod.c:282:static size_t tcf_skbmod_get_fill_size(const struct tc_action *act)\nnet/sched/act_skbmod.c-283-{\n--\nnet/sched/act_skbmod.c=290=static struct tc_action_ops act_skbmod_ops = {\n--\nnet/sched/act_skbmod.c-295-\t.dump\t\t=\ttcf_skbmod_dump,\nnet/sched/act_skbmod.c:296:\t.get_fill_size\t=\ttcf_skbmod_get_fill_size,\nnet/sched/act_skbmod.c-297-\t.init\t\t=\ttcf_skbmod_init,\n--\nnet/sched/act_tunnel_key.c=860=static size_t tunnel_key_opts_fill_size(const struct ip_tunnel_info *info)\n--\nnet/sched/act_tunnel_key.c-885-\nnet/sched/act_tunnel_key.c:886:static size_t tunnel_key_get_fill_size(const struct tc_action *act)\nnet/sched/act_tunnel_key.c-887-{\n--\nnet/sched/act_tunnel_key.c=917=static struct tc_action_ops act_tunnel_key_ops = {\n--\nnet/sched/act_tunnel_key.c-924-\t.cleanup\t=\ttunnel_key_release,\nnet/sched/act_tunnel_key.c:925:\t.get_fill_size\t=\ttunnel_key_get_fill_size,\nnet/sched/act_tunnel_key.c-926-\t.offload_act_setup =\ttcf_tunnel_key_offload_act_setup,\n--\nnet/sched/act_vlan.c=336=static void tcf_vlan_stats_update(struct tc_action *a, u64 bytes, u64 packets,\n--\nnet/sched/act_vlan.c-345-\nnet/sched/act_vlan.c:346:static size_t tcf_vlan_get_fill_size(const struct tc_action *act)\nnet/sched/act_vlan.c-347-{\n--\nnet/sched/act_vlan.c=416=static struct tc_action_ops act_vlan_ops = {\n--\nnet/sched/act_vlan.c-424-\t.stats_update\t=\ttcf_vlan_stats_update,\nnet/sched/act_vlan.c:425:\t.get_fill_size\t=\ttcf_vlan_get_fill_size,\nnet/sched/act_vlan.c-426-\t.offload_act_setup =\ttcf_vlan_offload_act_setup,\n"
} |
| 51/3 | 2026/09/22 05:25 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 10515 output: 37 thoughts: 36 Thoughts: Here's a summary of my thought process, as if I were analyzing that code: **Diving into `act_api.c`** Okay, so I need to get a handle on what's happening within `act_api.c`. Based on the file name, this is likely where the core API functionality for my "act" system resides. To really understand the flow, I want to zero in on a couple of specific sections. The line numbers are a good start. I want to examine lines 470-520 and 1970-2100. By doing so, I'll be able to compare related function flows to grasp the intent of the author. Based on the file name I'm guessing these are very important sections. I need to understand what's happening around these lines to grasp the flow. Let's see what the code has to offer! |
| 52/3 | 2026/09/22 05:26 | tool | read-file |
0mArgs:{
"File": "net/sched/act_api.c",
"FirstLine": 470,
"LineCount": 60
}Results: {
"Contents": " 470:\tstatic size_t tcf_action_full_attrs_size(size_t sz)\n 471:\t{\n 472:\t\treturn NLMSG_HDRLEN /* struct nlmsghdr */\n 473:\t\t\t+ sizeof(struct tcamsg)\n 474:\t\t\t+ nla_total_size(0) /* TCA_ACT_TAB nested */\n 475:\t\t\t+ sz;\n 476:\t}\n 477:\t\n 478:\t/* tca_get_fill() may append TCA_ROOT_EXT_WARN_MSG from extack-\u003e_msg */\n 479:\tstatic size_t tcf_action_warn_attr_size(const struct netlink_ext_ack *extack)\n 480:\t{\n 481:\t\tif (unlikely(extack \u0026\u0026 extack-\u003e_msg))\n 482:\t\t\treturn nla_total_size(strlen(extack-\u003e_msg) + 1);\n 483:\t\n 484:\t\treturn 0;\n 485:\t}\n 486:\t\n 487:\tstatic size_t tcf_action_fill_size(const struct tc_action *act)\n 488:\t{\n 489:\t\tsize_t sz = tcf_action_shared_attrs_size(act);\n 490:\t\n 491:\t\tif (act-\u003eops-\u003eget_fill_size)\n 492:\t\t\treturn act-\u003eops-\u003eget_fill_size(act) + sz;\n 493:\t\treturn sz;\n 494:\t}\n 495:\t\n 496:\tstatic int\n 497:\ttcf_action_dump_terse(struct sk_buff *skb, struct tc_action *a, bool from_act)\n 498:\t{\n 499:\t\tunsigned char *b = skb_tail_pointer(skb);\n 500:\t\tstruct tc_cookie *cookie;\n 501:\t\n 502:\t\tif (nla_put_string(skb, TCA_ACT_KIND, a-\u003eops-\u003ekind))\n 503:\t\t\tgoto nla_put_failure;\n 504:\t\tif (tcf_action_copy_stats(skb, a, 0))\n 505:\t\t\tgoto nla_put_failure;\n 506:\t\tif (from_act \u0026\u0026 nla_put_u32(skb, TCA_ACT_INDEX, a-\u003etcfa_index))\n 507:\t\t\tgoto nla_put_failure;\n 508:\t\n 509:\t\trcu_read_lock();\n 510:\t\tcookie = rcu_dereference(a-\u003euser_cookie);\n 511:\t\tif (cookie) {\n 512:\t\t\tif (nla_put(skb, TCA_ACT_COOKIE, cookie-\u003elen, cookie-\u003edata)) {\n 513:\t\t\t\trcu_read_unlock();\n 514:\t\t\t\tgoto nla_put_failure;\n 515:\t\t\t}\n 516:\t\t}\n 517:\t\trcu_read_unlock();\n 518:\t\n 519:\t\treturn 0;\n 520:\t\n 521:\tnla_put_failure:\n 522:\t\tnlmsg_trim(skb, b);\n 523:\t\treturn -1;\n 524:\t}\n 525:\t\n 526:\tstatic int\n 527:\ttcf_action_dump_1(struct sk_buff *skb, struct tc_action *a, int bind, int ref)\n 528:\t{\n 529:\t\tunsigned char *b = skb_tail_pointer(skb);\n"
} |
| 53/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 11744 output: 38 thoughts: 27 Thoughts: Here's my summary, as though I'm thinking through this process: **Diving into the `act_api.c` Code** Okay, time to get my hands dirty. Let's start by zeroing in on a specific section of the kernel: lines 1970 through 2100 in `net/sched/act_api.c`. This is where I expect to find the core logic related to... *[I'd insert the relevant component from your field here; e.g., "traffic shaping action configurations," "the interaction between action modules and the scheduler," etc.]*. I need to understand how *[specific problem from your field]* works or to trace *[a particular function call from your field]* to find *[specific results from your field]*. This section is probably where the key data structures and function calls related to *[relevant concepts from your field]* are defined and implemented. I'm hoping to quickly identify the points of interest within this block, perhaps looking for key function calls like `act_register` and `act_destroy`, or data structures that store the configuration parameters. I’ll start by a quick scan for the main functions, then go through the code line by line and start thinking about the implications. |
| 54/3 | 2026/09/22 05:26 | tool | read-file |
0mArgs:{
"File": "net/sched/act_api.c",
"FirstLine": 1970,
"LineCount": 80
}Results: {
"Contents": "1970:\t\t\t\t\tif (ret \u003c 0)\n1971:\t\t\t\t\t\tcontinue;\n1972:\t\t\t\t\tif (tc_act_skip_sw(p-\u003etcfa_flags) \u0026\u0026\n1973:\t\t\t\t\t !tc_act_in_hw(p))\n1974:\t\t\t\t\t\ttcf_reoffload_del_notify(net, p);\n1975:\t\t\t\t}\n1976:\t\t\t\tmutex_unlock(\u0026idrinfo-\u003elock);\n1977:\t\t\t}\n1978:\t\t}\n1979:\t\tmutex_unlock(\u0026act_id_mutex);\n1980:\t\tup_read(\u0026net_rwsem);\n1981:\t\n1982:\t\treturn 0;\n1983:\t}\n1984:\t\n1985:\tstatic struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,\n1986:\t\t\t\t\t\t struct tc_action *actions[],\n1987:\t\t\t\t\t\t u32 portid, size_t attr_size,\n1988:\t\t\t\t\t\t struct netlink_ext_ack *extack)\n1989:\t{\n1990:\t\tstruct sk_buff *skb;\n1991:\t\n1992:\t\tskb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),\n1993:\t\t\t\t NLMSG_GOODSIZE), GFP_KERNEL);\n1994:\t\tif (!skb)\n1995:\t\t\treturn ERR_PTR(-ENOBUFS);\n1996:\t\n1997:\t\tif (tca_get_fill(skb, actions, portid, n-\u003enlmsg_seq, 0, RTM_DELACTION,\n1998:\t\t\t\t 0, 2, extack) \u003c= 0) {\n1999:\t\t\tNL_SET_ERR_MSG(extack, \"Failed to fill netlink TC action attributes\");\n2000:\t\t\tkfree_skb(skb);\n2001:\t\t\treturn ERR_PTR(-EINVAL);\n2002:\t\t}\n2003:\t\n2004:\t\treturn skb;\n2005:\t}\n2006:\t\n2007:\tstatic int tcf_del_notify(struct net *net, struct nlmsghdr *n,\n2008:\t\t\t\t struct tc_action *actions[], u32 portid,\n2009:\t\t\t\t size_t attr_size, struct netlink_ext_ack *extack)\n2010:\t{\n2011:\t\tstruct sk_buff *skb;\n2012:\t\tint ret;\n2013:\t\n2014:\t\tif (!rtnl_notify_needed(net, n-\u003enlmsg_flags, RTNLGRP_TC)) {\n2015:\t\t\tskb = NULL;\n2016:\t\t} else {\n2017:\t\t\tskb = tcf_del_notify_msg(net, n, actions, portid, attr_size,\n2018:\t\t\t\t\t\t extack);\n2019:\t\t\tif (IS_ERR(skb))\n2020:\t\t\t\treturn PTR_ERR(skb);\n2021:\t\t}\n2022:\t\n2023:\t\t/* now do the delete */\n2024:\t\tret = tcf_action_delete(net, actions);\n2025:\t\tif (ret \u003c 0) {\n2026:\t\t\tNL_SET_ERR_MSG(extack, \"Failed to delete TC action\");\n2027:\t\t\tkfree_skb(skb);\n2028:\t\t\treturn ret;\n2029:\t\t}\n2030:\t\n2031:\t\treturn rtnetlink_maybe_send(skb, net, portid, RTNLGRP_TC,\n2032:\t\t\t\t\t n-\u003enlmsg_flags \u0026 NLM_F_ECHO);\n2033:\t}\n2034:\t\n2035:\tstatic int\n2036:\ttca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,\n2037:\t\t u32 portid, int event, struct netlink_ext_ack *extack)\n2038:\t{\n2039:\t\tint i, ret;\n2040:\t\tstruct nlattr *tb[TCA_ACT_MAX_PRIO + 1];\n2041:\t\tstruct tc_action *act;\n2042:\t\tsize_t attr_size = 0;\n2043:\t\tstruct tc_action *actions[TCA_ACT_MAX_PRIO] = {};\n2044:\t\n2045:\t\tret = nla_parse_nested_deprecated(tb, TCA_ACT_MAX_PRIO, nla, NULL,\n2046:\t\t\t\t\t\t extack);\n2047:\t\tif (ret \u003c 0)\n2048:\t\t\treturn ret;\n2049:\t\n"
} |
| 55/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 13351 output: 38 thoughts: 28 Thoughts: Here's a summary of my thought process, as requested: **Diving into `act_api.c` for Action API Insights** Okay, so we're looking at some action API behavior, and my first instinct is to dive into the core implementation. I want to check out the details, the nitty-gritty of how these actions are defined and handled. It's time to check a specific chunk of the code. Let's target lines 2050 through 2120 within `net/sched/act_api.c`. That range should give me a good window into the areas I want to analyze, or so I think. I will now examine these lines. |
| 56/3 | 2026/09/22 05:26 | tool | read-file |
0mArgs:{
"File": "net/sched/act_api.c",
"FirstLine": 2050,
"LineCount": 70
}Results: {
"Contents": "2050:\t\tif (event == RTM_DELACTION \u0026\u0026 n-\u003enlmsg_flags \u0026 NLM_F_ROOT) {\n2051:\t\t\tif (tb[1])\n2052:\t\t\t\treturn tca_action_flush(net, tb[1], n, portid, extack);\n2053:\t\n2054:\t\t\tNL_SET_ERR_MSG(extack, \"Invalid netlink attributes while flushing TC action\");\n2055:\t\t\treturn -EINVAL;\n2056:\t\t}\n2057:\t\n2058:\t\tfor (i = 1; i \u003c= TCA_ACT_MAX_PRIO \u0026\u0026 tb[i]; i++) {\n2059:\t\t\tact = tcf_action_get_1(net, tb[i], n, portid, extack);\n2060:\t\t\tif (IS_ERR(act)) {\n2061:\t\t\t\tret = PTR_ERR(act);\n2062:\t\t\t\tgoto err;\n2063:\t\t\t}\n2064:\t\t\tattr_size += tcf_action_fill_size(act);\n2065:\t\t\tactions[i - 1] = act;\n2066:\t\t}\n2067:\t\n2068:\t\tattr_size = tcf_action_full_attrs_size(attr_size);\n2069:\t\n2070:\t\tif (event == RTM_GETACTION)\n2071:\t\t\tret = tcf_get_notify(net, portid, n, actions, attr_size, event,\n2072:\t\t\t\t\t extack);\n2073:\t\telse { /* delete */\n2074:\t\t\tret = tcf_del_notify(net, n, actions, portid, attr_size, extack);\n2075:\t\t\tif (ret)\n2076:\t\t\t\tgoto err;\n2077:\t\t\treturn 0;\n2078:\t\t}\n2079:\terr:\n2080:\t\ttcf_action_put_many(actions);\n2081:\t\treturn ret;\n2082:\t}\n2083:\t\n2084:\tstatic struct sk_buff *tcf_add_notify_msg(struct net *net, struct nlmsghdr *n,\n2085:\t\t\t\t\t\t struct tc_action *actions[],\n2086:\t\t\t\t\t\t u32 portid, size_t attr_size,\n2087:\t\t\t\t\t\t struct netlink_ext_ack *extack)\n2088:\t{\n2089:\t\tstruct sk_buff *skb;\n2090:\t\n2091:\t\tskb = alloc_skb(max(attr_size + tcf_action_warn_attr_size(extack),\n2092:\t\t\t\t NLMSG_GOODSIZE), GFP_KERNEL);\n2093:\t\tif (!skb)\n2094:\t\t\treturn ERR_PTR(-ENOBUFS);\n2095:\t\n2096:\t\tif (tca_get_fill(skb, actions, portid, n-\u003enlmsg_seq, n-\u003enlmsg_flags,\n2097:\t\t\t\t RTM_NEWACTION, 0, 0, extack) \u003c= 0) {\n2098:\t\t\tNL_SET_ERR_MSG(extack, \"Failed to fill netlink attributes while adding TC action\");\n2099:\t\t\tkfree_skb(skb);\n2100:\t\t\treturn ERR_PTR(-EINVAL);\n2101:\t\t}\n2102:\t\n2103:\t\treturn skb;\n2104:\t}\n2105:\t\n2106:\tstatic int tcf_add_notify(struct net *net, struct nlmsghdr *n,\n2107:\t\t\t\t struct tc_action *actions[], u32 portid,\n2108:\t\t\t\t size_t attr_size, struct netlink_ext_ack *extack)\n2109:\t{\n2110:\t\tstruct sk_buff *skb;\n2111:\t\n2112:\t\tif (!rtnl_notify_needed(net, n-\u003enlmsg_flags, RTNLGRP_TC)) {\n2113:\t\t\tskb = NULL;\n2114:\t\t} else {\n2115:\t\t\tskb = tcf_add_notify_msg(net, n, actions, portid, attr_size,\n2116:\t\t\t\t\t\t extack);\n2117:\t\t\tif (IS_ERR(skb))\n2118:\t\t\t\treturn PTR_ERR(skb);\n2119:\t\t}\n"
} |
| 57/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 14728 output: 30 thoughts: 56 Thoughts: **Analyzing This Commit** Alright, let's dive in. First, I need to understand the core issue this commit addresses. The most efficient way, of course, is to check the commit message or related pull request information. That's the first step - see if the context is readily available. Ah, I see a function call I recognize: `tca_get_fill()`. Interesting. Let's dig into that function's implementation directly to understand its role within the affected code. Understanding that function is key to properly understanding this change. |
| 58/3 | 2026/09/22 05:26 | tool | grepper |
0mArgs:{
"Expression": "tca_get_fill",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=470=static size_t tcf_action_full_attrs_size(size_t sz)\n--\nnet/sched/act_api.c-477-\nnet/sched/act_api.c:478:/* tca_get_fill() may append TCA_ROOT_EXT_WARN_MSG from extack-\u003e_msg */\nnet/sched/act_api.c-479-static size_t tcf_action_warn_attr_size(const struct netlink_ext_ack *extack)\n--\nnet/sched/act_api.c=1617=int tcf_action_copy_stats(struct sk_buff *skb, struct tc_action *p,\n--\nnet/sched/act_api.c-1667-\nnet/sched/act_api.c:1668:static int tca_get_fill(struct sk_buff *skb, struct tc_action *actions[],\nnet/sched/act_api.c-1669-\t\t\tu32 portid, u32 seq, u16 flags, int event, int bind,\n--\nnet/sched/act_api.c=1708=tcf_get_notify(struct net *net, u32 portid, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-1716-\t\treturn -ENOBUFS;\nnet/sched/act_api.c:1717:\tif (tca_get_fill(skb, actions, portid, n-\u003enlmsg_seq, 0, event,\nnet/sched/act_api.c-1718-\t\t\t 0, 1, NULL) \u003c= 0) {\n--\nnet/sched/act_api.c=1876=static struct sk_buff *tcf_reoffload_del_notify_msg(struct net *net,\n--\nnet/sched/act_api.c-1890-\nnet/sched/act_api.c:1891:\tif (tca_get_fill(skb, actions, 0, 0, 0, RTM_DELACTION, 0, 1, NULL) \u003c= 0) {\nnet/sched/act_api.c-1892-\t\tkfree_skb(skb);\n--\nnet/sched/act_api.c=1985=static struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-1996-\nnet/sched/act_api.c:1997:\tif (tca_get_fill(skb, actions, portid, n-\u003enlmsg_seq, 0, RTM_DELACTION,\nnet/sched/act_api.c-1998-\t\t\t 0, 2, extack) \u003c= 0) {\n--\nnet/sched/act_api.c=2084=static struct sk_buff *tcf_add_notify_msg(struct net *net, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-2095-\nnet/sched/act_api.c:2096:\tif (tca_get_fill(skb, actions, portid, n-\u003enlmsg_seq, n-\u003enlmsg_flags,\nnet/sched/act_api.c-2097-\t\t\t RTM_NEWACTION, 0, 0, extack) \u003c= 0) {\n"
} |
| 59/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 15801 output: 38 thoughts: 24 Thoughts: Here's my summary, as if I were thinking these thoughts: **Diving into the `tca_get_fill` Function** Okay, time to get into the weeds. Let's start by digging into `net/sched/act_api.c`. Specifically, I want to take a look at the `tca_get_fill` function. It's a key piece of the puzzle, and I'm interested in understanding how it's implemented. I'm expecting this to be the function responsible for populating the traffic control (TC) action attributes or data structures. I'll be looking for how it handles different action types, parses the user space data, and prepares it for the kernel's internal representation. I need to refresh my memory on the TC action infrastructure to interpret the purpose of the `tca_get_fill` function. I'm anticipating that it will handle populating the struct `tc_action` with information from a Netlink message. My focus will be on the parsing logic and the data structures involved. |
| 60/3 | 2026/09/22 05:26 | tool | read-file |
0mArgs:{
"File": "net/sched/act_api.c",
"FirstLine": 1665,
"LineCount": 45
}Results: {
"Contents": "1665:\t\treturn -1;\n1666:\t}\n1667:\t\n1668:\tstatic int tca_get_fill(struct sk_buff *skb, struct tc_action *actions[],\n1669:\t\t\t\tu32 portid, u32 seq, u16 flags, int event, int bind,\n1670:\t\t\t\tint ref, struct netlink_ext_ack *extack)\n1671:\t{\n1672:\t\tstruct tcamsg *t;\n1673:\t\tstruct nlmsghdr *nlh;\n1674:\t\tunsigned char *b = skb_tail_pointer(skb);\n1675:\t\tstruct nlattr *nest;\n1676:\t\n1677:\t\tnlh = nlmsg_put(skb, portid, seq, event, sizeof(*t), flags);\n1678:\t\tif (!nlh)\n1679:\t\t\tgoto out_nlmsg_trim;\n1680:\t\tt = nlmsg_data(nlh);\n1681:\t\tt-\u003etca_family = AF_UNSPEC;\n1682:\t\tt-\u003etca__pad1 = 0;\n1683:\t\tt-\u003etca__pad2 = 0;\n1684:\t\n1685:\t\tif (extack \u0026\u0026 extack-\u003e_msg \u0026\u0026\n1686:\t\t nla_put_string(skb, TCA_ROOT_EXT_WARN_MSG, extack-\u003e_msg))\n1687:\t\t\tgoto out_nlmsg_trim;\n1688:\t\n1689:\t\tnest = nla_nest_start_noflag(skb, TCA_ACT_TAB);\n1690:\t\tif (!nest)\n1691:\t\t\tgoto out_nlmsg_trim;\n1692:\t\n1693:\t\tif (tcf_action_dump(skb, actions, bind, ref, false) \u003c 0)\n1694:\t\t\tgoto out_nlmsg_trim;\n1695:\t\n1696:\t\tnla_nest_end(skb, nest);\n1697:\t\n1698:\t\tnlh-\u003enlmsg_len = skb_tail_pointer(skb) - b;\n1699:\t\n1700:\t\treturn skb-\u003elen;\n1701:\t\n1702:\tout_nlmsg_trim:\n1703:\t\tnlmsg_trim(skb, b);\n1704:\t\treturn -1;\n1705:\t}\n1706:\t\n1707:\tstatic int\n1708:\ttcf_get_notify(struct net *net, u32 portid, struct nlmsghdr *n,\n1709:\t\t struct tc_action *actions[], size_t attr_size, int event,\n"
} |
| 61/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 16814 output: 29 thoughts: 439 Thoughts: **My Analysis of a Potential Netlink Attribute Overflow**
Okay, let's break this down. I'm looking at `tca_get_fill()` and immediately see a potential issue. It's taking `TCA_ROOT_EXT_WARN_MSG` from `extack->_msg` and stuffing it into the SKB (Socket Buffer) if the `extack` pointer exists and `extack->_msg` is actually set.
Now, I recall that `tcf_del_notify_msg` and `tcf_add_notify_msg` were allocating this SKB using `alloc_skb()`, with a size determined by `max(attr_size, NLMSG_GOODSIZE)`. Hold on... `attr_size` seems to be derived from `tcf_action_fill_size(act)` and then `tcf_action_full_attrs_size(attr_size)`.
The alarm bells are starting to ring. What if `extack->_msg` was set *after* the initial size calculation, or what if `act->ops->get_fill_size` was missing or underestimated? Even worse, what if there's a disconnect between the reported size and the actual content?
If `attr_size` was underestimated – due to a missing `get_fill_size`, a calculation error, or perhaps attributes exceeding the `NLMSG_GOODSIZE` – and then `extack->_msg` was added, `tca_get_fill()` is going to choke. It'll likely fail because the SKB buffer just isn't big enough! And that failure leads to a `goto out_nlmsg_trim; return -1;`. I need to figure out how this is handled, and what the consequences are.
Let's look more closely. If `tca_get_fill()` returns a value that is <= 0:
I'm seeing that in `tcf_add_notify_msg`:
```c
if (tca_get_fill(...) <= 0) {
NL_SET_ERR_MSG(extack, "Failed to fill netlink attributes while adding TC action");
kfree_skb(skb);
return ERR_PTR(-EINVAL);
}
```
Okay, so it *should* fail gracefully, setting an error message and freeing the SKB, returning an EINVAL. However, what about the potential for a warning or an unhandled failure *before* it gets to this check?
Why was `get_fill_size` even implemented for these actions in the first place? It's clearly intended to prevent this. I need to trace back when that was introduced. A quick check of the git log for `act_api.c` and specifically for `get_fill_size` should shed some light on the history and the intended purpose. That'll provide context for why this function exists, and what problem it was supposed to solve. I need to understand the intent.
|
| 62/3 | 2026/09/22 05:26 | tool | grepper |
0mArgs:{
"Expression": "get_fill_size",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=487=static size_t tcf_action_fill_size(const struct tc_action *act)\n--\nnet/sched/act_api.c-490-\nnet/sched/act_api.c:491:\tif (act-\u003eops-\u003eget_fill_size)\nnet/sched/act_api.c:492:\t\treturn act-\u003eops-\u003eget_fill_size(act) + sz;\nnet/sched/act_api.c-493-\treturn sz;\n--\nnet/sched/act_bpf.c=384=static void tcf_bpf_cleanup(struct tc_action *act)\n--\nnet/sched/act_bpf.c-391-\nnet/sched/act_bpf.c:392:static size_t tcf_bpf_get_fill_size(const struct tc_action *act)\nnet/sched/act_bpf.c-393-{\n--\nnet/sched/act_bpf.c=417=static struct tc_action_ops act_bpf_ops __read_mostly = {\n--\nnet/sched/act_bpf.c-424-\t.init\t\t=\ttcf_bpf_init,\nnet/sched/act_bpf.c:425:\t.get_fill_size\t=\ttcf_bpf_get_fill_size,\nnet/sched/act_bpf.c-426-\t.size\t\t=\tsizeof(struct tcf_bpf),\n--\nnet/sched/act_connmark.c=229=static void tcf_connmark_cleanup(struct tc_action *a)\n--\nnet/sched/act_connmark.c-238-\nnet/sched/act_connmark.c:239:static size_t tcf_connmark_get_fill_size(const struct tc_action *act)\nnet/sched/act_connmark.c-240-{\n--\nnet/sched/act_connmark.c=244=static struct tc_action_ops act_connmark_ops = {\n--\nnet/sched/act_connmark.c-249-\t.dump\t\t=\ttcf_connmark_dump,\nnet/sched/act_connmark.c:250:\t.get_fill_size\t=\ttcf_connmark_get_fill_size,\nnet/sched/act_connmark.c-251-\t.init\t\t=\ttcf_connmark_init,\n--\nnet/sched/act_csum.c=674=static void tcf_csum_cleanup(struct tc_action *a)\n--\nnet/sched/act_csum.c-683-\nnet/sched/act_csum.c:684:static size_t tcf_csum_get_fill_size(const struct tc_action *act)\nnet/sched/act_csum.c-685-{\n--\nnet/sched/act_csum.c=708=static struct tc_action_ops act_csum_ops = {\n--\nnet/sched/act_csum.c-715-\t.cleanup\t= tcf_csum_cleanup,\nnet/sched/act_csum.c:716:\t.get_fill_size = tcf_csum_get_fill_size,\nnet/sched/act_csum.c-717-\t.offload_act_setup = tcf_csum_offload_act_setup,\n--\nnet/sched/act_ct.c=1636=static int tcf_ct_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_ct.c-1659-\nnet/sched/act_ct.c:1660:static size_t tcf_ct_get_fill_size(const struct tc_action *act)\nnet/sched/act_ct.c-1661-{\n--\nnet/sched/act_ct.c=1705=static struct tc_action_ops act_ct_ops = {\n--\nnet/sched/act_ct.c-1713-\t.stats_update\t=\ttcf_stats_update,\nnet/sched/act_ct.c:1714:\t.get_fill_size\t=\ttcf_ct_get_fill_size,\nnet/sched/act_ct.c-1715-\t.offload_act_setup =\ttcf_ct_offload_act_setup,\n--\nnet/sched/act_ctinfo.c=349=static void tcf_ctinfo_cleanup(struct tc_action *a)\n--\nnet/sched/act_ctinfo.c-358-\nnet/sched/act_ctinfo.c:359:static size_t tcf_ctinfo_get_fill_size(const struct tc_action *act)\nnet/sched/act_ctinfo.c-360-{\n--\nnet/sched/act_ctinfo.c=369=static struct tc_action_ops act_ctinfo_ops = {\n--\nnet/sched/act_ctinfo.c-376-\t.cleanup= tcf_ctinfo_cleanup,\nnet/sched/act_ctinfo.c:377:\t.get_fill_size = tcf_ctinfo_get_fill_size,\nnet/sched/act_ctinfo.c-378-\t.size\t= sizeof(struct tcf_ctinfo),\n--\nnet/sched/act_gact.c=190=static int tcf_gact_dump(struct sk_buff *skb, struct tc_action *a,\n--\nnet/sched/act_gact.c-230-\nnet/sched/act_gact.c:231:static size_t tcf_gact_get_fill_size(const struct tc_action *act)\nnet/sched/act_gact.c-232-{\n--\nnet/sched/act_gact.c=292=static struct tc_action_ops act_gact_ops = {\n--\nnet/sched/act_gact.c-299-\t.init\t\t=\ttcf_gact_init,\nnet/sched/act_gact.c:300:\t.get_fill_size\t=\ttcf_gact_get_fill_size,\nnet/sched/act_gact.c-301-\t.offload_act_setup =\ttcf_gact_offload_act_setup,\n--\nnet/sched/act_gate.c=672=static void tcf_gate_stats_update(struct tc_action *a, u64 bytes, u64 packets,\n--\nnet/sched/act_gate.c-681-\nnet/sched/act_gate.c:682:static size_t tcf_gate_get_fill_size(const struct tc_action *act)\nnet/sched/act_gate.c-683-{\n--\nnet/sched/act_gate.c=736=static struct tc_action_ops act_gate_ops = {\n--\nnet/sched/act_gate.c-744-\t.stats_update\t=\ttcf_gate_stats_update,\nnet/sched/act_gate.c:745:\t.get_fill_size\t=\ttcf_gate_get_fill_size,\nnet/sched/act_gate.c-746-\t.offload_act_setup =\ttcf_gate_offload_act_setup,\n--\nnet/sched/act_ife.c=881=TC_INDIRECT_SCOPE int tcf_ife_act(struct sk_buff *skb,\n--\nnet/sched/act_ife.c-904-\nnet/sched/act_ife.c:905:static size_t tcf_ife_get_fill_size(const struct tc_action *act)\nnet/sched/act_ife.c-906-{\n--\nnet/sched/act_ife.c=927=static struct tc_action_ops act_ife_ops = {\n--\nnet/sched/act_ife.c-934-\t.init = tcf_ife_init,\nnet/sched/act_ife.c:935:\t.get_fill_size = tcf_ife_get_fill_size,\nnet/sched/act_ife.c-936-\t.size =\tsizeof(struct tcf_ife_info),\n--\nnet/sched/act_mirred.c=591=tcf_mirred_get_dev(const struct tc_action *a,\n--\nnet/sched/act_mirred.c-607-\nnet/sched/act_mirred.c:608:static size_t tcf_mirred_get_fill_size(const struct tc_action *act)\nnet/sched/act_mirred.c-609-{\n--\nnet/sched/act_mirred.c=665=static struct tc_action_ops act_mirred_ops = {\n--\nnet/sched/act_mirred.c-673-\t.init\t\t=\ttcf_mirred_init,\nnet/sched/act_mirred.c:674:\t.get_fill_size\t=\ttcf_mirred_get_fill_size,\nnet/sched/act_mirred.c-675-\t.offload_act_setup =\ttcf_mirred_offload_act_setup,\n--\nnet/sched/act_mpls.c=382=static int tcf_mpls_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_mpls.c-440-\nnet/sched/act_mpls.c:441:static size_t tcf_mpls_get_fill_size(const struct tc_action *act)\nnet/sched/act_mpls.c-442-{\n--\nnet/sched/act_mpls.c=451=static struct tc_action_ops act_mpls_ops = {\n--\nnet/sched/act_mpls.c-456-\t.dump\t\t=\ttcf_mpls_dump,\nnet/sched/act_mpls.c:457:\t.get_fill_size\t=\ttcf_mpls_get_fill_size,\nnet/sched/act_mpls.c-458-\t.init\t\t=\ttcf_mpls_init,\n--\nnet/sched/act_nat.c=306=static void tcf_nat_cleanup(struct tc_action *a)\n--\nnet/sched/act_nat.c-315-\nnet/sched/act_nat.c:316:static size_t tcf_nat_get_fill_size(const struct tc_action *act)\nnet/sched/act_nat.c-317-{\n--\nnet/sched/act_nat.c=321=static struct tc_action_ops act_nat_ops = {\n--\nnet/sched/act_nat.c-326-\t.dump\t\t=\ttcf_nat_dump,\nnet/sched/act_nat.c:327:\t.get_fill_size\t=\ttcf_nat_get_fill_size,\nnet/sched/act_nat.c-328-\t.init\t\t=\ttcf_nat_init,\n--\nnet/sched/act_pedit.c=564=static int tcf_pedit_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_pedit.c-628-\nnet/sched/act_pedit.c:629:static size_t tcf_pedit_get_fill_size(const struct tc_action *act)\nnet/sched/act_pedit.c-630-{\n--\nnet/sched/act_pedit.c=652=static struct tc_action_ops act_pedit_ops = {\n--\nnet/sched/act_pedit.c-660-\t.init\t\t=\ttcf_pedit_init,\nnet/sched/act_pedit.c:661:\t.get_fill_size\t=\ttcf_pedit_get_fill_size,\nnet/sched/act_pedit.c-662-\t.offload_act_setup =\ttcf_pedit_offload_act_setup,\n--\nnet/sched/act_police.c=442=static int tcf_police_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_police.c-492-\nnet/sched/act_police.c:493:static size_t tcf_police_get_fill_size(const struct tc_action *act)\nnet/sched/act_police.c-494-{\n--\nnet/sched/act_police.c=508=static struct tc_action_ops act_police_ops = {\n--\nnet/sched/act_police.c-516-\t.cleanup\t=\ttcf_police_cleanup,\nnet/sched/act_police.c:517:\t.get_fill_size\t=\ttcf_police_get_fill_size,\nnet/sched/act_police.c-518-\t.offload_act_setup =\ttcf_police_offload_act_setup,\n--\nnet/sched/act_sample.c=296=static int tcf_sample_offload_act_setup(struct tc_action *act, void *entry_data,\n--\nnet/sched/act_sample.c-317-\nnet/sched/act_sample.c:318:static size_t tcf_sample_get_fill_size(const struct tc_action *act)\nnet/sched/act_sample.c-319-{\n--\nnet/sched/act_sample.c=326=static struct tc_action_ops act_sample_ops = {\n--\nnet/sched/act_sample.c-334-\t.cleanup = tcf_sample_cleanup,\nnet/sched/act_sample.c:335:\t.get_fill_size = tcf_sample_get_fill_size,\nnet/sched/act_sample.c-336-\t.get_psample_group = tcf_sample_get_group,\n--\nnet/sched/act_simple.c=61=static int reset_policy(struct tc_action *a, const struct nlattr *defdata,\n--\nnet/sched/act_simple.c-81-\nnet/sched/act_simple.c:82:static size_t tcf_simp_get_fill_size(const struct tc_action *act)\nnet/sched/act_simple.c-83-{\n--\nnet/sched/act_simple.c=207=static struct tc_action_ops act_simp_ops = {\n--\nnet/sched/act_simple.c-212-\t.dump\t\t=\ttcf_simp_dump,\nnet/sched/act_simple.c:213:\t.get_fill_size\t=\ttcf_simp_get_fill_size,\nnet/sched/act_simple.c-214-\t.cleanup\t=\ttcf_simp_release,\n--\nnet/sched/act_skbedit.c=348=static void tcf_skbedit_cleanup(struct tc_action *a)\n--\nnet/sched/act_skbedit.c-357-\nnet/sched/act_skbedit.c:358:static size_t tcf_skbedit_get_fill_size(const struct tc_action *act)\nnet/sched/act_skbedit.c-359-{\n--\nnet/sched/act_skbedit.c=418=static struct tc_action_ops act_skbedit_ops = {\n--\nnet/sched/act_skbedit.c-426-\t.cleanup\t=\ttcf_skbedit_cleanup,\nnet/sched/act_skbedit.c:427:\t.get_fill_size\t=\ttcf_skbedit_get_fill_size,\nnet/sched/act_skbedit.c-428-\t.offload_act_setup =\ttcf_skbedit_offload_act_setup,\n--\nnet/sched/act_skbmod.c=241=static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,\n--\nnet/sched/act_skbmod.c-281-\nnet/sched/act_skbmod.c:282:static size_t tcf_skbmod_get_fill_size(const struct tc_action *act)\nnet/sched/act_skbmod.c-283-{\n--\nnet/sched/act_skbmod.c=290=static struct tc_action_ops act_skbmod_ops = {\n--\nnet/sched/act_skbmod.c-295-\t.dump\t\t=\ttcf_skbmod_dump,\nnet/sched/act_skbmod.c:296:\t.get_fill_size\t=\ttcf_skbmod_get_fill_size,\nnet/sched/act_skbmod.c-297-\t.init\t\t=\ttcf_skbmod_init,\n--\nnet/sched/act_tunnel_key.c=860=static size_t tunnel_key_opts_fill_size(const struct ip_tunnel_info *info)\n--\nnet/sched/act_tunnel_key.c-885-\nnet/sched/act_tunnel_key.c:886:static size_t tunnel_key_get_fill_size(const struct tc_action *act)\nnet/sched/act_tunnel_key.c-887-{\n--\nnet/sched/act_tunnel_key.c=917=static struct tc_action_ops act_tunnel_key_ops = {\n--\nnet/sched/act_tunnel_key.c-924-\t.cleanup\t=\ttunnel_key_release,\nnet/sched/act_tunnel_key.c:925:\t.get_fill_size\t=\ttunnel_key_get_fill_size,\nnet/sched/act_tunnel_key.c-926-\t.offload_act_setup =\ttcf_tunnel_key_offload_act_setup,\n--\nnet/sched/act_vlan.c=336=static void tcf_vlan_stats_update(struct tc_action *a, u64 bytes, u64 packets,\n--\nnet/sched/act_vlan.c-345-\nnet/sched/act_vlan.c:346:static size_t tcf_vlan_get_fill_size(const struct tc_action *act)\nnet/sched/act_vlan.c-347-{\n--\nnet/sched/act_vlan.c=416=static struct tc_action_ops act_vlan_ops = {\n--\nnet/sched/act_vlan.c-424-\t.stats_update\t=\ttcf_vlan_stats_update,\nnet/sched/act_vlan.c:425:\t.get_fill_size\t=\ttcf_vlan_get_fill_size,\nnet/sched/act_vlan.c-426-\t.offload_act_setup =\ttcf_vlan_offload_act_setup,\n"
} |
| 63/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 22801 output: 31 thoughts: 99 Thoughts: **Analyzing Netlink Attribute Sizes in tc Action Dumps** Okay, let's break this down. My goal is to understand how well the `get_fill_size` callbacks in `act_api` are reflecting the actual netlink attribute sizes generated by the action's `dump` functions. So, first thing, I need to focus on the `act_api` code. Specifically, I'm looking for the `get_fill_size` callback that reports the maximum netlink attribute size an action's `dump` function uses. Now, I'm going to dig into the `dump` functions within the actions that are part of the changes. This is where the rubber meets the road. I'll need to compare what the `dump` functions actually output in terms of attributes with what `get_fill_size` claims they can handle. This way, I can validate the `get_fill_size` reports. Starting with `act_connmark.c`... let's get into the specifics of what that `tcf_connmark_dump` function is spitting out. |
| 64/3 | 2026/09/22 05:26 | tool | grepper |
0mArgs:{
"Expression": "tcf_connmark_dump",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_connmark.c=98=static int tcf_connmark_init(struct net *net, struct nlattr *nla,\n--\nnet/sched/act_connmark.c-191-\nnet/sched/act_connmark.c:192:static inline int tcf_connmark_dump(struct sk_buff *skb, struct tc_action *a,\nnet/sched/act_connmark.c-193-\t\t\t\t int bind, int ref)\n--\nnet/sched/act_connmark.c=244=static struct tc_action_ops act_connmark_ops = {\n--\nnet/sched/act_connmark.c-248-\t.act\t\t=\ttcf_connmark_act,\nnet/sched/act_connmark.c:249:\t.dump\t\t=\ttcf_connmark_dump,\nnet/sched/act_connmark.c-250-\t.get_fill_size\t=\ttcf_connmark_get_fill_size,\n"
} |
| 65/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 23431 output: 38 thoughts: 26 Thoughts: Here's my summary, as though I'm reading and thinking about the code: **Diving into `tcf_connmark_dump`** Alright, let's get into the guts of the connection marking action in the networking stack. I'm focusing on the `tcf_connmark_dump` function within `net/sched/act_connmark.c`. This is where the details of how this action's configuration gets exposed, likely for inspection and modification through tools like `tc` are. I need to understand what information this function reveals to the user. I expect it'll involve dumping the connection marking rule's details: things like the connection mark value itself (the actual mark), the mask that's applied to the existing mark (and how it allows for modification of a subset of the bits). I'm curious to see how the code structures the output. I'm guessing it will generate a standardized format, probably using Netlink attributes so that `tc` (or any user-space application) can cleanly parse the configuration. I want to see how much of the configuration is exposed; does it include any internal state, or just the parameters the user explicitly set? I expect to see the basic connection marking values, but depending on the implementation, there might be more nuanced details about how the connection is tracked or managed, if this is an advanced configuration. The goal is to see the exact structure the code will provide to the user, through this dump function. Let's see how well it exposes the connection mark configuration. |
| 66/3 | 2026/09/22 05:26 | tool | read-file |
0mArgs:{
"File": "net/sched/act_connmark.c",
"FirstLine": 192,
"LineCount": 40
}Results: {
"Contents": " 192:\tstatic inline int tcf_connmark_dump(struct sk_buff *skb, struct tc_action *a,\n 193:\t\t\t\t\t int bind, int ref)\n 194:\t{\n 195:\t\tconst struct tcf_connmark_info *ci = to_connmark(a);\n 196:\t\tunsigned char *b = skb_tail_pointer(skb);\n 197:\t\tconst struct tcf_connmark_parms *parms;\n 198:\t\tstruct tc_connmark opt;\n 199:\t\tstruct tcf_t t;\n 200:\t\n 201:\t\tmemset(\u0026opt, 0, sizeof(opt));\n 202:\t\n 203:\t\topt.index = ci-\u003etcf_index;\n 204:\t\topt.refcnt = refcount_read(\u0026ci-\u003etcf_refcnt) - ref;\n 205:\t\topt.bindcnt = atomic_read(\u0026ci-\u003etcf_bindcnt) - bind;\n 206:\t\n 207:\t\trcu_read_lock();\n 208:\t\tparms = rcu_dereference(ci-\u003eparms);\n 209:\t\n 210:\t\topt.action = parms-\u003eaction;\n 211:\t\topt.zone = parms-\u003ezone;\n 212:\t\tif (nla_put(skb, TCA_CONNMARK_PARMS, sizeof(opt), \u0026opt))\n 213:\t\t\tgoto nla_put_failure;\n 214:\t\n 215:\t\ttcf_tm_dump(\u0026t, \u0026ci-\u003etcf_tm);\n 216:\t\tif (nla_put_64bit(skb, TCA_CONNMARK_TM, sizeof(t), \u0026t,\n 217:\t\t\t\t TCA_CONNMARK_PAD))\n 218:\t\t\tgoto nla_put_failure;\n 219:\t\trcu_read_unlock();\n 220:\t\n 221:\t\treturn skb-\u003elen;\n 222:\t\n 223:\tnla_put_failure:\n 224:\t\trcu_read_unlock();\n 225:\t\tnlmsg_trim(skb, b);\n 226:\t\treturn -1;\n 227:\t}\n 228:\t\n 229:\tstatic void tcf_connmark_cleanup(struct tc_action *a)\n 230:\t{\n 231:\t\tstruct tcf_connmark_info *ci = to_connmark(a);\n"
} |
| 67/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 24485 output: 34 thoughts: 44 Thoughts: Here's my attempt at summarizing the thought process, as if I were having them: **Dissecting Shared Attribute Sizing** Okay, hold on a second. I need to make sure I'm crystal clear on this. When `tcf_action_shared_attrs_size(act)` is called, what precisely *is* being included? I'm dealing with the size of shared attributes and I need to be 100% accurate. Let me quickly jump into `act_api.c` and take a look at the `tcf_action_shared_attrs_size` function. I need to refresh my understanding and make sure I haven't missed a key aspect of how this sizing is handled. Time to dive into the code! |
| 68/3 | 2026/09/22 05:26 | tool | grepper |
0mArgs:{
"Expression": "tcf_action_shared_attrs_size",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=428=EXPORT_SYMBOL(tcf_idr_release);\nnet/sched/act_api.c-429-\nnet/sched/act_api.c:430:static size_t tcf_action_shared_attrs_size(const struct tc_action *act)\nnet/sched/act_api.c-431-{\n--\nnet/sched/act_api.c=487=static size_t tcf_action_fill_size(const struct tc_action *act)\nnet/sched/act_api.c-488-{\nnet/sched/act_api.c:489:\tsize_t sz = tcf_action_shared_attrs_size(act);\nnet/sched/act_api.c-490-\n"
} |
| 69/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 24933 output: 37 thoughts: 28 Thoughts: Here's a first-person summary, tailored as requested: **Diving into `act_api.c` - Checking `tcf_action_shared_attrs_size`** Okay, let's get down to brass tacks. I'm going to take a look at the `net/sched/act_api.c` file. Specifically, I need to understand how shared attributes are handled within the traffic control action framework. The first item on the agenda is to check out `tcf_action_shared_attrs_size`. I need to figure out how this size is determined and used, because the shared attributes are a critical component for efficient and reliable operation of different actions that I may be implementing. Understanding the implications will be critical to designing a new action. |
| 70/3 | 2026/09/22 05:26 | tool | read-file |
0mArgs:{
"File": "net/sched/act_api.c",
"FirstLine": 430,
"LineCount": 45
}Results: {
"Contents": " 430:\tstatic size_t tcf_action_shared_attrs_size(const struct tc_action *act)\n 431:\t{\n 432:\t\tstruct tc_cookie *user_cookie;\n 433:\t\tu32 cookie_len = 0;\n 434:\t\n 435:\t\trcu_read_lock();\n 436:\t\tuser_cookie = rcu_dereference(act-\u003euser_cookie);\n 437:\t\n 438:\t\tif (user_cookie)\n 439:\t\t\tcookie_len = nla_total_size(user_cookie-\u003elen);\n 440:\t\trcu_read_unlock();\n 441:\t\n 442:\t\treturn nla_total_size(0) /* action number nested */\n 443:\t\t\t+ nla_total_size(IFNAMSIZ) /* TCA_ACT_KIND */\n 444:\t\t\t+ cookie_len /* TCA_ACT_COOKIE */\n 445:\t\t\t+ nla_total_size(sizeof(struct nla_bitfield32)) /* TCA_ACT_HW_STATS */\n 446:\t\t\t/* TCA_ACT_USED_HW_STATS */\n 447:\t\t\t+ nla_total_size(sizeof(struct nla_bitfield32))\n 448:\t\t\t+ nla_total_size(sizeof(u32)) /* TCA_ACT_IN_HW_COUNT */\n 449:\t\t\t+ nla_total_size(0) /* TCA_ACT_STATS nested */\n 450:\t\t\t+ nla_total_size(sizeof(struct nla_bitfield32)) /* TCA_ACT_FLAGS */\n 451:\t\t\t/* TCA_STATS_BASIC */\n 452:\t\t\t+ nla_total_size_64bit(sizeof(struct gnet_stats_basic))\n 453:\t\t\t/* TCA_STATS_BASIC_HW */\n 454:\t\t\t+ nla_total_size_64bit(sizeof(struct gnet_stats_basic))\n 455:\t\t\t/* TCA_STATS_PKT64, emitted by both of the basic copies above */\n 456:\t\t\t+ 2 * nla_total_size_64bit(sizeof(u64))\n 457:\t\t\t/* TCA_STATS_RATE_EST */\n 458:\t\t\t+ nla_total_size_64bit(sizeof(struct gnet_stats_rate_est))\n 459:\t\t\t/* TCA_STATS_RATE_EST64 */\n 460:\t\t\t+ nla_total_size_64bit(sizeof(struct gnet_stats_rate_est64))\n 461:\t\t\t/* TCA_STATS_QUEUE */\n 462:\t\t\t+ nla_total_size_64bit(sizeof(struct gnet_stats_queue))\n 463:\t\t\t+ nla_total_size(0) /* TCA_ACT_OPTIONS nested */\n 464:\t\t\t/* TCA_GACT_TM; actions dump their tcf_t with nla_put_64bit(),\n 465:\t\t\t * which may emit an extra NLA_PAD attribute.\n 466:\t\t\t */\n 467:\t\t\t+ nla_total_size_64bit(sizeof(struct tcf_t));\n 468:\t}\n 469:\t\n 470:\tstatic size_t tcf_action_full_attrs_size(size_t sz)\n 471:\t{\n 472:\t\treturn NLMSG_HDRLEN /* struct nlmsghdr */\n 473:\t\t\t+ sizeof(struct tcamsg)\n 474:\t\t\t+ nla_total_size(0) /* TCA_ACT_TAB nested */\n"
} |
| 71/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 26098 output: 31 thoughts: 164 Thoughts: **Analyzing Connection Mark Size Calculations** Okay, so I'm digging into how we're calculating sizes for our traffic control actions, specifically around the `connmark` and `mirred` modules. It seems like the existing `tcf_action_shared_attrs_size` function should already be accounting for the shared attributes, including the `TCA_GACT_TM` tag (which corresponds to `tcf_t`). And, looking at the `tcf_connmark_dump` function, it specifically handles dumping both `TCA_CONNMARK_PARMS` and the `TCA_CONNMARK_TM` tag (again, our `tcf_t`). This tells me that the `get_fill_size` function for the `connmark` action *should* only need to account for the `TCA_CONNMARK_PARMS` attribute. I need to make sure I am correct, as otherwise it could lead to an inaccurate size being used, creating unexpected side-effects. To be sure, I'm going to quickly cross-check the size calculation for `act_mirred.c` as a point of comparison. Here, it seems like we have `nla_total_size(sizeof(struct tc_mirred)) + nla_total_size(sizeof(u32)); /* TCA_MIRRED_BLOCKID */`. I'll also want to review `tcf_mirred_dump` to have a full picture and compare. This should give me a solid confirmation of the size calculations. |
| 72/3 | 2026/09/22 05:26 | tool | grepper |
0mArgs:{
"Expression": "tcf_mirred_dump",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_mirred.c=502=static void tcf_stats_update(struct tc_action *a, u64 bytes, u64 packets,\n--\nnet/sched/act_mirred.c-511-\nnet/sched/act_mirred.c:512:static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,\nnet/sched/act_mirred.c-513-\t\t\t int ref)\n--\nnet/sched/act_mirred.c=665=static struct tc_action_ops act_mirred_ops = {\n--\nnet/sched/act_mirred.c-670-\t.stats_update\t=\ttcf_stats_update,\nnet/sched/act_mirred.c:671:\t.dump\t\t=\ttcf_mirred_dump,\nnet/sched/act_mirred.c-672-\t.cleanup\t=\ttcf_mirred_release,\n"
} |
| 73/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 26884 output: 38 thoughts: 22 Thoughts: Here's my take on those thoughts: **Analyzing `tcf_mirred_dump` within `act_mirred.c`** Okay, time to dive into `act_mirred.c` and specifically, that `tcf_mirred_dump` function. I need to refresh my memory on the internal workings of the mirrored traffic control actions. This function is the key to understanding how we're currently dumping the state, which is crucial for debugging and, potentially, for integrating with new reporting systems. I need to quickly identify the data structures that are being exposed and make sure I fully understand their interpretation. I'm hoping it's well-documented internally, although, I might need to cross-reference with the broader kernel documentation if necessary. Let's see if this dump gives me the granularity I'm looking for. |
| 74/3 | 2026/09/22 05:26 | tool | read-file |
0mArgs:{
"File": "net/sched/act_mirred.c",
"FirstLine": 512,
"LineCount": 45
}Results: {
"Contents": " 512:\tstatic int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,\n 513:\t\t\t\t int ref)\n 514:\t{\n 515:\t\tunsigned char *b = skb_tail_pointer(skb);\n 516:\t\tstruct tcf_mirred *m = to_mirred(a);\n 517:\t\tstruct tc_mirred opt = {\n 518:\t\t\t.index = m-\u003etcf_index,\n 519:\t\t\t.refcnt = refcount_read(\u0026m-\u003etcf_refcnt) - ref,\n 520:\t\t\t.bindcnt = atomic_read(\u0026m-\u003etcf_bindcnt) - bind,\n 521:\t\t};\n 522:\t\tstruct net_device *dev;\n 523:\t\tstruct tcf_t t;\n 524:\t\tu32 blockid;\n 525:\t\n 526:\t\tspin_lock_bh(\u0026m-\u003etcf_lock);\n 527:\t\topt.action = m-\u003etcf_action;\n 528:\t\topt.eaction = m-\u003etcfm_eaction;\n 529:\t\tdev = tcf_mirred_dev_dereference(m);\n 530:\t\tif (dev)\n 531:\t\t\topt.ifindex = dev-\u003eifindex;\n 532:\t\n 533:\t\tif (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), \u0026opt))\n 534:\t\t\tgoto nla_put_failure;\n 535:\t\n 536:\t\tblockid = m-\u003etcfm_blockid;\n 537:\t\tif (blockid \u0026\u0026 nla_put_u32(skb, TCA_MIRRED_BLOCKID, blockid))\n 538:\t\t\tgoto nla_put_failure;\n 539:\t\n 540:\t\ttcf_tm_dump(\u0026t, \u0026m-\u003etcf_tm);\n 541:\t\tif (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), \u0026t, TCA_MIRRED_PAD))\n 542:\t\t\tgoto nla_put_failure;\n 543:\t\tspin_unlock_bh(\u0026m-\u003etcf_lock);\n 544:\t\n 545:\t\treturn skb-\u003elen;\n 546:\t\n 547:\tnla_put_failure:\n 548:\t\tspin_unlock_bh(\u0026m-\u003etcf_lock);\n 549:\t\tnlmsg_trim(skb, b);\n 550:\t\treturn -1;\n 551:\t}\n 552:\t\n 553:\tstatic int mirred_device_event(struct notifier_block *unused,\n 554:\t\t\t\t unsigned long event, void *ptr)\n 555:\t{\n 556:\t\tstruct net_device *dev = netdev_notifier_info_to_dev(ptr);\n"
} |
| 75/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 27900 output: 31 thoughts: 129 Thoughts: **Analyzing the Act_Mirred and Act_Mpls Code for Mirroring Functionality** Okay, so I'm looking at how mirroring is implemented. `tcf_mirred_dump` dumps out the parameters for the mirror action, which includes the `TCA_MIRRED_PARMS` and *potentially* `TCA_MIRRED_BLOCKID`, and crucially, the timestamp `TCA_MIRRED_TM` which is part of that `tcf_t` struct, the common part. I need to make a note of that shared timestamp. Before, in `act_mirred.c`, I noticed a potential oversight. The `get_fill_size` function only calculated the size for the base `tc_mirred` struct, specifically `nla_total_size(sizeof(struct tc_mirred))`, but crucially *didn't* include the size for `TCA_MIRRED_BLOCKID`, calculated as `nla_total_size(sizeof(u32))`. This omission is definitely something to revisit. Now, my next step is to switch gears and check out what's going on in `act_mpls.c`. I need to compare the mirror functionality there with the `act_mirred.c` code to see if there are any inconsistencies or potential improvements. I need to consider all the pieces of this puzzle. |
| 76/3 | 2026/09/22 05:26 | tool | grepper |
0mArgs:{
"Expression": "tcf_mpls_dump",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_mpls.c=318=static void tcf_mpls_cleanup(struct tc_action *a)\n--\nnet/sched/act_mpls.c-327-\nnet/sched/act_mpls.c:328:static int tcf_mpls_dump(struct sk_buff *skb, struct tc_action *a,\nnet/sched/act_mpls.c-329-\t\t\t int bind, int ref)\n--\nnet/sched/act_mpls.c=451=static struct tc_action_ops act_mpls_ops = {\n--\nnet/sched/act_mpls.c-455-\t.act\t\t=\ttcf_mpls_act,\nnet/sched/act_mpls.c:456:\t.dump\t\t=\ttcf_mpls_dump,\nnet/sched/act_mpls.c-457-\t.get_fill_size\t=\ttcf_mpls_get_fill_size,\n"
} |
| 77/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 28615 output: 38 thoughts: 26 Thoughts: Here's my summary, as though I'm reading and processing the provided code reference: **Diving into the MPLS Dump** Okay, time to crack open `tcf_mpls_dump` within `net/sched/act_mpls.c`. Let's see what's going on here. This function is obviously critical, a real deep dive into how the MPLS classifier is doing its work. I expect it's going to tell me exactly how the MPLS action module is dumping its internal state for debugging or monitoring purposes. Probably for some kind of user space interaction or reporting. Likely, it constructs some kind of data structure, maybe a netlink message or similar, to provide information about the current configuration and the classifier's active rules or states. I'm keen to see how they've handled the complexities of MPLS and potentially how the relevant information is structured for easy consumption. This is where the rubber meets the road in terms of understanding the module's real-time operational status. Let's see if this follows the standard kernel dump patterns, or if they have some unique approach for this specific module. Let's get reading and see what insights this function has to offer. |
| 78/3 | 2026/09/22 05:26 | tool | read-file |
0mArgs:{
"File": "net/sched/act_mpls.c",
"FirstLine": 328,
"LineCount": 45
}Results: {
"Contents": " 328:\tstatic int tcf_mpls_dump(struct sk_buff *skb, struct tc_action *a,\n 329:\t\t\t\t int bind, int ref)\n 330:\t{\n 331:\t\tunsigned char *b = skb_tail_pointer(skb);\n 332:\t\tconst struct tcf_mpls *m = to_mpls(a);\n 333:\t\tconst struct tcf_mpls_params *p;\n 334:\t\tstruct tc_mpls opt = {\n 335:\t\t\t.index = m-\u003etcf_index,\n 336:\t\t\t.refcnt = refcount_read(\u0026m-\u003etcf_refcnt) - ref,\n 337:\t\t\t.bindcnt = atomic_read(\u0026m-\u003etcf_bindcnt) - bind,\n 338:\t\t};\n 339:\t\tstruct tcf_t t;\n 340:\t\n 341:\t\trcu_read_lock();\n 342:\t\tp = rcu_dereference(m-\u003empls_p);\n 343:\t\topt.m_action = p-\u003etcfm_action;\n 344:\t\topt.action = p-\u003eaction;\n 345:\t\n 346:\t\tif (nla_put(skb, TCA_MPLS_PARMS, sizeof(opt), \u0026opt))\n 347:\t\t\tgoto nla_put_failure;\n 348:\t\n 349:\t\tif (p-\u003etcfm_label != ACT_MPLS_LABEL_NOT_SET \u0026\u0026\n 350:\t\t nla_put_u32(skb, TCA_MPLS_LABEL, p-\u003etcfm_label))\n 351:\t\t\tgoto nla_put_failure;\n 352:\t\n 353:\t\tif (p-\u003etcfm_tc != ACT_MPLS_TC_NOT_SET \u0026\u0026\n 354:\t\t nla_put_u8(skb, TCA_MPLS_TC, p-\u003etcfm_tc))\n 355:\t\t\tgoto nla_put_failure;\n 356:\t\n 357:\t\tif (p-\u003etcfm_ttl \u0026\u0026 nla_put_u8(skb, TCA_MPLS_TTL, p-\u003etcfm_ttl))\n 358:\t\t\tgoto nla_put_failure;\n 359:\t\n 360:\t\tif (p-\u003etcfm_bos != ACT_MPLS_BOS_NOT_SET \u0026\u0026\n 361:\t\t nla_put_u8(skb, TCA_MPLS_BOS, p-\u003etcfm_bos))\n 362:\t\t\tgoto nla_put_failure;\n 363:\t\n 364:\t\tif (nla_put_be16(skb, TCA_MPLS_PROTO, p-\u003etcfm_proto))\n 365:\t\t\tgoto nla_put_failure;\n 366:\t\n 367:\t\ttcf_tm_dump(\u0026t, \u0026m-\u003etcf_tm);\n 368:\t\n 369:\t\tif (nla_put_64bit(skb, TCA_MPLS_TM, sizeof(t), \u0026t, TCA_MPLS_PAD))\n 370:\t\t\tgoto nla_put_failure;\n 371:\t\n 372:\t\trcu_read_unlock();\n"
} |
| 79/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 29791 output: 30 thoughts: 130 Thoughts: **Analyzing Attribute Sizes for MPLS Traffic Control** Okay, so I'm looking at `act_mpls.c` here. I see the calculation for the total Netlink attribute size used for MPLS parameters: `nla_total_size(sizeof(struct tc_mpls)) /* TCA_MPLS_PARMS */ + nla_total_size(sizeof(u32)) + nla_total_size(sizeof(u8)) + nla_total_size(sizeof(u8)) + nla_total_size(sizeof(u8)) + nla_total_size(sizeof(u16))`. That makes sense; it covers the base `struct tc_mpls`, then adds sizes for individual fields – I'm assuming those are the various MPLS label components. This should directly correspond to what's being dumped out in `tcf_mpls_dump`, so it's good to confirm that the attribute layout is consistent during both the addition and the reading. Now, I'll switch my focus over to `act_nat.c` to look at Netfilter NAT-related actions and attributes... |
| 80/3 | 2026/09/22 05:26 | tool | grepper |
0mArgs:{
"Expression": "tcf_nat_dump",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_nat.c=115=TC_INDIRECT_SCOPE int tcf_nat_act(struct sk_buff *skb,\n--\nnet/sched/act_nat.c-266-\nnet/sched/act_nat.c:267:static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,\nnet/sched/act_nat.c-268-\t\t\tint bind, int ref)\n--\nnet/sched/act_nat.c=321=static struct tc_action_ops act_nat_ops = {\n--\nnet/sched/act_nat.c-325-\t.act\t\t=\ttcf_nat_act,\nnet/sched/act_nat.c:326:\t.dump\t\t=\ttcf_nat_dump,\nnet/sched/act_nat.c-327-\t.get_fill_size\t=\ttcf_nat_get_fill_size,\n"
} |
| 81/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 30449 output: 37 thoughts: 24 Thoughts: Here's my take: **Investigating the `tcf_nat_dump` Function** Alright, let's dive into this `tcf_nat_dump` function. I need to refresh my memory on the NAT action module within the networking scheduler, so I'm heading directly to `net/sched/act_nat.c`. Hopefully, the function's name is descriptive enough and will make it relatively straightforward to understand how the NAT configuration is presented or exported. I anticipate this function will be essential for debugging, monitoring, or even configuration validation of the NAT actions. I will focus on understanding how the function structures and outputs the relevant NAT parameters such as addresses, port mappings, and other essential connection details. |
| 82/3 | 2026/09/22 05:26 | tool | read-file |
0mArgs:{
"File": "net/sched/act_nat.c",
"FirstLine": 267,
"LineCount": 45
}Results: {
"Contents": " 267:\tstatic int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,\n 268:\t\t\t\tint bind, int ref)\n 269:\t{\n 270:\t\tunsigned char *b = skb_tail_pointer(skb);\n 271:\t\tconst struct tcf_nat *p = to_tcf_nat(a);\n 272:\t\tconst struct tcf_nat_parms *parms;\n 273:\t\tstruct tc_nat opt = {\n 274:\t\t\t.index = p-\u003etcf_index,\n 275:\t\t\t.refcnt = refcount_read(\u0026p-\u003etcf_refcnt) - ref,\n 276:\t\t\t.bindcnt = atomic_read(\u0026p-\u003etcf_bindcnt) - bind,\n 277:\t\t};\n 278:\t\tstruct tcf_t t;\n 279:\t\n 280:\t\trcu_read_lock();\n 281:\t\n 282:\t\tparms = rcu_dereference(p-\u003eparms);\n 283:\t\n 284:\t\topt.action = parms-\u003eaction;\n 285:\t\topt.old_addr = parms-\u003eold_addr;\n 286:\t\topt.new_addr = parms-\u003enew_addr;\n 287:\t\topt.mask = parms-\u003emask;\n 288:\t\topt.flags = parms-\u003eflags;\n 289:\t\n 290:\t\tif (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), \u0026opt))\n 291:\t\t\tgoto nla_put_failure;\n 292:\t\n 293:\t\ttcf_tm_dump(\u0026t, \u0026p-\u003etcf_tm);\n 294:\t\tif (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), \u0026t, TCA_NAT_PAD))\n 295:\t\t\tgoto nla_put_failure;\n 296:\t\trcu_read_unlock();\n 297:\t\n 298:\t\treturn skb-\u003elen;\n 299:\t\n 300:\tnla_put_failure:\n 301:\t\trcu_read_unlock();\n 302:\t\tnlmsg_trim(skb, b);\n 303:\t\treturn -1;\n 304:\t}\n 305:\t\n 306:\tstatic void tcf_nat_cleanup(struct tc_action *a)\n 307:\t{\n 308:\t\tstruct tcf_nat *p = to_tcf_nat(a);\n 309:\t\tstruct tcf_nat_parms *parms;\n 310:\t\n 311:\t\tparms = rcu_dereference_protected(p-\u003eparms, 1);\n"
} |
| 83/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 31404 output: 30 thoughts: 71 Thoughts: Here's my summary, as though I'm thinking through this process: **Diving into the NAT Module** Okay, so I'm looking into how the NAT module within the traffic control framework is structured, and it seems like `tcf_nat_dump` is responsible for extracting the relevant parameters. Specifically, it's pulling out the `TCA_NAT_PARMS` and `TCA_NAT_TM` attributes. That makes sense; those are the key configuration and time management components for Network Address Translation. I need to remember that. Then, I see `tcf_nat_get_fill_size` returning the total size calculation using `nla_total_size` on the `sizeof(struct tc_nat)`. Okay, so it’s calculating the size needed for this NAT configuration. It's using netlink's size functions, as expected, ensuring proper alignment and padding for the attributes. Makes perfect sense. Now, I need to understand how this is actually put into practice. The next logical step would be to see how this code interacts with actual user configurations, so let's dig into `act_simple.c` next. This should reveal how the information provided by the NAT module is used at a high level. |
| 84/3 | 2026/09/22 05:26 | tool | grepper |
0mArgs:{
"Expression": "tcf_simp_dump",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_simple.c=93=static int tcf_simp_init(struct net *net, struct nlattr *nla,\n--\nnet/sched/act_simple.c-175-\nnet/sched/act_simple.c:176:static int tcf_simp_dump(struct sk_buff *skb, struct tc_action *a,\nnet/sched/act_simple.c-177-\t\t\t int bind, int ref)\n--\nnet/sched/act_simple.c=207=static struct tc_action_ops act_simp_ops = {\n--\nnet/sched/act_simple.c-211-\t.act\t\t=\ttcf_simp_act,\nnet/sched/act_simple.c:212:\t.dump\t\t=\ttcf_simp_dump,\nnet/sched/act_simple.c-213-\t.get_fill_size\t=\ttcf_simp_get_fill_size,\n"
} |
| 85/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 32023 output: 37 thoughts: 24 Thoughts: Here's my summary, as if I were thinking these thoughts: **Examining the `tcf_simp_dump` Function** Okay, time to dive in. I need to get a better handle on how this `act_simple` action works. Let's start with a crucial piece: I'm going to take a look at the `tcf_simp_dump` function. I'll find it in the `net/sched/act_simple.c` file. This dump function is key for inspecting and understanding the current state and parameters of the simple action classifier. It'll give me the insights I need to troubleshoot or extend it correctly. |
| 86/3 | 2026/09/22 05:26 | tool | read-file |
0mArgs:{
"File": "net/sched/act_simple.c",
"FirstLine": 176,
"LineCount": 35
}Results: {
"Contents": " 176:\tstatic int tcf_simp_dump(struct sk_buff *skb, struct tc_action *a,\n 177:\t\t\t\t int bind, int ref)\n 178:\t{\n 179:\t\tunsigned char *b = skb_tail_pointer(skb);\n 180:\t\tstruct tcf_defact *d = to_defact(a);\n 181:\t\tstruct tc_defact opt = {\n 182:\t\t\t.index = d-\u003etcf_index,\n 183:\t\t\t.refcnt = refcount_read(\u0026d-\u003etcf_refcnt) - ref,\n 184:\t\t\t.bindcnt = atomic_read(\u0026d-\u003etcf_bindcnt) - bind,\n 185:\t\t};\n 186:\t\tstruct tcf_t t;\n 187:\t\n 188:\t\tspin_lock_bh(\u0026d-\u003etcf_lock);\n 189:\t\topt.action = d-\u003etcf_action;\n 190:\t\tif (nla_put(skb, TCA_DEF_PARMS, sizeof(opt), \u0026opt) ||\n 191:\t\t nla_put_string(skb, TCA_DEF_DATA, d-\u003etcfd_defdata))\n 192:\t\t\tgoto nla_put_failure;\n 193:\t\n 194:\t\ttcf_tm_dump(\u0026t, \u0026d-\u003etcf_tm);\n 195:\t\tif (nla_put_64bit(skb, TCA_DEF_TM, sizeof(t), \u0026t, TCA_DEF_PAD))\n 196:\t\t\tgoto nla_put_failure;\n 197:\t\tspin_unlock_bh(\u0026d-\u003etcf_lock);\n 198:\t\n 199:\t\treturn skb-\u003elen;\n 200:\t\n 201:\tnla_put_failure:\n 202:\t\tspin_unlock_bh(\u0026d-\u003etcf_lock);\n 203:\t\tnlmsg_trim(skb, b);\n 204:\t\treturn -1;\n 205:\t}\n 206:\t\n 207:\tstatic struct tc_action_ops act_simp_ops = {\n 208:\t\t.kind\t\t=\t\"simple\",\n 209:\t\t.id\t\t=\tTCA_ID_SIMP,\n 210:\t\t.owner\t\t=\tTHIS_MODULE,\n"
} |
| 87/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 32851 output: 31 thoughts: 107 Thoughts: **Analyzing the TCA Simplification** Okay, so `tcf_simp_dump` is dumping out the core elements: `TCA_DEF_PARMS`, `TCA_DEF_DATA` (up to a size defined by `SIMP_MAX_DATA`), and `TCA_DEF_TM`. That makes sense; it's the standard stuff needed for the definition. And I'm seeing that `tcf_simp_get_fill_size` is doing the calculation for the size needed for the Netlink message, specifically the total size for a `struct tc_defact` and then the `SIMP_MAX_DATA` element within it. So, that explains the size calculations. Now, let's switch gears and check out `act_skbmod.c` and how that interacts with the simplification. I need to see how the simplification logic is integrated into the skbmod action and see if there are any obvious issues. I expect to find some interesting interactions there, especially around how the data is handled. |
| 88/3 | 2026/09/22 05:26 | tool | grepper |
0mArgs:{
"Expression": "tcf_skbmod_dump",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_skbmod.c=231=static void tcf_skbmod_cleanup(struct tc_action *a)\n--\nnet/sched/act_skbmod.c-240-\nnet/sched/act_skbmod.c:241:static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,\nnet/sched/act_skbmod.c-242-\t\t\t int bind, int ref)\n--\nnet/sched/act_skbmod.c=290=static struct tc_action_ops act_skbmod_ops = {\n--\nnet/sched/act_skbmod.c-294-\t.act\t\t=\ttcf_skbmod_act,\nnet/sched/act_skbmod.c:295:\t.dump\t\t=\ttcf_skbmod_dump,\nnet/sched/act_skbmod.c-296-\t.get_fill_size\t=\ttcf_skbmod_get_fill_size,\n"
} |
| 89/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 33469 output: 38 thoughts: 26 Thoughts: Here's my summary, as if I were thinking these thoughts: **Diving into the `act_skbmod` Implementation** Okay, time to get my hands dirty. I'm going to take a look at the `tcf_skbmod_dump` function. I know it's located within `net/sched/act_skbmod.c`, which makes sense given this is an skbmod action. I'm especially interested in the particulars of the dump function. I'm assuming that it is used to output the current state of an `skbmod` action's configuration, likely for debugging or inspection. It's often the most critical point for debugging. I'm eager to understand how the internal state of the action is serialized into some user-readable format. |
| 90/3 | 2026/09/22 05:26 | tool | read-file |
0mArgs:{
"File": "net/sched/act_skbmod.c",
"FirstLine": 241,
"LineCount": 45
}Results: {
"Contents": " 241:\tstatic int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,\n 242:\t\t\t\t int bind, int ref)\n 243:\t{\n 244:\t\tstruct tcf_skbmod *d = to_skbmod(a);\n 245:\t\tunsigned char *b = skb_tail_pointer(skb);\n 246:\t\tstruct tcf_skbmod_params *p;\n 247:\t\tstruct tc_skbmod opt;\n 248:\t\tstruct tcf_t t;\n 249:\t\n 250:\t\tmemset(\u0026opt, 0, sizeof(opt));\n 251:\t\topt.index = d-\u003etcf_index;\n 252:\t\topt.refcnt = refcount_read(\u0026d-\u003etcf_refcnt) - ref;\n 253:\t\topt.bindcnt = atomic_read(\u0026d-\u003etcf_bindcnt) - bind;\n 254:\t\trcu_read_lock();\n 255:\t\tp = rcu_dereference(d-\u003eskbmod_p);\n 256:\t\topt.action = p-\u003eaction;\n 257:\t\topt.flags = p-\u003eflags;\n 258:\t\tif (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), \u0026opt))\n 259:\t\t\tgoto nla_put_failure;\n 260:\t\tif ((p-\u003eflags \u0026 SKBMOD_F_DMAC) \u0026\u0026\n 261:\t\t nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p-\u003eeth_dst))\n 262:\t\t\tgoto nla_put_failure;\n 263:\t\tif ((p-\u003eflags \u0026 SKBMOD_F_SMAC) \u0026\u0026\n 264:\t\t nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p-\u003eeth_src))\n 265:\t\t\tgoto nla_put_failure;\n 266:\t\tif ((p-\u003eflags \u0026 SKBMOD_F_ETYPE) \u0026\u0026\n 267:\t\t nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p-\u003eeth_type)))\n 268:\t\t\tgoto nla_put_failure;\n 269:\t\n 270:\t\ttcf_tm_dump(\u0026t, \u0026d-\u003etcf_tm);\n 271:\t\tif (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), \u0026t, TCA_SKBMOD_PAD))\n 272:\t\t\tgoto nla_put_failure;\n 273:\t\n 274:\t\trcu_read_unlock();\n 275:\t\treturn skb-\u003elen;\n 276:\tnla_put_failure:\n 277:\t\trcu_read_unlock();\n 278:\t\tnlmsg_trim(skb, b);\n 279:\t\treturn -1;\n 280:\t}\n 281:\t\n 282:\tstatic size_t tcf_skbmod_get_fill_size(const struct tc_action *act)\n 283:\t{\n 284:\t\treturn nla_total_size(sizeof(struct tc_skbmod)) /* TCA_SKBMOD_PARMS */\n 285:\t\t\t+ nla_total_size(ETH_ALEN) /* TCA_SKBMOD_DMAC */\n"
} |
| 91/3 | 2026/09/22 05:26 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 34594 output: 32 thoughts: 1314 Thoughts: **Analysis of the Traffic Control Action Module Patch** Okay, let's break this down. From what I see, we're dealing with a patch aimed at improving the reliability and completeness of Netlink notifications when adding, deleting, or retrieving Traffic Control (TC) actions. First, I'm noting that `tcf_skbmod_dump` handles the dumping of `TCA_SKBMOD_PARMS` and optional attributes like MAC addresses, EtherType, and traffic class in the `skbmod` module, while `tcf_skbmod_get_fill_size` calculates the necessary buffer size for the same. The core of this patch seems to be addressing issues related to insufficient buffer allocation for Netlink notifications. Previously, when an error message (`extack->_msg`) was present within the action notification, its size wasn't being correctly accounted for in the System sk_buff allocation, potentially leading to allocation of an inadequate buffer for the Netlink message. Furthermore, some TC action modules lacked a `get_fill_size` implementation, meaning the notification size was based on a more limited attribute set. This could result in truncation or failures (`-EINVAL`/`-ENOBUFS`) when dumping or notifying about the action, particularly if the required buffer size exceeded `NLMSG_GOODSIZE`. This commit adds `tcf_action_warn_attr_size` to calculate the size of `extack->_msg`, and includes this in `alloc_skb` within `tcf_del_notify_msg` and `tcf_add_notify_msg`. It also adds `get_fill_size` for various modules like `act_connmark`, `act_mpls`, `act_nat`, `act_simple`, and `act_skbmod`, and fixes `act_mirred` by adding missing `TCA_MIRRED_BLOCKID`. My immediate concern is always with uninitialized memory reads or information leaks. I want to be *sure* the patch doesn't introduce any vulnerabilities in this regard. So let's investigate the potential impact: 1. **Kernel Structures Sent to User Space:** I've looked at the changes in `act_api.c`, and the modules themselves. `tcf_action_warn_attr_size` computes a size calculation based on `strlen(extack->_msg) + 1` and `alloc_skb` allocates the buffer. However, none of the dump functions were touched or the structure serialization code, and they were already using zero-initialization or structure initializers. *Crucially, I see no changes to the code that actually serializes data for transmission to user space.* So, no new structures are exposed. 2. **Conditional Logic:** The new `if (unlikely(extack && extack->_msg))` check is safe. `extack` is a pointer, checked for NULL, and then its field `_msg` is checked for NULL. The `_msg` field is either NULL or a string initialized by `NL_SET_ERR_MSG`, meaning a null-terminated string, so no issues here. 3. **Complex Data Structures:** No new data structures are allocated or initialized here. Only the size of the sk_buff allocation is increased. 4. **Bounds Checks:** `alloc_skb` just allocates the buffer. Then, during the `tca_get_fill()` operation, functions like `nlmsg_put()`, `nla_put()` are called, which write initialized data. *The crucial point is that Netlink buffers only transmit up to the `skb->len` byte*, and padding is handled by `nlmsg_put`, `nla_put`, and `__nla_reserve`. Increasing the allocated buffer doesn't cause any uninitialized bytes to be sent to userspace. I'm confident that this patch increases allocation for the notification buffer. I don't see any way this leads to any uninitialized memory read or info-leak. After going over the code, the only thing that changes is that we will allocate an adequate buffer for Netlink notifications and avoid some potential failures. |
| 92/3 | 2026/09/22 05:27 | tool | grepper |
0mArgs:{
"Expression": "tcf_del_notify_msg",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=1927=int tcf_action_reoffload_cb(flow_indr_block_bind_cb_t *cb,\n--\nnet/sched/act_api.c-1984-\nnet/sched/act_api.c:1985:static struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,\nnet/sched/act_api.c-1986-\t\t\t\t\t struct tc_action *actions[],\n--\nnet/sched/act_api.c=2007=static int tcf_del_notify(struct net *net, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-2016-\t} else {\nnet/sched/act_api.c:2017:\t\tskb = tcf_del_notify_msg(net, n, actions, portid, attr_size,\nnet/sched/act_api.c-2018-\t\t\t\t\t extack);\n"
} |
| 93/3 | 2026/09/22 05:27 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 37083 output: 31 thoughts: 23 Thoughts: Here's my attempt at summarizing those thoughts, tailored for an expert audience and written in the first person: **Analyzing `tcf_del_notify` and `tcf_add_notify` Calls** Alright, let's dive into the call sites of `tcf_del_notify` and `tcf_add_notify`. I want to quickly map out where these functions are being used within the TCF framework, and understand the contexts surrounding their invocations. I'm focusing on the *how* and the *why* of the notification management. My immediate concern is the scenarios where notifications are added and removed. I need to refresh my understanding of the relationship between the notification and the data it relates to. I'm interested in the scope and implications of these calls, specifically in terms of performance and potential race conditions. I'm going to pay close attention to the data structures these notifications are interacting with. Understanding the lifetime and the purpose of the notifications is essential for ensuring robust and efficient operation. |
| 94/3 | 2026/09/22 05:27 | tool | grepper |
0mArgs:{
"Expression": "tcf_del_notify\\(",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=1985=static struct sk_buff *tcf_del_notify_msg(struct net *net, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-2006-\nnet/sched/act_api.c:2007:static int tcf_del_notify(struct net *net, struct nlmsghdr *n,\nnet/sched/act_api.c-2008-\t\t\t struct tc_action *actions[], u32 portid,\n--\nnet/sched/act_api.c=2036=tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-2073-\telse { /* delete */\nnet/sched/act_api.c:2074:\t\tret = tcf_del_notify(net, n, actions, portid, attr_size, extack);\nnet/sched/act_api.c-2075-\t\tif (ret)\n"
} |
| 95/3 | 2026/09/22 05:27 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 37623 output: 31 thoughts: 9 Thoughts: Okay, here's my interpretation of that thought process, summarized as you requested: **Navigating the `tcf_add_notify` Functionality** Alright, so I'm thinking about this `tcf_add_notify` function. It seems pretty central to how this whole notification system is built, and it's got my attention. My initial focus has to be on how it integrates with the rest of the codebase. I'm wondering: what are the specific data structures it's interacting with? Where is this function typically called from? What are the potential error conditions I need to anticipate? I need to understand what inputs it expects and what kind of output it produces. Is it returning a success/failure code? Does it modify any global state, and if so, how is that handled for thread safety or reentrancy? I'm already imagining the potential race conditions or locking issues that could arise if this isn't handled carefully. I need to dive deeper into its signature and look for any clues. I’m particularly curious about the notify *itself*. What exactly gets notified and to whom. What’s the notification mechanism? I'm hoping to get a clearer picture of whether it’s a simple callback, or if there's a more complex publish-subscribe architecture at play. That'll influence how I think about testing and debugging. I'm considering what impact changes to it would have on the system. This is fundamental, and will require a close read to see how the system is currently architected. |
| 96/3 | 2026/09/22 05:27 | tool | grepper |
0mArgs:{
"Expression": "tcf_add_notify\\(",
"PathPrefix": "net/sched/"
}Results: {
"Output": "net/sched/act_api.c=2084=static struct sk_buff *tcf_add_notify_msg(struct net *net, struct nlmsghdr *n,\n--\nnet/sched/act_api.c-2105-\nnet/sched/act_api.c:2106:static int tcf_add_notify(struct net *net, struct nlmsghdr *n,\nnet/sched/act_api.c-2107-\t\t\t struct tc_action *actions[], u32 portid,\n--\nnet/sched/act_api.c=2125=static int tcf_action_add(struct net *net, struct nlattr *nla,\n--\nnet/sched/act_api.c-2143-\nnet/sched/act_api.c:2144:\tret = tcf_add_notify(net, n, actions, portid, attr_size, extack);\nnet/sched/act_api.c-2145-\n"
} |
| 97/3 | 2026/09/22 05:27 | llm | kmsan-evaluator |
0mModel:gemini-3.8-flash Args: null Results: null Tokens: input: 38244 output: 339 thoughts: 634 Thoughts: **My Analysis of the Patch and KMSAN Requirement** Okay, so I've been looking over this patch and considering whether it warrants a KMSAN check. Let's break this down. From the code, in `rtnetlink_rcv_msg`, the `extack` structure is zero-initialized by the caller. This means that unless explicitly populated (like with `NL_SET_ERR_MSG`), the internal `_msg` pointer is initially `NULL`. The core of the change seems to be around improving how we size the skb buffer in the `tca_get_fill()` function and other similar functions within the traffic control (TC) framework. Specifically, the patch: 1. Calculates the correct size for the `extack->_msg` string when allocating the notification skb. This avoids running out of space for warning messages. 2. Provides accurate `.get_fill_size()` callbacks within different `act_*.c` modules. This ensures the skb allocated by `act_api.c` has sufficient capacity to accommodate all action-specific attributes during a dump operation. The key thing I'm seeing is that *everything* the patch touches is related to size calculations, primarily for the `alloc_skb()` function. There aren't any new uninitialized variables introduced. There are no uninitialized reads or writes introduced by this patch. And crucially, there's no data that could potentially leak uninitialized memory to user space. KASAN would definitely catch any buffer overflows or out-of-bounds access issues. Even if there were sizing errors with the `skb`, it would result in an error code, not a KMSAN-detectable leak. The purpose of KMSAN is specifically to catch the use and leakage of uninitialized memory. In my expert opinion, this patch doesn't introduce or affect anything in that regard. Given the stated requirements for a KMSAN check, the patch doesn't seem to meet the criteria. Let's double-check my reasoning against the rule. The rule says a KMSAN session is unnecessary if a bug can be caught by KASAN or another standard detector. I'm confident that KASAN would have caught any potential buffer overflow issues here. Also, the patch has no uninitialized memory risks. All of the stack/heap structures being worked with are fully initialized. Therefore, I can confidently state: * `NeedsKMSAN = false` Now, let's call `set-results` with the reasoning: I'm describing the patch as improving the skb buffer size calculation for TC action notifications. This is achieved by taking into account warning messages from `extack` and by providing `.get_fill_size` callbacks for several TC actions. The KMSAN check isn't necessary because there are no uninitialized memory accesses, no struct padding or uninitialized fields exposed to user space. Existing dump functions already correctly initialize all fields, and the changes simply adjust the capacity parameter passed to `alloc_skb()`. |
| 98/3 | 2026/09/22 05:27 | tool | set-results |
0mArgs:{
"KMSANReasoning": "The patch series improves the buffer allocation size calculations for netlink notification skbs in the TC action subsystem (net/sched). Specifically, it accounts for potential warning messages from netlink_ext_ack in tcf_action_warn_attr_size() when allocating skbs in tcf_del_notify_msg() and tcf_add_notify_msg(), and implements/corrects the .get_fill_size callback for several action modules (act_connmark, act_mirred, act_mpls, act_nat, act_simple, act_skbmod) so that the maximum size needed by their dump callbacks is pre-calculated accurately.\n\nThese changes only affect the size argument passed to alloc_skb() to prevent buffer exhaustion and message trimming during tca_get_fill(). They do not introduce, modify, or expose any uninitialized memory or info-leaks:\n1. No changes are made to how data is serialized or dumped into netlink skbs; the dump functions themselves are unchanged and already properly initialize all structs before calling nla_put().\n2. The skb buffer sizing does not affect the amount of data copied to userspace, as skb-\u003elen is determined strictly by the formatted netlink attributes.\n3. No uninitialized variables, heap allocations, or struct fields are read or branched upon.\n\nBecause there are no uninitialized memory risks or kernel-to-user info-leak risks, running a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
}Results: {
"KMSANReasoning": "The patch series improves the buffer allocation size calculations for netlink notification skbs in the TC action subsystem (net/sched). Specifically, it accounts for potential warning messages from netlink_ext_ack in tcf_action_warn_attr_size() when allocating skbs in tcf_del_notify_msg() and tcf_add_notify_msg(), and implements/corrects the .get_fill_size callback for several action modules (act_connmark, act_mirred, act_mpls, act_nat, act_simple, act_skbmod) so that the maximum size needed by their dump callbacks is pre-calculated accurately.\n\nThese changes only affect the size argument passed to alloc_skb() to prevent buffer exhaustion and message trimming during tca_get_fill(). They do not introduce, modify, or expose any uninitialized memory or info-leaks:\n1. No changes are made to how data is serialized or dumped into netlink skbs; the dump functions themselves are unchanged and already properly initialize all structs before calling nla_put().\n2. The skb buffer sizing does not affect the amount of data copied to userspace, as skb-\u003elen is determined strictly by the formatted netlink attributes.\n3. No uninitialized variables, heap allocations, or struct fields are read or branched upon.\n\nBecause there are no uninitialized memory risks or kernel-to-user info-leak risks, running a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
} |
| Total Calls | Total Tokens | Avg Tokens | Total Duration (Seconds) | Avg Duration (Seconds) |
|---|
| Total Calls | Total Duration (Seconds) | Avg Duration (Seconds) |
|---|