AI Trajectory


Trajectory: (Expand/Collapse All)
Seq Timestamp Type Name Duration
0/0 2026/10/06 16:39 flow patch-triage
3m Args: 
null

Results: 
{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "KMSANReasoning": "",
  "NeedsKMSAN": false,
  "Reasoning": "The patch series only updates the fib_table_lookup and fib6_table_lookup tracepoints to record net-\u003enet_cookie, and plumbs the existing net pointer through fib_table_lookup to pass it to the tracepoint. No control flow, logic, or kernel data structures are altered.",
  "WorthFuzzing": false
}
1/1 2026/10/06 16:39 action read-patch-diff
0m Args: 
null

Results: 
{
  "PatchDiff": "commit 11d5f150837e73bc833ef274649afc556b63c131\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Tue Oct 6 16:38:58 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/include/net/ip_fib.h b/include/net/ip_fib.h\nindex 0a35355fb0f33..fb446f01a65dc 100644\n--- a/include/net/ip_fib.h\n+++ b/include/net/ip_fib.h\n@@ -275,8 +275,9 @@ struct fib_dump_filter {\n \tstruct net_device\t*dev;\n };\n \n-int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,\n-\t\t     struct fib_result *res, int fib_flags);\n+int fib_table_lookup(struct net *net, struct fib_table *tb,\n+\t\t     const struct flowi4 *flp, struct fib_result *res,\n+\t\t     int fib_flags);\n int fib_table_insert(struct net *, struct fib_table *, struct fib_config *,\n \t\t     struct netlink_ext_ack *extack);\n int fib_table_delete(struct net *, struct fib_table *, struct fib_config *,\n@@ -323,7 +324,8 @@ static inline int fib_lookup(struct net *net, const struct flowi4 *flp,\n \n \ttb = fib_get_table(net, RT_TABLE_MAIN);\n \tif (tb)\n-\t\terr = fib_table_lookup(tb, flp, res, flags | FIB_LOOKUP_NOREF);\n+\t\terr = fib_table_lookup(net, tb, flp, res,\n+\t\t\t\t       flags | FIB_LOOKUP_NOREF);\n \n \tif (err == -EAGAIN)\n \t\terr = -ENETUNREACH;\n@@ -387,14 +389,14 @@ static inline int fib_lookup(struct net *net, struct flowi4 *flp,\n \n \ttb = rcu_dereference_rtnl(net-\u003eipv4.fib_main);\n \tif (tb)\n-\t\terr = fib_table_lookup(tb, flp, res, flags);\n+\t\terr = fib_table_lookup(net, tb, flp, res, flags);\n \n \tif (err != -EAGAIN)\n \t\tgoto out;\n \n \ttb = rcu_dereference_rtnl(net-\u003eipv4.fib_default);\n \tif (tb)\n-\t\terr = fib_table_lookup(tb, flp, res, flags);\n+\t\terr = fib_table_lookup(net, tb, flp, res, flags);\n \n \tif (err == -EAGAIN)\n \t\terr = -ENETUNREACH;\ndiff --git a/include/trace/events/fib.h b/include/trace/events/fib.h\nindex feb28b359eff2..7852e9ba38616 100644\n--- a/include/trace/events/fib.h\n+++ b/include/trace/events/fib.h\n@@ -14,10 +14,10 @@\n \n TRACE_EVENT(fib_table_lookup,\n \n-\tTP_PROTO(u32 tb_id, const struct flowi4 *flp,\n+\tTP_PROTO(const struct net *net, u32 tb_id, const struct flowi4 *flp,\n \t\t const struct fib_nh_common *nhc, int err),\n \n-\tTP_ARGS(tb_id, flp, nhc, err),\n+\tTP_ARGS(net, tb_id, flp, nhc, err),\n \n \tTP_STRUCT__entry(\n \t\t__field(\tu32,\ttb_id\t\t)\n@@ -35,6 +35,7 @@ TRACE_EVENT(fib_table_lookup,\n \t\t__field(\tu16,\tsport\t\t)\n \t\t__field(\tu16,\tdport\t\t)\n \t\t__array(char,  name,   IFNAMSIZ )\n+\t\t__field(\tu64,\tnet_cookie\t)\n \t),\n \n \tTP_fast_assign(\n@@ -90,13 +91,16 @@ TRACE_EVENT(fib_table_lookup,\n \t\t\tin6 = (struct in6_addr *)__entry-\u003egw6;\n \t\t\t*in6 = in6addr_any;\n \t\t}\n+\n+\t\t__entry-\u003enet_cookie = net-\u003enet_cookie;\n \t),\n \n-\tTP_printk(\"table %u oif %d iif %d proto %u %pI4/%u -\u003e %pI4/%u tos %d scope %d flags %x ==\u003e dev %s gw %pI4/%pI6c err %d\",\n+\tTP_printk(\"table %u oif %d iif %d proto %u %pI4/%u -\u003e %pI4/%u tos %d scope %d flags %x ==\u003e dev %s gw %pI4/%pI6c err %d net_cookie %llu\",\n \t\t  __entry-\u003etb_id, __entry-\u003eoif, __entry-\u003eiif, __entry-\u003eproto,\n \t\t  __entry-\u003esrc, __entry-\u003esport, __entry-\u003edst, __entry-\u003edport,\n \t\t  __entry-\u003etos, __entry-\u003escope, __entry-\u003eflags,\n-\t\t  __entry-\u003ename, __entry-\u003egw4, __entry-\u003egw6, __entry-\u003eerr)\n+\t\t  __entry-\u003ename, __entry-\u003egw4, __entry-\u003egw6, __entry-\u003eerr,\n+\t\t  __entry-\u003enet_cookie)\n );\n #endif /* _TRACE_FIB_H */\n \ndiff --git a/include/trace/events/fib6.h b/include/trace/events/fib6.h\nindex 8d22b2e98d481..e58facd2d7d4a 100644\n--- a/include/trace/events/fib6.h\n+++ b/include/trace/events/fib6.h\n@@ -34,6 +34,7 @@ TRACE_EVENT(fib6_table_lookup,\n \t\t__field(        u8,\trt_type\t\t)\n \t\t__array(\t\tchar,\tname,\tIFNAMSIZ )\n \t\t__array(\t\t__u8,\tgw,\t16\t )\n+\t\t__field(\tu64,\tnet_cookie\t)\n \t),\n \n \tTP_fast_assign(\n@@ -76,13 +77,16 @@ TRACE_EVENT(fib6_table_lookup,\n \t\t\tin6 = (struct in6_addr *)__entry-\u003egw;\n \t\t\t*in6 = res-\u003enh-\u003efib_nh_gw6;\n \t\t}\n+\n+\t\t__entry-\u003enet_cookie = net-\u003enet_cookie;\n \t),\n \n-\tTP_printk(\"table %3u oif %d iif %d proto %u %pI6c/%u -\u003e %pI6c/%u flowlabel %#x tos %d scope %d flags %x ==\u003e dev %s gw %pI6c err %d\",\n+\tTP_printk(\"table %3u oif %d iif %d proto %u %pI6c/%u -\u003e %pI6c/%u flowlabel %#x tos %d scope %d flags %x ==\u003e dev %s gw %pI6c err %d net_cookie %llu\",\n \t\t  __entry-\u003etb_id, __entry-\u003eoif, __entry-\u003eiif, __entry-\u003eproto,\n \t\t  __entry-\u003esrc, __entry-\u003esport, __entry-\u003edst, __entry-\u003edport,\n \t\t  __entry-\u003eflowlabel, __entry-\u003etos, __entry-\u003escope,\n-\t\t  __entry-\u003eflags, __entry-\u003ename, __entry-\u003egw, __entry-\u003eerr)\n+\t\t  __entry-\u003eflags, __entry-\u003ename, __entry-\u003egw, __entry-\u003eerr,\n+\t\t  __entry-\u003enet_cookie)\n );\n \n #endif /* _TRACE_FIB6_H */\ndiff --git a/net/core/filter.c b/net/core/filter.c\nindex 70dc621672f2e..3ee1a093337e3 100644\n--- a/net/core/filter.c\n+++ b/net/core/filter.c\n@@ -6413,7 +6413,7 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,\n \t\tif (unlikely(!tb))\n \t\t\treturn BPF_FIB_LKUP_RET_NOT_FWDED;\n \n-\t\terr = fib_table_lookup(tb, \u0026fl4, \u0026res, FIB_LOOKUP_NOREF);\n+\t\terr = fib_table_lookup(net, tb, \u0026fl4, \u0026res, FIB_LOOKUP_NOREF);\n \t} else {\n \t\tif (flags \u0026 BPF_FIB_LOOKUP_MARK)\n \t\t\tfl4.flowi4_mark = params-\u003emark;\ndiff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c\nindex e84d3cf922474..efcd9fc881391 100644\n--- a/net/ipv4/devinet.c\n+++ b/net/ipv4/devinet.c\n@@ -157,7 +157,8 @@ struct net_device *__ip_dev_find(struct net *net, __be32 addr, bool devref)\n \t\t */\n \t\tlocal = fib_get_table(net, RT_TABLE_LOCAL);\n \t\tif (local \u0026\u0026\n-\t\t    !fib_table_lookup(local, \u0026fl4, \u0026res, FIB_LOOKUP_NOREF) \u0026\u0026\n+\t\t    !fib_table_lookup(net, local, \u0026fl4, \u0026res,\n+\t\t\t\t      FIB_LOOKUP_NOREF) \u0026\u0026\n \t\t    res.type == RTN_LOCAL)\n \t\t\tresult = FIB_RES_DEV(res);\n \t} else {\ndiff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c\nindex 8a3dc04e8cac6..c80c1b36f1fd0 100644\n--- a/net/ipv4/fib_frontend.c\n+++ b/net/ipv4/fib_frontend.c\n@@ -243,7 +243,8 @@ static inline unsigned int __inet_dev_addr_type(struct net *net,\n \ttable = fib_get_table(net, tb_id);\n \tif (table) {\n \t\tret = RTN_UNICAST;\n-\t\tif (!fib_table_lookup(table, \u0026fl4, \u0026res, FIB_LOOKUP_NOREF)) {\n+\t\tif (!fib_table_lookup(net, table, \u0026fl4, \u0026res,\n+\t\t\t\t      FIB_LOOKUP_NOREF)) {\n \t\t\tstruct fib_nh_common *nhc = fib_info_nhc(res.fi, 0);\n \n \t\t\tif (!dev || dev == nhc-\u003enhc_dev)\n@@ -1400,7 +1401,8 @@ static void nl_fib_lookup(struct net *net, struct fib_result_nl *frn)\n \t\tlocal_bh_disable();\n \n \t\tfrn-\u003etb_id = tb-\u003etb_id;\n-\t\tfrn-\u003eerr = fib_table_lookup(tb, \u0026fl4, \u0026res, FIB_LOOKUP_NOREF);\n+\t\tfrn-\u003eerr = fib_table_lookup(net, tb, \u0026fl4, \u0026res,\n+\t\t\t\t\t    FIB_LOOKUP_NOREF);\n \n \t\tif (!frn-\u003eerr) {\n \t\t\tfrn-\u003eprefixlen = res.prefixlen;\ndiff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c\nindex 060501b376a85..28ba351253835 100644\n--- a/net/ipv4/fib_rules.c\n+++ b/net/ipv4/fib_rules.c\n@@ -136,7 +136,7 @@ INDIRECT_CALLABLE_SCOPE int fib4_rule_action(struct fib_rule *rule,\n \ttb_id = fib_rule_get_table(rule, arg);\n \ttbl = fib_get_table(rule-\u003efr_net, tb_id);\n \tif (tbl)\n-\t\terr = fib_table_lookup(tbl, \u0026flp-\u003eu.ip4,\n+\t\terr = fib_table_lookup(rule-\u003efr_net, tbl, \u0026flp-\u003eu.ip4,\n \t\t\t\t       (struct fib_result *)arg-\u003eresult,\n \t\t\t\t       arg-\u003eflags);\n \ndiff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c\nindex e3bcc25229b0d..f064bee79806d 100644\n--- a/net/ipv4/fib_semantics.c\n+++ b/net/ipv4/fib_semantics.c\n@@ -1222,7 +1222,7 @@ static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,\n \t\t\ttbl = fib_get_table(net, table);\n \n \t\tif (tbl)\n-\t\t\terr = fib_table_lookup(tbl, \u0026fl4, \u0026res,\n+\t\t\terr = fib_table_lookup(net, tbl, \u0026fl4, \u0026res,\n \t\t\t\t\t       FIB_LOOKUP_IGNORE_LINKSTATE |\n \t\t\t\t\t       FIB_LOOKUP_NOREF);\n \ndiff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c\nindex acb1e43859143..6ab95e19b3cf9 100644\n--- a/net/ipv4/fib_trie.c\n+++ b/net/ipv4/fib_trie.c\n@@ -1417,8 +1417,9 @@ bool fib_lookup_good_nhc(const struct fib_nh_common *nhc, int fib_flags,\n }\n \n /* should be called with rcu_read_lock */\n-int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,\n-\t\t     struct fib_result *res, int fib_flags)\n+int fib_table_lookup(struct net *net, struct fib_table *tb,\n+\t\t     const struct flowi4 *flp, struct fib_result *res,\n+\t\t     int fib_flags)\n {\n \tstruct trie *t = (struct trie *) tb-\u003etb_data;\n #ifdef CONFIG_IP_FIB_TRIE_STATS\n@@ -1435,7 +1436,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,\n \n \tn = get_child_rcu(pn, cindex);\n \tif (!n) {\n-\t\ttrace_fib_table_lookup(tb-\u003etb_id, flp, NULL, -EAGAIN);\n+\t\ttrace_fib_table_lookup(net, tb-\u003etb_id, flp, NULL, -EAGAIN);\n \t\treturn -EAGAIN;\n \t}\n \n@@ -1521,8 +1522,9 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,\n \t\t\t\t * further nodes to parse.\n \t\t\t\t */\n \t\t\t\tif (IS_TRIE(pn)) {\n-\t\t\t\t\ttrace_fib_table_lookup(tb-\u003etb_id, flp,\n-\t\t\t\t\t\t\t       NULL, -EAGAIN);\n+\t\t\t\t\ttrace_fib_table_lookup(net, tb-\u003etb_id,\n+\t\t\t\t\t\t\t       flp, NULL,\n+\t\t\t\t\t\t\t       -EAGAIN);\n \t\t\t\t\treturn -EAGAIN;\n \t\t\t\t}\n #ifdef CONFIG_IP_FIB_TRIE_STATS\n@@ -1569,7 +1571,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,\n #ifdef CONFIG_IP_FIB_TRIE_STATS\n \t\t\tthis_cpu_inc(stats-\u003esemantic_match_passed);\n #endif\n-\t\t\ttrace_fib_table_lookup(tb-\u003etb_id, flp, NULL, err);\n+\t\t\ttrace_fib_table_lookup(net, tb-\u003etb_id, flp, NULL, err);\n \t\t\treturn err;\n \t\t}\n \t\tif (fi-\u003efib_flags \u0026 RTNH_F_DEAD)\n@@ -1610,7 +1612,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,\n #ifdef CONFIG_IP_FIB_TRIE_STATS\n \t\t\tthis_cpu_inc(stats-\u003esemantic_match_passed);\n #endif\n-\t\t\ttrace_fib_table_lookup(tb-\u003etb_id, flp, nhc, err);\n+\t\t\ttrace_fib_table_lookup(net, tb-\u003etb_id, flp, nhc, err);\n \n \t\t\treturn err;\n \t\t}\n"
}
2/1 2026/10/06 16:39 agent patch-evaluator
3m Model: 
core

Args: 
null

Results: 
{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch series only updates the fib_table_lookup and fib6_table_lookup tracepoints to record net-\u003enet_cookie, and plumbs the existing net pointer through fib_table_lookup to pass it to the tracepoint. No control flow, logic, or kernel data structures are altered.",
  "WorthFuzzing": false
}

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 11d5f150837e73bc833ef274649afc556b63c131
Author: syz-cluster <triage@syzkaller.com>
Date:   Tue Oct 6 16:38:58 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 0a35355fb0f33..fb446f01a65dc 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -275,8 +275,9 @@ struct fib_dump_filter {
 	struct net_device	*dev;
 };
 
-int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
-		     struct fib_result *res, int fib_flags);
+int fib_table_lookup(struct net *net, struct fib_table *tb,
+		     const struct flowi4 *flp, struct fib_result *res,
+		     int fib_flags);
 int fib_table_insert(struct net *, struct fib_table *, struct fib_config *,
 		     struct netlink_ext_ack *extack);
 int fib_table_delete(struct net *, struct fib_table *, struct fib_config *,
@@ -323,7 +324,8 @@ static inline int fib_lookup(struct net *net, const struct flowi4 *flp,
 
 	tb = fib_get_table(net, RT_TABLE_MAIN);
 	if (tb)
-		err = fib_table_lookup(tb, flp, res, flags | FIB_LOOKUP_NOREF);
+		err = fib_table_lookup(net, tb, flp, res,
+				       flags | FIB_LOOKUP_NOREF);
 
 	if (err == -EAGAIN)
 		err = -ENETUNREACH;
@@ -387,14 +389,14 @@ static inline int fib_lookup(struct net *net, struct flowi4 *flp,
 
 	tb = rcu_dereference_rtnl(net->ipv4.fib_main);
 	if (tb)
-		err = fib_table_lookup(tb, flp, res, flags);
+		err = fib_table_lookup(net, tb, flp, res, flags);
 
 	if (err != -EAGAIN)
 		goto out;
 
 	tb = rcu_dereference_rtnl(net->ipv4.fib_default);
 	if (tb)
-		err = fib_table_lookup(tb, flp, res, flags);
+		err = fib_table_lookup(net, tb, flp, res, flags);
 
 	if (err == -EAGAIN)
 		err = -ENETUNREACH;
diff --git a/include/trace/events/fib.h b/include/trace/events/fib.h
index feb28b359eff2..7852e9ba38616 100644
--- a/include/trace/events/fib.h
+++ b/include/trace/events/fib.h
@@ -14,10 +14,10 @@
 
 TRACE_EVENT(fib_table_lookup,
 
-	TP_PROTO(u32 tb_id, const struct flowi4 *flp,
+	TP_PROTO(const struct net *net, u32 tb_id, const struct flowi4 *flp,
 		 const struct fib_nh_common *nhc, int err),
 
-	TP_ARGS(tb_id, flp, nhc, err),
+	TP_ARGS(net, tb_id, flp, nhc, err),
 
 	TP_STRUCT__entry(
 		__field(	u32,	tb_id		)
@@ -35,6 +35,7 @@ TRACE_EVENT(fib_table_lookup,
 		__field(	u16,	sport		)
 		__field(	u16,	dport		)
 		__array(char,  name,   IFNAMSIZ )
+		__field(	u64,	net_cookie	)
 	),
 
 	TP_fast_assign(
@@ -90,13 +91,16 @@ TRACE_EVENT(fib_table_lookup,
 			in6 = (struct in6_addr *)__entry->gw6;
 			*in6 = in6addr_any;
 		}
+
+		__entry->net_cookie = net->net_cookie;
 	),
 
-	TP_printk("table %u oif %d iif %d proto %u %pI4/%u -> %pI4/%u tos %d scope %d flags %x ==> dev %s gw %pI4/%pI6c err %d",
+	TP_printk("table %u oif %d iif %d proto %u %pI4/%u -> %pI4/%u tos %d scope %d flags %x ==> dev %s gw %pI4/%pI6c err %d net_cookie %llu",
 		  __entry->tb_id, __entry->oif, __entry->iif, __entry->proto,
 		  __entry->src, __entry->sport, __entry->dst, __entry->dport,
 		  __entry->tos, __entry->scope, __entry->flags,
-		  __entry->name, __entry->gw4, __entry->gw6, __entry->err)
+		  __entry->name, __entry->gw4, __entry->gw6, __entry->err,
+		  __entry->net_cookie)
 );
 #endif /* _TRACE_FIB_H */
 
diff --git a/include/trace/events/fib6.h b/include/trace/events/fib6.h
index 8d22b2e98d481..e58facd2d7d4a 100644
--- a/include/trace/events/fib6.h
+++ b/include/trace/events/fib6.h
@@ -34,6 +34,7 @@ TRACE_EVENT(fib6_table_lookup,
 		__field(        u8,	rt_type		)
 		__array(		char,	name,	IFNAMSIZ )
 		__array(		__u8,	gw,	16	 )
+		__field(	u64,	net_cookie	)
 	),
 
 	TP_fast_assign(
@@ -76,13 +77,16 @@ TRACE_EVENT(fib6_table_lookup,
 			in6 = (struct in6_addr *)__entry->gw;
 			*in6 = res->nh->fib_nh_gw6;
 		}
+
+		__entry->net_cookie = net->net_cookie;
 	),
 
-	TP_printk("table %3u oif %d iif %d proto %u %pI6c/%u -> %pI6c/%u flowlabel %#x tos %d scope %d flags %x ==> dev %s gw %pI6c err %d",
+	TP_printk("table %3u oif %d iif %d proto %u %pI6c/%u -> %pI6c/%u flowlabel %#x tos %d scope %d flags %x ==> dev %s gw %pI6c err %d net_cookie %llu",
 		  __entry->tb_id, __entry->oif, __entry->iif, __entry->proto,
 		  __entry->src, __entry->sport, __entry->dst, __entry->dport,
 		  __entry->flowlabel, __entry->tos, __entry->scope,
-		  __entry->flags, __entry->name, __entry->gw, __entry->err)
+		  __entry->flags, __entry->name, __entry->gw, __entry->err,
+		  __entry->net_cookie)
 );
 
 #endif /* _TRACE_FIB6_H */
diff --git a/net/core/filter.c b/net/core/filter.c
index 70dc621672f2e..3ee1a093337e3 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6413,7 +6413,7 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
 		if (unlikely(!tb))
 			return BPF_FIB_LKUP_RET_NOT_FWDED;
 
-		err = fib_table_lookup(tb, &fl4, &res, FIB_LOOKUP_NOREF);
+		err = fib_table_lookup(net, tb, &fl4, &res, FIB_LOOKUP_NOREF);
 	} else {
 		if (flags & BPF_FIB_LOOKUP_MARK)
 			fl4.flowi4_mark = params->mark;
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index e84d3cf922474..efcd9fc881391 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -157,7 +157,8 @@ struct net_device *__ip_dev_find(struct net *net, __be32 addr, bool devref)
 		 */
 		local = fib_get_table(net, RT_TABLE_LOCAL);
 		if (local &&
-		    !fib_table_lookup(local, &fl4, &res, FIB_LOOKUP_NOREF) &&
+		    !fib_table_lookup(net, local, &fl4, &res,
+				      FIB_LOOKUP_NOREF) &&
 		    res.type == RTN_LOCAL)
 			result = FIB_RES_DEV(res);
 	} else {
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 8a3dc04e8cac6..c80c1b36f1fd0 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -243,7 +243,8 @@ static inline unsigned int __inet_dev_addr_type(struct net *net,
 	table = fib_get_table(net, tb_id);
 	if (table) {
 		ret = RTN_UNICAST;
-		if (!fib_table_lookup(table, &fl4, &res, FIB_LOOKUP_NOREF)) {
+		if (!fib_table_lookup(net, table, &fl4, &res,
+				      FIB_LOOKUP_NOREF)) {
 			struct fib_nh_common *nhc = fib_info_nhc(res.fi, 0);
 
 			if (!dev || dev == nhc->nhc_dev)
@@ -1400,7 +1401,8 @@ static void nl_fib_lookup(struct net *net, struct fib_result_nl *frn)
 		local_bh_disable();
 
 		frn->tb_id = tb->tb_id;
-		frn->err = fib_table_lookup(tb, &fl4, &res, FIB_LOOKUP_NOREF);
+		frn->err = fib_table_lookup(net, tb, &fl4, &res,
+					    FIB_LOOKUP_NOREF);
 
 		if (!frn->err) {
 			frn->prefixlen = res.prefixlen;
diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index 060501b376a85..28ba351253835 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -136,7 +136,7 @@ INDIRECT_CALLABLE_SCOPE int fib4_rule_action(struct fib_rule *rule,
 	tb_id = fib_rule_get_table(rule, arg);
 	tbl = fib_get_table(rule->fr_net, tb_id);
 	if (tbl)
-		err = fib_table_lookup(tbl, &flp->u.ip4,
+		err = fib_table_lookup(rule->fr_net, tbl, &flp->u.ip4,
 				       (struct fib_result *)arg->result,
 				       arg->flags);
 
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index e3bcc25229b0d..f064bee79806d 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1222,7 +1222,7 @@ static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
 			tbl = fib_get_table(net, table);
 
 		if (tbl)
-			err = fib_table_lookup(tbl, &fl4, &res,
+			err = fib_table_lookup(net, tbl, &fl4, &res,
 					       FIB_LOOKUP_IGNORE_LINKSTATE |
 					       FIB_LOOKUP_NOREF);
 
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index acb1e43859143..6ab95e19b3cf9 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1417,8 +1417,9 @@ bool fib_lookup_good_nhc(const struct fib_nh_common *nhc, int fib_flags,
 }
 
 /* should be called with rcu_read_lock */
-int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
-		     struct fib_result *res, int fib_flags)
+int fib_table_lookup(struct net *net, struct fib_table *tb,
+		     const struct flowi4 *flp, struct fib_result *res,
+		     int fib_flags)
 {
 	struct trie *t = (struct trie *) tb->tb_data;
 #ifdef CONFIG_IP_FIB_TRIE_STATS
@@ -1435,7 +1436,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
 
 	n = get_child_rcu(pn, cindex);
 	if (!n) {
-		trace_fib_table_lookup(tb->tb_id, flp, NULL, -EAGAIN);
+		trace_fib_table_lookup(net, tb->tb_id, flp, NULL, -EAGAIN);
 		return -EAGAIN;
 	}
 
@@ -1521,8 +1522,9 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
 				 * further nodes to parse.
 				 */
 				if (IS_TRIE(pn)) {
-					trace_fib_table_lookup(tb->tb_id, flp,
-							       NULL, -EAGAIN);
+					trace_fib_table_lookup(net, tb->tb_id,
+							       flp, NULL,
+							       -EAGAIN);
 					return -EAGAIN;
 				}
 #ifdef CONFIG_IP_FIB_TRIE_STATS
@@ -1569,7 +1571,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
 #ifdef CONFIG_IP_FIB_TRIE_STATS
 			this_cpu_inc(stats->semantic_match_passed);
 #endif
-			trace_fib_table_lookup(tb->tb_id, flp, NULL, err);
+			trace_fib_table_lookup(net, tb->tb_id, flp, NULL, err);
 			return err;
 		}
 		if (fi->fib_flags & RTNH_F_DEAD)
@@ -1610,7 +1612,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
 #ifdef CONFIG_IP_FIB_TRIE_STATS
 			this_cpu_inc(stats->semantic_match_passed);
 #endif
-			trace_fib_table_lookup(tb->tb_id, flp, nhc, err);
+			trace_fib_table_lookup(net, tb->tb_id, flp, nhc, err);
 
 			return err;
 		}

3/2 2026/10/06 16:39 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 7035
							output: 34
							thoughts: 610

Thoughts: 
**Analyzing the FIB Table Lookup Patch**

Okay, let's dive into this patch. My initial impression is that it's introducing a significant change, likely related to network namespace awareness within the FIB (Forwarding Information Base) lookup functionality.

First, I need to understand the scope of the change. `git diff` shows the core modification: the `fib_table_lookup` function signature in `include/net/ip_fib.h` is being updated to accept a `struct net *net` argument. This is the key. Everywhere `fib_table_lookup` is called now needs to be adapted to pass this `net` pointer, which represents the network namespace.

I see that the calls to `fib_lookup()` are now correctly updated to call the new `fib_table_lookup()` with the net pointer.

The trace events in `include/trace/events/fib.h` and `include/trace/events/fib6.h` are also being adjusted to log the `net_cookie`. This strongly suggests that we're tracking the network namespace within the tracing data.

Now I'm looking at where `fib_table_lookup` is *used*. The patch updates calls to `fib_table_lookup` in `net/core/filter.c`, `net/ipv4/devinet.c`, `net/ipv4/fib_frontend.c`, `net/ipv4/fib_rules.c`, `net/ipv4/fib_semantics.c`, and `net/ipv4/fib_trie.c`. This is a pretty widespread change, hitting core IPv4 routing components.

Specifically, `net/core/filter.c` (BPF filter) is updated, `net/ipv4/devinet.c` (device address handling) is updated, and `net/ipv4/fib_rules.c` uses a pointer `rule->fr_net` to determine the netns. In `net/ipv4/fib_trie.c`, I see a call to trace `trace_fib_table_lookup()` to log the `net` and table ID.

My assumption is that the `net` pointer is being added to support network namespace isolation, which makes sense for modern networking environments.

Before making any definitive conclusions, I want to confirm that this is a single commit, or a part of a wider effort. A quick check of `git log` or `git diff` should clear that up. I need the full picture. Let me use `grepper` or check the git history to see the bigger context of this change.

4/2 2026/10/06 16:39 tool grepper
0m Args: 
{
  "Expression": "trace_fib6_table_lookup",
  "PathPrefixes": [
    "net/ipv6/"
  ]
}

Results: 
{
  "Output": "net/ipv6/route.c=1257=INDIRECT_CALLABLE_SCOPE struct rt6_info *ip6_pol_route_lookup(struct net *net,\n--\nnet/ipv6/route.c-1302-out:\nnet/ipv6/route.c:1303:\ttrace_fib6_table_lookup(net, \u0026res, table, fl6);\nnet/ipv6/route.c-1304-\n--\nnet/ipv6/route.c=2207=int fib6_table_lookup(struct net *net, struct fib6_table *table, int oif,\n--\nnet/ipv6/route.c-2228-\nnet/ipv6/route.c:2229:\ttrace_fib6_table_lookup(net, res, table, fl6);\nnet/ipv6/route.c-2230-\n--\nnet/ipv6/route.c=3080=INDIRECT_CALLABLE_SCOPE struct rt6_info *__ip6_route_redirect(struct net *net,\n--\nnet/ipv6/route.c-3158-\nnet/ipv6/route.c:3159:\ttrace_fib6_table_lookup(net, \u0026res, table, fl6);\nnet/ipv6/route.c-3160-\treturn ret;\n"
}
5/2 2026/10/06 16:39 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 8577
							output: 39
							thoughts: 50

Thoughts: 
Okay, here's my take on those thoughts, framed as an expert's internal monologue:

**IPv6 FIB Tracepoint Inspection**

Alright, let's dive into this IPv6 FIB lookup process. First instinct is to leverage existing tracepoints, so I'll check out the `trace_fib6_table_lookup` function in `net/ipv6/route.c`. Ah, perfect! It already takes the `net` namespace as its primary argument. That's exactly what I need to establish context. Saves me a headache. Now, to be sure I'm capturing everything I need, I'll move over to `include/trace/events/fib6.h`. I want to see what data is actually being traced there. This header should give me a clear picture of the event structure and the available fields I can use. This will inform my data parsing strategies going forward.

6/2 2026/10/06 16:39 tool grepper
0m Args: 
{
  "Expression": "TP_PROTO.*net.*fib6",
  "PathPrefixes": [
    "include/trace/events/fib6.h"
  ]
}

Results: 
{
  "Output": "include/trace/events/fib6.h=13=TRACE_EVENT(fib6_table_lookup,\ninclude/trace/events/fib6.h-14-\ninclude/trace/events/fib6.h:15:\tTP_PROTO(const struct net *net, const struct fib6_result *res,\ninclude/trace/events/fib6.h-16-\t\t struct fib6_table *table, const struct flowi6 *flp),\n"
}
7/2 2026/10/06 16:39 llm patch-evaluator
1m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 8976
							output: 40
							thoughts: 1016

Thoughts: 
**Analyzing the Patch for WorthFuzzing Criteria**

Okay, so initially I was thinking this was a straightforward fix: `TP_PROTO` for `fib6_table_lookup` was already taking `const struct net *net`, but it wasn't recording `net_cookie`. Then, `fib_table_lookup` *didn't* have `struct net *net`, so I added it and passed it to `trace_fib_table_lookup` to record `net_cookie`. Seemed like a useful addition, right?

But *wait a minute*. I need to carefully review the instructions on when to set `WorthFuzzing=false`. The negative criteria section is crucial. Specifically, the "Purely decorative logging... or tracepoints that do not alter control flow or data structures" part.

Is this patch *just* about adding tracepoints and plumbing a parameter? Let's re-read *very* carefully and go over the changes, line by line, to be certain:

1.  `include/net/ip_fib.h`: Added `struct net *net` as a parameter to `fib_table_lookup`. The calls to `fib_table_lookup` are updated to pass `net`.

2.  `include/trace/events/fib.h`: Added `const struct net *net` to `TP_PROTO` and now records `net->net_cookie`. Also, updated `TP_printk` to include `net_cookie`.

3.  `include/trace/events/fib6.h`: Now records `net->net_cookie` and updated `TP_printk` to include `net_cookie`.

4.  `net/core/filter.c`, `net/ipv4/devinet.c`, `net/ipv4/fib_frontend.c`, `net/ipv4/fib_rules.c`, `net/ipv4/fib_semantics.c`: Changed to call `fib_table_lookup` with the `net` parameter.

5.  `net/ipv4/fib_trie.c`: Now calls `trace_fib_table_lookup` with the `net` parameter. *Crucially*, does `fib_table_lookup` itself use `net` for *anything* other than passing it to `trace_fib_table_lookup`? I need to check the code itself!

I need to confirm that `net/ipv4/fib_trie.c` *only* uses the `net` parameter for the tracepoint. If it doesn't, this falls under the negative criteria. Time to double-check the actual source code.

8/2 2026/10/06 16:40 tool read-file
0m Args: 
{
  "File": "net/ipv4/fib_trie.c",
  "FirstLine": 1417,
  "LineCount": 60
}

Results: 
{
  "Contents": "1417:\t}\n1418:\t\n1419:\t/* should be called with rcu_read_lock */\n1420:\tint fib_table_lookup(struct net *net, struct fib_table *tb,\n1421:\t\t\t     const struct flowi4 *flp, struct fib_result *res,\n1422:\t\t\t     int fib_flags)\n1423:\t{\n1424:\t\tstruct trie *t = (struct trie *) tb-\u003etb_data;\n1425:\t#ifdef CONFIG_IP_FIB_TRIE_STATS\n1426:\t\tstruct trie_use_stats __percpu *stats = t-\u003estats;\n1427:\t#endif\n1428:\t\tconst t_key key = ntohl(flp-\u003edaddr);\n1429:\t\tstruct key_vector *n, *pn;\n1430:\t\tstruct fib_alias *fa;\n1431:\t\tunsigned long index;\n1432:\t\tt_key cindex;\n1433:\t\n1434:\t\tpn = t-\u003ekv;\n1435:\t\tcindex = 0;\n1436:\t\n1437:\t\tn = get_child_rcu(pn, cindex);\n1438:\t\tif (!n) {\n1439:\t\t\ttrace_fib_table_lookup(net, tb-\u003etb_id, flp, NULL, -EAGAIN);\n1440:\t\t\treturn -EAGAIN;\n1441:\t\t}\n1442:\t\n1443:\t#ifdef CONFIG_IP_FIB_TRIE_STATS\n1444:\t\tthis_cpu_inc(stats-\u003egets);\n1445:\t#endif\n1446:\t\n1447:\t\t/* Step 1: Travel to the longest prefix match in the trie */\n1448:\t\tfor (;;) {\n1449:\t\t\tindex = get_cindex(key, n);\n1450:\t\n1451:\t\t\t/* This bit of code is a bit tricky but it combines multiple\n1452:\t\t\t * checks into a single check.  The prefix consists of the\n1453:\t\t\t * prefix plus zeros for the \"bits\" in the prefix. The index\n1454:\t\t\t * is the difference between the key and this value.  From\n1455:\t\t\t * this we can actually derive several pieces of data.\n1456:\t\t\t *   if (index \u003e= (1ul \u003c\u003c bits))\n1457:\t\t\t *     we have a mismatch in skip bits and failed\n1458:\t\t\t *   else\n1459:\t\t\t *     we know the value is cindex\n1460:\t\t\t *\n1461:\t\t\t * This check is safe even if bits == KEYLENGTH due to the\n1462:\t\t\t * fact that we can only allocate a node with 32 bits if a\n1463:\t\t\t * long is greater than 32 bits.\n1464:\t\t\t */\n1465:\t\t\tif (index \u003e= (1ul \u003c\u003c n-\u003ebits))\n1466:\t\t\t\tbreak;\n1467:\t\n1468:\t\t\t/* we have found a leaf. Prefixes have already been compared */\n1469:\t\t\tif (IS_LEAF(n))\n1470:\t\t\t\tgoto found;\n1471:\t\n1472:\t\t\t/* only record pn and cindex if we are going to be chopping\n1473:\t\t\t * bits later.  Otherwise we are just wasting cycles.\n1474:\t\t\t */\n1475:\t\t\tif (n-\u003eslen \u003e n-\u003epos) {\n1476:\t\t\t\tpn = n;\n"
}
9/2 2026/10/06 16:40 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 11524
							output: 41
							thoughts: 28

Thoughts: 
Here's a summary of my thought process, as requested:

**Diving Deeper into `fib_table_lookup`**

Okay, so I need to understand this `fib_table_lookup` function in `net/ipv4/fib_trie.c` a bit better. My initial analysis is a good starting point, but I need to be more thorough. Let's not just skim the function definition. Let's really look at the *rest* of the code within that function. I need to understand the control flow, any helper function calls, and error handling. I want to see what assumptions it makes, and how it interacts with the trie structure. Are there any potential edge cases I should be aware of, perhaps related to different address families or FIB table configurations? I'll pay close attention to the memory access patterns, especially regarding any locking or atomic operations, if there are any, and consider potential race conditions. I want a complete picture of its behavior. Let's get to it.

10/2 2026/10/06 16:40 tool read-file
0m Args: 
{
  "File": "net/ipv4/fib_trie.c",
  "FirstLine": 1477,
  "LineCount": 100
}

Results: 
{
  "Contents": "1477:\t\t\t\tcindex = index;\n1478:\t\t\t}\n1479:\t\n1480:\t\t\tn = get_child_rcu(n, index);\n1481:\t\t\tif (unlikely(!n))\n1482:\t\t\t\tgoto backtrace;\n1483:\t\t}\n1484:\t\n1485:\t\t/* Step 2: Sort out leaves and begin backtracing for longest prefix */\n1486:\t\tfor (;;) {\n1487:\t\t\t/* record the pointer where our next node pointer is stored */\n1488:\t\t\tstruct key_vector __rcu **cptr = n-\u003etnode;\n1489:\t\n1490:\t\t\t/* This test verifies that none of the bits that differ\n1491:\t\t\t * between the key and the prefix exist in the region of\n1492:\t\t\t * the lsb and higher in the prefix.\n1493:\t\t\t */\n1494:\t\t\tif (unlikely(prefix_mismatch(key, n)) || (n-\u003eslen == n-\u003epos))\n1495:\t\t\t\tgoto backtrace;\n1496:\t\n1497:\t\t\t/* exit out and process leaf */\n1498:\t\t\tif (unlikely(IS_LEAF(n)))\n1499:\t\t\t\tbreak;\n1500:\t\n1501:\t\t\t/* Don't bother recording parent info.  Since we are in\n1502:\t\t\t * prefix match mode we will have to come back to wherever\n1503:\t\t\t * we started this traversal anyway\n1504:\t\t\t */\n1505:\t\n1506:\t\t\twhile ((n = rcu_dereference(*cptr)) == NULL) {\n1507:\tbacktrace:\n1508:\t#ifdef CONFIG_IP_FIB_TRIE_STATS\n1509:\t\t\t\tif (!n)\n1510:\t\t\t\t\tthis_cpu_inc(stats-\u003enull_node_hit);\n1511:\t#endif\n1512:\t\t\t\t/* If we are at cindex 0 there are no more bits for\n1513:\t\t\t\t * us to strip at this level so we must ascend back\n1514:\t\t\t\t * up one level to see if there are any more bits to\n1515:\t\t\t\t * be stripped there.\n1516:\t\t\t\t */\n1517:\t\t\t\twhile (!cindex) {\n1518:\t\t\t\t\tt_key pkey = pn-\u003ekey;\n1519:\t\n1520:\t\t\t\t\t/* If we don't have a parent then there is\n1521:\t\t\t\t\t * nothing for us to do as we do not have any\n1522:\t\t\t\t\t * further nodes to parse.\n1523:\t\t\t\t\t */\n1524:\t\t\t\t\tif (IS_TRIE(pn)) {\n1525:\t\t\t\t\t\ttrace_fib_table_lookup(net, tb-\u003etb_id,\n1526:\t\t\t\t\t\t\t\t       flp, NULL,\n1527:\t\t\t\t\t\t\t\t       -EAGAIN);\n1528:\t\t\t\t\t\treturn -EAGAIN;\n1529:\t\t\t\t\t}\n1530:\t#ifdef CONFIG_IP_FIB_TRIE_STATS\n1531:\t\t\t\t\tthis_cpu_inc(stats-\u003ebacktrack);\n1532:\t#endif\n1533:\t\t\t\t\t/* Get Child's index */\n1534:\t\t\t\t\tpn = node_parent_rcu(pn);\n1535:\t\t\t\t\tcindex = get_index(pkey, pn);\n1536:\t\t\t\t}\n1537:\t\n1538:\t\t\t\t/* strip the least significant bit from the cindex */\n1539:\t\t\t\tcindex \u0026= cindex - 1;\n1540:\t\n1541:\t\t\t\t/* grab pointer for next child node */\n1542:\t\t\t\tcptr = \u0026pn-\u003etnode[cindex];\n1543:\t\t\t}\n1544:\t\t}\n1545:\t\n1546:\tfound:\n1547:\t\t/* this line carries forward the xor from earlier in the function */\n1548:\t\tindex = key ^ n-\u003ekey;\n1549:\t\n1550:\t\t/* Step 3: Process the leaf, if that fails fall back to backtracing */\n1551:\t\thlist_for_each_entry_rcu(fa, \u0026n-\u003eleaf, fa_list) {\n1552:\t\t\tstruct fib_info *fi = fa-\u003efa_info;\n1553:\t\t\tstruct fib_nh_common *nhc;\n1554:\t\t\tint nhsel, err;\n1555:\t\n1556:\t\t\tif ((BITS_PER_LONG \u003e KEYLENGTH) || (fa-\u003efa_slen \u003c KEYLENGTH)) {\n1557:\t\t\t\tif (index \u003e= (1ul \u003c\u003c fa-\u003efa_slen))\n1558:\t\t\t\t\tcontinue;\n1559:\t\t\t}\n1560:\t\t\tif (fa-\u003efa_dscp \u0026\u0026 !fib_dscp_masked_match(fa-\u003efa_dscp, flp))\n1561:\t\t\t\tcontinue;\n1562:\t\t\t/* Paired with WRITE_ONCE() in fib_release_info() */\n1563:\t\t\tif (READ_ONCE(fi-\u003efib_dead))\n1564:\t\t\t\tcontinue;\n1565:\t\t\tif (fa-\u003efa_info-\u003efib_scope \u003c flp-\u003eflowi4_scope)\n1566:\t\t\t\tcontinue;\n1567:\t\t\tfib_alias_accessed(fa);\n1568:\t\t\terr = fib_props[fa-\u003efa_type].error;\n1569:\t\t\tif (unlikely(err \u003c 0)) {\n1570:\tout_reject:\n1571:\t#ifdef CONFIG_IP_FIB_TRIE_STATS\n1572:\t\t\t\tthis_cpu_inc(stats-\u003esemantic_match_passed);\n1573:\t#endif\n1574:\t\t\t\ttrace_fib_table_lookup(net, tb-\u003etb_id, flp, NULL, err);\n1575:\t\t\t\treturn err;\n1576:\t\t\t}\n"
}
11/2 2026/10/06 16:40 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 13321
							output: 40
							thoughts: 17

Thoughts: 
Okay, here's the summary, rendered as if I am the one thinking these thoughts:

**Analyzing a Specific Code Block**

Alright, I need to focus in on a particular section of this code, lines 1577 through 1625. Let me pull that block up... Okay, I've got it. Now, what's happening here? I need to quickly identify the key variables being manipulated and the core logic being implemented. I'm looking for any obvious algorithmic inefficiencies or potential areas for bugs, especially race conditions or off-by-one errors. The code style itself might provide clues - inconsistent indentation or poor commenting is always a red flag. I'm also going to check for any dependencies on other functions or modules within this block and how they relate to other parts of the codebase. Given the size of the block, I suspect there's a specific function or process being carried out here so the intention needs to be clear immediately. Based on the variable names, it looks like this section is... *[continue as if the user input includes more text]*

12/2 2026/10/06 16:40 tool read-file
0m Args: 
{
  "File": "net/ipv4/fib_trie.c",
  "FirstLine": 1577,
  "LineCount": 60
}

Results: 
{
  "Contents": "1577:\t\t\tif (fi-\u003efib_flags \u0026 RTNH_F_DEAD)\n1578:\t\t\t\tcontinue;\n1579:\t\n1580:\t\t\tif (unlikely(fi-\u003enh)) {\n1581:\t\t\t\tif (nexthop_is_blackhole(fi-\u003enh)) {\n1582:\t\t\t\t\terr = fib_props[RTN_BLACKHOLE].error;\n1583:\t\t\t\t\tgoto out_reject;\n1584:\t\t\t\t}\n1585:\t\n1586:\t\t\t\tnhc = nexthop_get_nhc_lookup(fi-\u003enh, fib_flags, flp,\n1587:\t\t\t\t\t\t\t     \u0026nhsel);\n1588:\t\t\t\tif (nhc)\n1589:\t\t\t\t\tgoto set_result;\n1590:\t\t\t\tgoto miss;\n1591:\t\t\t}\n1592:\t\n1593:\t\t\tfor (nhsel = 0; nhsel \u003c fib_info_num_path(fi); nhsel++) {\n1594:\t\t\t\tnhc = fib_info_nhc(fi, nhsel);\n1595:\t\n1596:\t\t\t\tif (!fib_lookup_good_nhc(nhc, fib_flags, flp))\n1597:\t\t\t\t\tcontinue;\n1598:\tset_result:\n1599:\t\t\t\tif (!(fib_flags \u0026 FIB_LOOKUP_NOREF))\n1600:\t\t\t\t\trefcount_inc(\u0026fi-\u003efib_clntref);\n1601:\t\n1602:\t\t\t\tres-\u003eprefix = htonl(n-\u003ekey);\n1603:\t\t\t\tres-\u003eprefixlen = KEYLENGTH - fa-\u003efa_slen;\n1604:\t\t\t\tres-\u003enh_sel = nhsel;\n1605:\t\t\t\tres-\u003enhc = nhc;\n1606:\t\t\t\tres-\u003etype = fa-\u003efa_type;\n1607:\t\t\t\tres-\u003escope = fi-\u003efib_scope;\n1608:\t\t\t\tres-\u003edscp = fa-\u003efa_dscp;\n1609:\t\t\t\tres-\u003efi = fi;\n1610:\t\t\t\tres-\u003etable = tb;\n1611:\t\t\t\tres-\u003efa_head = \u0026n-\u003eleaf;\n1612:\t#ifdef CONFIG_IP_FIB_TRIE_STATS\n1613:\t\t\t\tthis_cpu_inc(stats-\u003esemantic_match_passed);\n1614:\t#endif\n1615:\t\t\t\ttrace_fib_table_lookup(net, tb-\u003etb_id, flp, nhc, err);\n1616:\t\n1617:\t\t\t\treturn err;\n1618:\t\t\t}\n1619:\t\t}\n1620:\tmiss:\n1621:\t#ifdef CONFIG_IP_FIB_TRIE_STATS\n1622:\t\tthis_cpu_inc(stats-\u003esemantic_match_miss);\n1623:\t#endif\n1624:\t\tgoto backtrace;\n1625:\t}\n1626:\tEXPORT_SYMBOL_GPL(fib_table_lookup);\n1627:\t\n1628:\tstatic void fib_remove_alias(struct trie *t, struct key_vector *tp,\n1629:\t\t\t\t     struct key_vector *l, struct fib_alias *old)\n1630:\t{\n1631:\t\t/* record the location of the previous list_info entry */\n1632:\t\tstruct hlist_node **pprev = old-\u003efa_list.pprev;\n1633:\t\tstruct fib_alias *fa = hlist_entry(pprev, typeof(*fa), fa_list.next);\n1634:\t\n1635:\t\t/* remove the fib_alias from the list */\n1636:\t\thlist_del_rcu(\u0026old-\u003efa_list);\n"
}
13/2 2026/10/06 16:40 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 14560
							output: 33
							thoughts: 1592

Thoughts: 
**Analysis of Potential Fuzzing Worthiness**

Okay, so I'm looking at this patch and my initial thought is, "This looks like a simple tracing addition." The function `fib_table_lookup` now takes `net` and just passes it to `trace_fib_table_lookup`.  I'm trying to determine if this change warrants fuzzing.  My immediate reaction is to check the commit message or git log, but since I don't have those tools handy, I'll analyze the diff itself.

The diff shows changes in `include/net/ip_fib.h`, `include/trace/events/fib.h`, `include/trace/events/fib6.h`, and a few other locations in `net/ipv4` and `net/core`. I recall the fuzzing guidelines and focus on Section 2:  "WHEN TO RETURN WorthFuzzing=false." I'm looking for *negative* criteria – reasons *not* to fuzz.

The key line that jumps out is: "Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints that do not alter control flow or data structures."

Now, let's break this down. Is this tracepoint addition *purely* decorative? Does it alter control flow or data structures?

1.  **Tracepoints:** The patch adds `__field(u64, net_cookie)` to the `fib_table_lookup` and `fib6_table_lookup` tracepoints, logging this new field.
2.  **Function Signature:** `fib_table_lookup`'s signature changes to include `struct net *net`. All existing callers of `fib_table_lookup` already have access to the `net` pointer and simply pass it along.  I'm now thinking about the implications of adding `struct net *net` parameter to `fib_table_lookup()`.

*   `fib_lookup` (in `ip_fib.h`):  `net` is already available and passed.
*   `bpf_ipv4_fib_lookup` (in `filter.c`): `net` is available and passed.
*   `__ip_dev_find` (in `devinet.c`): `net` is available and passed.
*   `__inet_dev_addr_type` and `nl_fib_lookup` (in `fib_frontend.c`): `net` is available and passed.
*   `fib4_rule_action` (in `fib_rules.c`):  Uses `rule->fr_net`.
*   `fib_check_nh_v4_gw` (in `fib_semantics.c`): `net` is available and passed.
*   `fib_table_lookup` (in `fib_trie.c`): `net` is available and passed.

Crucially, **no other code is being touched beyond passing the net pointer to the tracepoint**.  No data structures are being modified *except* for the `TRACE_EVENT` structs themselves (which are internal). There's no change in logic, branching, return values, loop conditions, or state.

However, I'm now considering the implications of `net` potentially being `NULL`. Does that seem like a possibility, given all the code I just reviewed? I need to verify, because `trace_fib_table_lookup` accesses `net->net_cookie`.  So I'm checking through each caller, and it looks like `net` is consistently passed from the caller, or it's `rule->fr_net`, which should be valid.  Let me double check that `net_cookie` *is* a field of `struct net`. I think I recall it being so, but I need to make sure.

So, *my current assessment* is that this patch *only* adds tracing information.  It doesn't alter control flow or data structures in a way that would introduce new fuzzing surface. It appears that `net` should be valid in all circumstances, so there's no obvious vulnerability. I'd lean towards marking this as "WorthFuzzing=false" based on the guidelines.

14/2 2026/10/06 16:41 tool grepper
0m Args: 
{
  "Expression": "net_cookie",
  "PathPrefixes": [
    "include/net/net_namespace.h"
  ]
}

Results: 
{
  "Output": "include/net/net_namespace.h=64=struct net {\n--\ninclude/net/net_namespace.h-176-\ninclude/net/net_namespace.h:177:\tu64\t\t\tnet_cookie; /* written once */\ninclude/net/net_namespace.h-178-\n"
}
15/2 2026/10/06 16:41 llm patch-evaluator
1m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 17188
							output: 93
							thoughts: 1498

Thoughts: 
**WorthFuzzing Decision: Negative**

Okay, so I've confirmed that `net_cookie` *is* indeed within `struct net`. Now, let's carefully consider the triage guidelines. The key section is "WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA)." I need to determine if all the modifications fall strictly into one or more of the listed categories.

The patch series in question is about adding `net_cookie` to the `fib_table_lookup` and `fib6_table_lookup` tracepoints. To support this, I had to thread `struct net *net` through `fib_table_lookup()`. This is purely for the tracepoint itself, specifically to allow the tracepoint to log the cookie.

No networking stack control flow or FIB lookup logic was modified in any way. No kernel data structures beyond the tracepoint entry itself are being altered. There are no new assertions or changes to existing ones, and no new kernel logic has been introduced.

Even though there might be minor changes to the assembly generated by the compiler due to the new `net` parameter, the guidelines specifically state that "Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints that do not alter control flow or data structures" are *not* subject to fuzzing.

I've also considered what syzkaller does. Syzkaller generally doesn't fuzz tracepoints unless explicitly enabled or dynamic. More importantly, this change falls into the explicitly excluded category in Section 2: "- Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints that do not alter control flow or data structures."

Re-examining Section 1 and 2, which emphasize reachability and code modification:

*   Reachable code *is* modified, but Section 2's negative criterion explicitly covers this case.

The changes are limited to:

1.  Adding the `net_cookie` field to the `fib_table_lookup` and `fib6_table_lookup` tracepoints.
2.  Updating the `TP_printk` format strings in those tracepoints to print `net_cookie`.
3.  Threading `struct net *net` through `fib_table_lookup` *only* to allow `trace_fib_table_lookup` to access `net->net_cookie`.

This absolutely does *not* alter kernel control flow. There are no `if`, `else`, `switch`, loops, or error returns added, changed, or removed. It does not alter kernel data structures. No `struct fib_table`, `struct flowi4`, `struct fib_result`, or other structures were altered. This change is entirely focused on the tracepoint arguments and internal trace event entries.

Therefore, this entire patch series falls under the negative criterion: "Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints that do not alter control flow or data structures."

To confirm, I've checked the parameters I need to pass to `set-results`:

*   `WorthFuzzing`: `false`
*   `Reasoning`: The changes only add `net_cookie` logging to `fib_table_lookup` and `fib6_table_lookup` trace events, and propagate the existing `net` pointer to `fib_table_lookup` solely for the tracepoint, without altering any control flow, logic, or kernel data structures.
*   `FocusSymbols`: `[]` (empty)
*   `EnableConfigs`: `[]` (empty)

I've double-checked the diff again to ensure I'm not missing anything:

*   `include/net/ip_fib.h`: Updated prototypes and inline callers with `net`
*   `include/trace/events/fib.h`: Tracepoint prototype updated with `net`, `net_cookie` added, format string updated
*   `include/trace/events/fib6.h`: `net_cookie` added, format string updated
*   `net/core/filter.c`: Passed `net` to `fib_table_lookup`
*   `net/ipv4/devinet.c`: Passed `net` to `fib_table_lookup`
*   `net/ipv4/fib_frontend.c`: Passed `net` to `fib_table_lookup`
*   `net/ipv4/fib_rules.c`: Passed `rule->fr_net` to `fib_table_lookup`
*   `net/ipv4/fib_semantics.c`: Passed `net` to `fib_table_lookup`
*   `net/ipv4/

16/2 2026/10/06 16:42 tool set-results
0m Args: 
{
  "EnableConfigs": [],
  "FocusSymbols": [],
  "Reasoning": "The patch series only updates the fib_table_lookup and fib6_table_lookup tracepoints to record net-\u003enet_cookie, and plumbs the existing net pointer through fib_table_lookup to pass it to the tracepoint. No control flow, logic, or kernel data structures are altered.",
  "WorthFuzzing": false
}

Results: 
{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch series only updates the fib_table_lookup and fib6_table_lookup tracepoints to record net-\u003enet_cookie, and plumbs the existing net pointer through fib_table_lookup to pass it to the tracepoint. No control flow, logic, or kernel data structures are altered.",
  "WorthFuzzing": false
}
17/1 2026/10/06 16:42 action If
0m Args: 
{
  "WorthFuzzing": false
}

Results: 
null
LLM Calls Summary:
Total Calls Total Tokens Avg Tokens Total Duration (Seconds) Avg Duration (Seconds)
Tool Calls Summary:
Total Calls Total Duration (Seconds) Avg Duration (Seconds)