AI Trajectory


Trajectory: (Expand/Collapse All)
Seq Timestamp Type Name Duration
0/0 2026/10/08 19:08 flow patch-triage
3m Args: 
null

Results: 
{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "KMSANReasoning": "",
  "NeedsKMSAN": false,
  "Reasoning": "The patch solely enhances the fib_table_lookup and fib6_table_lookup tracepoints by recording net_cookie, and updates fib_table_lookup callers to pass struct net * down to the tracepoint. It introduces no changes to control flow, algorithm logic, kernel data structures, or assertions, falling strictly under the non-functional tracepoint/logging criteria.",
  "WorthFuzzing": false
}
1/1 2026/10/08 19:08 action read-patch-diff
0m Args: 
null

Results: 
{
  "PatchDiff": "commit 6feecec50d0e5912f92c58b7e68f0fd48fb42a5c\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Thu Oct 8 19:08:31 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..e0ee14d6ca459 100644\n--- a/include/trace/events/fib.h\n+++ b/include/trace/events/fib.h\n@@ -15,9 +15,10 @@\n TRACE_EVENT(fib_table_lookup,\n \n \tTP_PROTO(u32 tb_id, const struct flowi4 *flp,\n-\t\t const struct fib_nh_common *nhc, int err),\n+\t\t const struct fib_nh_common *nhc, int err,\n+\t\t const struct net *net),\n \n-\tTP_ARGS(tb_id, flp, nhc, err),\n+\tTP_ARGS(tb_id, flp, nhc, err, net),\n \n \tTP_STRUCT__entry(\n \t\t__field(\tu32,\ttb_id\t\t)\n@@ -35,6 +36,7 @@ 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 +92,16 @@ 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 2ed4c706ca9e3..c106d56eb2f71 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 235c51a6f8e55..24def626739b3 100644\n--- a/net/ipv4/fib_semantics.c\n+++ b/net/ipv4/fib_semantics.c\n@@ -1221,7 +1221,7 @@ 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..9ad76de680819 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(tb-\u003etb_id, flp, NULL, -EAGAIN, net);\n \t\treturn -EAGAIN;\n \t}\n \n@@ -1522,7 +1523,8 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,\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\t\t\t       NULL, -EAGAIN,\n+\t\t\t\t\t\t\t       net);\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(tb-\u003etb_id, flp, NULL, err, net);\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(tb-\u003etb_id, flp, nhc, err, net);\n \n \t\t\treturn err;\n \t\t}\n"
}
2/1 2026/10/08 19:08 agent patch-evaluator
3m Model: 
core

Args: 
null

Results: 
{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch solely enhances the fib_table_lookup and fib6_table_lookup tracepoints by recording net_cookie, and updates fib_table_lookup callers to pass struct net * down to the tracepoint. It introduces no changes to control flow, algorithm logic, kernel data structures, or assertions, falling strictly under the non-functional tracepoint/logging criteria.",
  "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 6feecec50d0e5912f92c58b7e68f0fd48fb42a5c
Author: syz-cluster <triage@syzkaller.com>
Date:   Thu Oct 8 19:08:31 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..e0ee14d6ca459 100644
--- a/include/trace/events/fib.h
+++ b/include/trace/events/fib.h
@@ -15,9 +15,10 @@
 TRACE_EVENT(fib_table_lookup,
 
 	TP_PROTO(u32 tb_id, const struct flowi4 *flp,
-		 const struct fib_nh_common *nhc, int err),
+		 const struct fib_nh_common *nhc, int err,
+		 const struct net *net),
 
-	TP_ARGS(tb_id, flp, nhc, err),
+	TP_ARGS(tb_id, flp, nhc, err, net),
 
 	TP_STRUCT__entry(
 		__field(	u32,	tb_id		)
@@ -35,6 +36,7 @@ TRACE_EVENT(fib_table_lookup,
 		__field(	u16,	sport		)
 		__field(	u16,	dport		)
 		__array(char,  name,   IFNAMSIZ )
+		__field(	u64,	net_cookie	)
 	),
 
 	TP_fast_assign(
@@ -90,13 +92,16 @@ 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 2ed4c706ca9e3..c106d56eb2f71 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 235c51a6f8e55..24def626739b3 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1221,7 +1221,7 @@ 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..9ad76de680819 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(tb->tb_id, flp, NULL, -EAGAIN, net);
 		return -EAGAIN;
 	}
 
@@ -1522,7 +1523,8 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
 				 */
 				if (IS_TRIE(pn)) {
 					trace_fib_table_lookup(tb->tb_id, flp,
-							       NULL, -EAGAIN);
+							       NULL, -EAGAIN,
+							       net);
 					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(tb->tb_id, flp, NULL, err, net);
 			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(tb->tb_id, flp, nhc, err, net);
 
 			return err;
 		}

3/2 2026/10/08 19:08 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 7001
							output: 45
							thoughts: 821

Thoughts: 
**Analyzing the Patch for WorthFuzzing**

Okay, let's break this patch down. My initial assessment is: what is the core function of this diff? It looks like there's a signature change for `fib_table_lookup` to accept a `struct net *net` parameter.  Right, I see it now: `include/net/ip_fib.h` has the updated function signature.  Then, inline calls to this function are also updated in `fib_lookup`. Nothing too complicated yet.

I'm now diving deeper. The tracepoint is being updated, which is in `include/trace/events/fib.h`. It adds a `const struct net *net` argument. Okay, and the `TP_STRUCT__entry` is getting a `net_cookie` field, which is being assigned `net->net_cookie` and then printed. This is all getting the `net` pointer to the tracepoint.

Wait a minute, `fib6_table_lookup`!  Is that also getting the `net` struct passed? It looks like it is, with its own `net_cookie` field and assignment. This is consistent. Let's make sure, before making a final judgement. We need to check callers to `fib6_table_lookup` to make sure `net` is being passed.

Now I'm scanning through the updated callers across several files in `net/` directory: `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`. Yes, it's updating those call sites. `fib_trie.c` also updates the definition to accept the `struct net *net`.

Okay, let's step back and consider the "WorthFuzzing" criteria. I have a feeling this could be a tricky case.

My instructions say: *When to return WorthFuzzing=false (NEGATIVE CRITERIA)*

*   "Purely decorative logging (e.g., message strings in pr\_err, printk, dev\_info) or tracepoints that do not alter control flow or data structures."

Here's the million-dollar question: Is this *purely* decorative tracing? It looks like it's *adding* tracepoint fields and passing the `net` structure down to the tracepoint.  It is tracing the network namespace, but not changing the control flow or data structures.

I'm leaning towards "purely decorative" here, but let me double-check. I'll search `include/trace/events/fib6.h` to confirm the `net` passing to `fib6_table_lookup` and tracepoint logic is consistent. Then, and only then, I can make a call.

4/2 2026/10/08 19:09 tool grepper
0m Args: 
{
  "Expression": "fib6_table_lookup",
  "PathPrefixes": [
    "include/trace/events/fib6.h",
    "net/ipv6/"
  ]
}

Results: 
{
  "Output": "include/trace/events/fib6.h-12-\ninclude/trace/events/fib6.h:13:TRACE_EVENT(fib6_table_lookup,\ninclude/trace/events/fib6.h-14-\n--\nnet/ipv6/fib6_rules.c=68=int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,\n--\nnet/ipv6/fib6_rules.c-74-\t\tstruct fib_lookup_arg arg = {\nnet/ipv6/fib6_rules.c:75:\t\t\t.lookup_ptr = fib6_table_lookup,\nnet/ipv6/fib6_rules.c-76-\t\t\t.lookup_data = \u0026oif,\n--\nnet/ipv6/fib6_rules.c-85-\t} else {\nnet/ipv6/fib6_rules.c:86:\t\terr = fib6_table_lookup(net, net-\u003eipv6.fib6_local_tbl, oif,\nnet/ipv6/fib6_rules.c-87-\t\t\t\t\tfl6, res, flags);\nnet/ipv6/fib6_rules.c-88-\t\tif (err || res-\u003ef6i == net-\u003eipv6.fib6_null_entry)\nnet/ipv6/fib6_rules.c:89:\t\t\terr = fib6_table_lookup(net, net-\u003eipv6.fib6_main_tbl,\nnet/ipv6/fib6_rules.c-90-\t\t\t\t\t\toif, fl6, res, flags);\n--\nnet/ipv6/fib6_rules.c=165=static int fib6_rule_action_alt(struct fib_rule *rule, struct flowi *flp,\n--\nnet/ipv6/fib6_rules.c-192-\toif = (int *)arg-\u003elookup_data;\nnet/ipv6/fib6_rules.c:193:\terr = fib6_table_lookup(net, table, *oif, flp6, res, flags);\nnet/ipv6/fib6_rules.c-194-\tif (!err \u0026\u0026 res-\u003ef6i != net-\u003eipv6.fib6_null_entry)\n--\nnet/ipv6/fib6_rules.c=271=INDIRECT_CALLABLE_SCOPE int fib6_rule_action(struct fib_rule *rule,\n--\nnet/ipv6/fib6_rules.c-274-{\nnet/ipv6/fib6_rules.c:275:\tif (arg-\u003elookup_ptr == fib6_table_lookup)\nnet/ipv6/fib6_rules.c-276-\t\treturn fib6_rule_action_alt(rule, flp, flags, arg);\n--\nnet/ipv6/ip6_fib.c=339=int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,\n--\nnet/ipv6/ip6_fib.c-341-{\nnet/ipv6/ip6_fib.c:342:\treturn fib6_table_lookup(net, net-\u003eipv6.fib6_main_tbl, oif, fl6,\nnet/ipv6/ip6_fib.c-343-\t\t\t\t res, flags);\n--\nnet/ipv6/route.c=71=static int ip6_rt_type_to_error(u8 fib6_type);\n--\nnet/ipv6/route.c-74-#include \u003ctrace/events/fib6.h\u003e\nnet/ipv6/route.c:75:EXPORT_TRACEPOINT_SYMBOL_GPL(fib6_table_lookup);\nnet/ipv6/route.c-76-#undef CREATE_TRACE_POINTS\n--\nnet/ipv6/route.c=1265=INDIRECT_CALLABLE_SCOPE struct rt6_info *ip6_pol_route_lookup(struct net *net,\n--\nnet/ipv6/route.c-1310-out:\nnet/ipv6/route.c:1311:\ttrace_fib6_table_lookup(net, \u0026res, table, fl6);\nnet/ipv6/route.c-1312-\n--\nnet/ipv6/route.c=2197=void rt6_age_exceptions(struct fib6_info *f6i,\n--\nnet/ipv6/route.c-2214-/* must be called with rcu lock held */\nnet/ipv6/route.c:2215:int fib6_table_lookup(struct net *net, struct fib6_table *table, int oif,\nnet/ipv6/route.c-2216-\t\t      struct flowi6 *fl6, struct fib6_result *res, int strict)\n--\nnet/ipv6/route.c-2236-\nnet/ipv6/route.c:2237:\ttrace_fib6_table_lookup(net, res, table, fl6);\nnet/ipv6/route.c-2238-\n--\nnet/ipv6/route.c=2242=struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,\n--\nnet/ipv6/route.c-2260-\nnet/ipv6/route.c:2261:\tfib6_table_lookup(net, table, oif, fl6, \u0026res, strict);\nnet/ipv6/route.c-2262-\tif (res.f6i == net-\u003eipv6.fib6_null_entry)\n--\nnet/ipv6/route.c=3088=INDIRECT_CALLABLE_SCOPE struct rt6_info *__ip6_route_redirect(struct net *net,\n--\nnet/ipv6/route.c-3166-\nnet/ipv6/route.c:3167:\ttrace_fib6_table_lookup(net, \u0026res, table, fl6);\nnet/ipv6/route.c-3168-\treturn ret;\n--\nnet/ipv6/route.c=3363=static int ip6_nh_lookup_table(struct net *net, struct fib6_config *cfg,\n--\nnet/ipv6/route.c-3383-\nnet/ipv6/route.c:3384:\terr = fib6_table_lookup(net, table, cfg-\u003efc_ifindex, \u0026fl6, res, flags);\nnet/ipv6/route.c-3385-\tif (!err \u0026\u0026 res-\u003ef6i != net-\u003eipv6.fib6_null_entry)\n"
}
5/2 2026/10/08 19:09 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 10118
							output: 36
							thoughts: 27

Thoughts: 
Here's my summary, as if I were thinking these thoughts:

**Examining the Fib6 Tracepoint Definition**

Okay, let's dive right in. I need to refresh my memory on the structure of this `fib6` tracepoint, so I'll start by taking a peek at the source code. Let's use `read-file` to get the contents of `include/trace/events/fib6.h` and focus specifically on lines 1 through 35. That should be enough to capture the crucial parts - the likely macro definitions, struct declarations, or function prototypes that define the core event data. I expect to find the fields that the tracer will be capturing when this tracepoint is hit. It's usually pretty straightforward, but a quick review will make sure I'm on solid ground before proceeding. No need to waste time making assumptions when the source is right here!

6/2 2026/10/08 19:09 tool read-file
0m Args: 
{
  "File": "include/trace/events/fib6.h",
  "FirstLine": 1,
  "LineCount": 40
}

Results: 
{
  "Contents": "   1:\t/* SPDX-License-Identifier: GPL-2.0 */\n   2:\t#undef TRACE_SYSTEM\n   3:\t#define TRACE_SYSTEM fib6\n   4:\t\n   5:\t#if !defined(_TRACE_FIB6_H) || defined(TRACE_HEADER_MULTI_READ)\n   6:\t#define _TRACE_FIB6_H\n   7:\t\n   8:\t#include \u003clinux/in6.h\u003e\n   9:\t#include \u003cnet/flow.h\u003e\n  10:\t#include \u003cnet/ip6_fib.h\u003e\n  11:\t#include \u003clinux/tracepoint.h\u003e\n  12:\t\n  13:\tTRACE_EVENT(fib6_table_lookup,\n  14:\t\n  15:\t\tTP_PROTO(const struct net *net, const struct fib6_result *res,\n  16:\t\t\t struct fib6_table *table, const struct flowi6 *flp),\n  17:\t\n  18:\t\tTP_ARGS(net, res, table, flp),\n  19:\t\n  20:\t\tTP_STRUCT__entry(\n  21:\t\t\t__field(\tu32,\ttb_id\t\t)\n  22:\t\t\t__field(\tint,\terr\t\t)\n  23:\t\t\t__field(\tint,\toif\t\t)\n  24:\t\t\t__field(\tint,\tiif\t\t)\n  25:\t\t\t__field(\tu32,\tflowlabel\t)\n  26:\t\t\t__field(\t__u8,\ttos\t\t)\n  27:\t\t\t__field(\t__u8,\tscope\t\t)\n  28:\t\t\t__field(\t__u8,\tflags\t\t)\n  29:\t\t\t__array(\t__u8,\tsrc,\t16\t)\n  30:\t\t\t__array(\t__u8,\tdst,\t16\t)\n  31:\t\t\t__field(        u16,\tsport\t\t)\n  32:\t\t\t__field(        u16,\tdport\t\t)\n  33:\t\t\t__field(        u8,\tproto\t\t)\n  34:\t\t\t__field(        u8,\trt_type\t\t)\n  35:\t\t\t__array(\t\tchar,\tname,\tIFNAMSIZ )\n  36:\t\t\t__array(\t\t__u8,\tgw,\t16\t )\n  37:\t\t\t__field(\tu64,\tnet_cookie\t)\n  38:\t\t),\n  39:\t\n  40:\t\tTP_fast_assign(\n"
}
7/2 2026/10/08 19:09 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 11009
							output: 40
							thoughts: 1223

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

Okay, so this patch is adding `net_cookie` to the `trace_fib_table_lookup` tracepoint, which makes me think this might be relevant. It looks like `fib6_table_lookup` already took `const struct net *net` in `TP_PROTO`, but the IPv4 counterpart, `fib_table_lookup`, didn't, so the patch author has to add it. This means the signature of `fib_table_lookup` is changing, and all its callers are getting updated to include `net` as an argument.

Now, let's carefully go over those negative criteria. I have to see if this change falls *strictly* into one of those categories, or not.

The first one, "Non-kernel and non-executable changes," doesn't seem to apply, since we're modifying kernel code. The "Structurally unreachable hardware" is out too. That leaves "Unreachable execution paths" and "Purely decorative logging" as the only relevant possibilities here.

The crucial point is: "Purely decorative logging (e.g., message strings... or tracepoints that do not alter control flow or data structures)." So, does this patch alter control flow or data structures? Let's break it down file by file:

1.  `include/net/ip_fib.h`: We're changing the `fib_table_lookup` signature and passing the `net` struct. And in the inline functions, `net` is passed to the modified `fib_table_lookup()` function.

2.  `include/trace/events/fib.h`:  A parameter `net` is added and passed to the tracepoint. We are adding `net_cookie` to the tracepoint struct and setting it to `net->net_cookie`. The `TP_printk` is getting an update. It does sound like a change to data structures and how they are accessed.

3.  `include/trace/events/fib6.h`:  Same as `fib.h`: We're adding `net_cookie`, populating it, and updating the `TP_printk`. Definitely a data structure change.

4.  `net/core/filter.c`: Calls to `fib_table_lookup` are updated to pass `net`. Control flow remains the same, but the call's parameters now vary.

5.  `net/ipv4/devinet.c`: Similarly, `net` is being passed to `fib_table_lookup`.

6.  `net/ipv4/fib_frontend.c`: Same story, `net` is added as an argument to the `fib_table_lookup` call in multiple functions.

7.  `net/ipv4/fib_rules.c`:  The code is passing `rule->fr_net` to `fib_table_lookup`, so `net` is passed to the function call.

8.  `net/ipv4/fib_semantics.c`: `net` is being passed to a call to `fib_table_lookup`.

9.  `net/ipv4/fib_trie.c`: We're calling `trace_fib_table_lookup` and passing `net` there. We will need to check what `fib_table_lookup` is doing with `net` other than just calling `trace_fib_table_lookup`. I'll want to inspect lines 1415-1620 to be sure.

So, this patch isn't *just* decorative logging. It modifies data structures (the tracepoint struct, the `fib_table_lookup` function signature), and changes how `net` is handled throughout the IPv4 FIB code, and adds it as an argument in several places. It's a data structure change. This is not purely decorative logging. It changes the function signature, and passes that information to a tracepoint. I'm going to say this is not purely decorative.

Now, I'm going to double-check that `fib_trie.c` code to make sure `net` isn't doing anything else critical. And then, I can confirm that this patch is, in fact, worth fuzzing.

8/2 2026/10/08 19:09 tool read-file
0m Args: 
{
  "File": "net/ipv4/fib_trie.c",
  "FirstLine": 1417,
  "LineCount": 50
}

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(tb-\u003etb_id, flp, NULL, -EAGAIN, net);\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;\n"
}
9/2 2026/10/08 19:09 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 13970
							output: 41
							thoughts: 30

Thoughts: 
Okay, here's my take on those thoughts, tailored for an expert audience:

**Diving Back into `fib_trie.c`'s Core Logic**

Alright, I'm heading back into `net/ipv4/fib_trie.c`, specifically focusing on lines 1467-1620. Given where we are, I suspect we're deep into either a major lookup operation, potentially an insertion or deletion routine concerning FIB entries, or perhaps dealing with the mechanics of how the trie is being updated. I want to quickly refresh my understanding of the data structures involved—what are we dealing with, conceptually, at this point in the code? Is this related to the recent performance issues we were seeing with large routing tables? Are we optimizing for memory access patterns, or is the focus purely on latency? My goal is to quickly pinpoint what this specific section is responsible for. It could be something I need to explain better to the team. Let's dig in.

10/2 2026/10/08 19:09 tool read-file
0m Args: 
{
  "File": "net/ipv4/fib_trie.c",
  "FirstLine": 1515,
  "LineCount": 100
}

Results: 
{
  "Contents": "1515:\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(tb-\u003etb_id, flp,\n1526:\t\t\t\t\t\t\t\t       NULL, -EAGAIN,\n1527:\t\t\t\t\t\t\t\t       net);\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(tb-\u003etb_id, flp, NULL, err, net);\n1575:\t\t\t\treturn err;\n1576:\t\t\t}\n1577:\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\n"
}
11/2 2026/10/08 19:09 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 15806
							output: 40
							thoughts: 16

Thoughts: 
Okay, here's the summary, rendered as a first-person thought process, keeping in mind the user is an expert:

**Navigating the Codebase: Targeted Inspection**

Alright, I'm going to zero in on lines 1610-1630. This section warrants closer examination. Based on the surrounding code, my initial assessment suggests that [***I am looking at the code I know best and can predict the nature of what might happen.***] Given the context, my expert intuition is that the logic within this block is likely dealing with [***some of what the code is doing or a problem I have.***]. It's probably responsible for [***a feature, a fix, or a potential issue***], and I need to verify that it's behaving as expected. I'll need to confirm that [***certain variable or parameter***] is handled correctly under the given conditions. Let's dig in and make sure there are no surprises in store. I have a hunch that something could be awry here.

12/2 2026/10/08 19:10 tool read-file
0m Args: 
{
  "File": "net/ipv4/fib_trie.c",
  "FirstLine": 1610,
  "LineCount": 25
}

Results: 
{
  "Contents": "1610:\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(tb-\u003etb_id, flp, nhc, err, net);\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\n"
}
13/2 2026/10/08 19:10 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 16485
							output: 19
							thoughts: 1168

Thoughts: 
**Analysis of `fib_table_lookup` for Fuzzing Suitability**

Okay, so the initial thought is that `net` in `fib_table_lookup` is *only* used for the `trace_fib_table_lookup` call. Let's make sure, though. I'm going to quickly confirm that `net` isn't used anywhere else in the function itself, and that no control flow or kernel data structures are modified beyond the tracepoint.

Hold on, what about those data structures? The tracepoint event structs in `include/trace/events/fib.h` and `fib6.h` are modified. Specifically, the `net_cookie` field is added, and assigned. This is also reflected in the tracepoint signature and format string.

Now, let's go back and carefully re-read those negative criteria. The key line here 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."

Wait... could `net` *ever* be NULL? I need to check the callers. Could any of the callers pass NULL to `fib_table_lookup`?

Let's look at all the call sites in the kernel:

1.  `include/net/ip_fib.h`: `fib_lookup` calls `fib_table_lookup` with an existing `net` pointer in both inline scenarios (!CONFIG\_IP\_MULTIPLE\_TABLES and otherwise).
2.  `net/core/filter.c`: `bpf_ipv4_fib_lookup` passes `net`.
3.  `net/ipv4/devinet.c`: `__ip_dev_find` passes `net`.
4.  `net/ipv4/fib_frontend.c`: Both `__inet_dev_addr_type` and `nl_fib_lookup` pass `net`.
5.  `net/ipv4/fib_rules.c`: `fib4_rule_action` passes `rule->fr_net` (which should be safe).
6.  `net/ipv4/fib_semantics.c`: `fib_check_nh_v4_gw` passes `net`.

Okay, so every caller *does* have a `net` pointer, and it's passed directly to `fib_table_lookup`. Also, the net pointer is *only* passed to `trace_fib_table_lookup`.

Hang on, what about `include/trace/events/fib6.h`? In `fib6_table_lookup`, `TP_PROTO` already includes `const struct net *net`, and the `TP_fast_assign` part just adds `__entry->net_cookie = net->net_cookie;` and prints it.

Okay, is there anything else? Let's check the files in this patch to be sure: `include/net/ip_fib.h`, `include/trace/events/fib.h`, `include/trace/events/fib6.h`, `net/core/filter.c`, `net/ipv4/devinet.c`, `net/ipv4/fib_frontend.c`, `net/ipv4/fib_rules.c`, `net/ipv4/fib_semantics.c`, `net/ipv4/fib_trie.c`

Wait! We should confirm this is the *only* place `fib_table_lookup` is called. Just to be absolutely sure there are no other call sites, let's use `grepper`.

14/2 2026/10/08 19:10 tool grepper
0m Args: 
{
  "Expression": "fib_table_lookup"
}

Results: 
{
  "Output": "include/net/ip_fib.h=266=struct fib_dump_filter {\n--\ninclude/net/ip_fib.h-277-\ninclude/net/ip_fib.h:278:int fib_table_lookup(struct net *net, struct fib_table *tb,\ninclude/net/ip_fib.h-279-\t\t     const struct flowi4 *flp, struct fib_result *res,\n--\ninclude/net/ip_fib.h=317=static inline int fib_lookup(struct net *net, const struct flowi4 *flp,\n--\ninclude/net/ip_fib.h-326-\tif (tb)\ninclude/net/ip_fib.h:327:\t\terr = fib_table_lookup(net, tb, flp, res,\ninclude/net/ip_fib.h-328-\t\t\t\t       flags | FIB_LOOKUP_NOREF);\n--\ninclude/net/ip_fib.h=376=static inline int fib_lookup(struct net *net, struct flowi4 *flp,\n--\ninclude/net/ip_fib.h-391-\tif (tb)\ninclude/net/ip_fib.h:392:\t\terr = fib_table_lookup(net, tb, flp, res, flags);\ninclude/net/ip_fib.h-393-\n--\ninclude/net/ip_fib.h-398-\tif (tb)\ninclude/net/ip_fib.h:399:\t\terr = fib_table_lookup(net, tb, flp, res, flags);\ninclude/net/ip_fib.h-400-\n--\ninclude/net/nexthop.h=400=struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel)\n--\ninclude/net/nexthop.h-421-\ninclude/net/nexthop.h:422:/* called from fib_table_lookup with rcu_lock */\ninclude/net/nexthop.h-423-static inline\n--\ninclude/trace/events/fib.h-14-\ninclude/trace/events/fib.h:15:TRACE_EVENT(fib_table_lookup,\ninclude/trace/events/fib.h-16-\n--\nkernel/bpf/btf.c=6710=static const struct bpf_raw_tp_null_args raw_tp_null_args[] = {\n--\nkernel/bpf/btf.c-6740-\t/* fib */\nkernel/bpf/btf.c:6741:\t{ \"fib_table_lookup\", 0x100 },\nkernel/bpf/btf.c-6742-\t/* filelock */\n--\nnet/core/filter.c=6350=static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,\n--\nnet/core/filter.c-6415-\nnet/core/filter.c:6416:\t\terr = fib_table_lookup(net, tb, \u0026fl4, \u0026res, FIB_LOOKUP_NOREF);\nnet/core/filter.c-6417-\t} else {\n--\nnet/ipv4/devinet.c=143=struct net_device *__ip_dev_find(struct net *net, __be32 addr, bool devref)\n--\nnet/ipv4/devinet.c-159-\t\tif (local \u0026\u0026\nnet/ipv4/devinet.c:160:\t\t    !fib_table_lookup(net, local, \u0026fl4, \u0026res,\nnet/ipv4/devinet.c-161-\t\t\t\t      FIB_LOOKUP_NOREF) \u0026\u0026\n--\nnet/ipv4/fib_frontend.c=227=static inline unsigned int __inet_dev_addr_type(struct net *net,\n--\nnet/ipv4/fib_frontend.c-245-\t\tret = RTN_UNICAST;\nnet/ipv4/fib_frontend.c:246:\t\tif (!fib_table_lookup(net, table, \u0026fl4, \u0026res,\nnet/ipv4/fib_frontend.c-247-\t\t\t\t      FIB_LOOKUP_NOREF)) {\n--\nnet/ipv4/fib_frontend.c=1383=static void nl_fib_lookup(struct net *net, struct fib_result_nl *frn)\n--\nnet/ipv4/fib_frontend.c-1403-\t\tfrn-\u003etb_id = tb-\u003etb_id;\nnet/ipv4/fib_frontend.c:1404:\t\tfrn-\u003eerr = fib_table_lookup(net, tb, \u0026fl4, \u0026res,\nnet/ipv4/fib_frontend.c-1405-\t\t\t\t\t    FIB_LOOKUP_NOREF);\n--\nnet/ipv4/fib_rules.c=111=INDIRECT_CALLABLE_SCOPE int fib4_rule_action(struct fib_rule *rule,\n--\nnet/ipv4/fib_rules.c-138-\tif (tbl)\nnet/ipv4/fib_rules.c:139:\t\terr = fib_table_lookup(rule-\u003efr_net, tbl, \u0026flp-\u003eu.ip4,\nnet/ipv4/fib_rules.c-140-\t\t\t\t       (struct fib_result *)arg-\u003eresult,\n--\nnet/ipv4/fib_semantics.c=249=void fib_release_info(struct fib_info *fi)\n--\nnet/ipv4/fib_semantics.c-266-\t\t}\nnet/ipv4/fib_semantics.c:267:\t\t/* Paired with READ_ONCE() from fib_table_lookup() */\nnet/ipv4/fib_semantics.c-268-\t\tWRITE_ONCE(fi-\u003efib_dead, 1);\n--\nnet/ipv4/fib_semantics.c=1171=static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,\n--\nnet/ipv4/fib_semantics.c-1223-\t\tif (tbl)\nnet/ipv4/fib_semantics.c:1224:\t\t\terr = fib_table_lookup(net, tbl, \u0026fl4, \u0026res,\nnet/ipv4/fib_semantics.c-1225-\t\t\t\t\t       FIB_LOOKUP_IGNORE_LINKSTATE |\n--\nnet/ipv4/fib_semantics.c=1376=struct fib_info *fib_create_info(struct fib_config *cfg,\n--\nnet/ipv4/fib_semantics.c-1560-\tif (ofi) {\nnet/ipv4/fib_semantics.c:1561:\t\t/* fib_table_lookup() should not see @fi yet. */\nnet/ipv4/fib_semantics.c-1562-\t\tfi-\u003efib_dead = 1;\n--\nnet/ipv4/fib_semantics.c-1598-\tif (fi) {\nnet/ipv4/fib_semantics.c:1599:\t\t/* fib_table_lookup() should not see @fi yet. */\nnet/ipv4/fib_semantics.c-1600-\t\tfi-\u003efib_dead = 1;\n--\nnet/ipv4/fib_trie.c=1402=bool fib_lookup_good_nhc(const struct fib_nh_common *nhc, int fib_flags,\n--\nnet/ipv4/fib_trie.c-1419-/* should be called with rcu_read_lock */\nnet/ipv4/fib_trie.c:1420:int fib_table_lookup(struct net *net, struct fib_table *tb,\nnet/ipv4/fib_trie.c-1421-\t\t     const struct flowi4 *flp, struct fib_result *res,\n--\nnet/ipv4/fib_trie.c-1438-\tif (!n) {\nnet/ipv4/fib_trie.c:1439:\t\ttrace_fib_table_lookup(tb-\u003etb_id, flp, NULL, -EAGAIN, net);\nnet/ipv4/fib_trie.c-1440-\t\treturn -EAGAIN;\n--\nnet/ipv4/fib_trie.c-1524-\t\t\t\tif (IS_TRIE(pn)) {\nnet/ipv4/fib_trie.c:1525:\t\t\t\t\ttrace_fib_table_lookup(tb-\u003etb_id, flp,\nnet/ipv4/fib_trie.c-1526-\t\t\t\t\t\t\t       NULL, -EAGAIN,\n--\nnet/ipv4/fib_trie.c-1573-#endif\nnet/ipv4/fib_trie.c:1574:\t\t\ttrace_fib_table_lookup(tb-\u003etb_id, flp, NULL, err, net);\nnet/ipv4/fib_trie.c-1575-\t\t\treturn err;\n--\nnet/ipv4/fib_trie.c-1614-#endif\nnet/ipv4/fib_trie.c:1615:\t\t\ttrace_fib_table_lookup(tb-\u003etb_id, flp, nhc, err, net);\nnet/ipv4/fib_trie.c-1616-\n--\nnet/ipv4/fib_trie.c-1625-}\nnet/ipv4/fib_trie.c:1626:EXPORT_SYMBOL_GPL(fib_table_lookup);\nnet/ipv4/fib_trie.c-1627-\n--\ntools/testing/selftests/net/fib_tests.sh=2646=mpath_dep_check()\n--\ntools/testing/selftests/net/fib_tests.sh-2667-\ntools/testing/selftests/net/fib_tests.sh:2668:\tperf list fib:* | grep -q fib_table_lookup\ntools/testing/selftests/net/fib_tests.sh-2669-\tif [ $? -ne 0 ]; then\n--\ntools/testing/selftests/net/fib_tests.sh=2706=ipv4_mpath_list_test()\n--\ntools/testing/selftests/net/fib_tests.sh-2741-\tlocal t0_rx_pkts=$(link_stats_get $ns2 veth2 rx packets)\ntools/testing/selftests/net/fib_tests.sh:2742:\trun_cmd \"perf stat -a -e fib:fib_table_lookup --filter 'err == 0' -j -o $tmp_file -- $cmd\"\ntools/testing/selftests/net/fib_tests.sh-2743-\tlocal t1_rx_pkts=$(link_stats_get $ns2 veth2 rx packets)\n"
}
15/2 2026/10/08 19:10 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 21155
							output: 38
							thoughts: 58

Thoughts: 
Okay, let's dive in. I need to understand this snippet of code a bit better.

**Inspecting `kernel/bpf/btf.c`**

Alright, I'm heading straight for `kernel/bpf/btf.c`. I'm curious about this particular entry: `{ "fib_table_lookup", 0x100 }`. What's the context here? 0x100 is a fairly specific value. I need to understand what "fib_table_lookup" represents in relation to this hexadecimal value. This suggests some kind of function pointer or BPF metadata. It's time to dig deeper and see what's happening.

16/2 2026/10/08 19:10 tool read-file
0m Args: 
{
  "File": "kernel/bpf/btf.c",
  "FirstLine": 6705,
  "LineCount": 45
}

Results: 
{
  "Contents": "6705:\tstruct bpf_raw_tp_null_args {\n6706:\t\tconst char *func;\n6707:\t\tu64 mask;\n6708:\t};\n6709:\t\n6710:\tstatic const struct bpf_raw_tp_null_args raw_tp_null_args[] = {\n6711:\t\t/* sched */\n6712:\t\t{ \"sched_pi_setprio\", 0x10 },\n6713:\t\t/*\n6714:\t\t * do_wait() passes NULL for wait4(-1) and waitid(P_ALL).\n6715:\t\t */\n6716:\t\t{ \"sched_process_wait\", 0x1 },\n6717:\t\t/* ... from sched_numa_pair_template event class */\n6718:\t\t{ \"sched_stick_numa\", 0x100 },\n6719:\t\t{ \"sched_swap_numa\", 0x100 },\n6720:\t\t/* afs */\n6721:\t\t{ \"afs_make_fs_call\", 0x10 },\n6722:\t\t{ \"afs_make_fs_calli\", 0x10 },\n6723:\t\t{ \"afs_make_fs_call1\", 0x10 },\n6724:\t\t{ \"afs_make_fs_call2\", 0x10 },\n6725:\t\t{ \"afs_protocol_error\", 0x1 },\n6726:\t\t{ \"afs_flock_ev\", 0x10 },\n6727:\t\t/* cachefiles */\n6728:\t\t{ \"cachefiles_lookup\", 0x1 | 0x200 },\n6729:\t\t{ \"cachefiles_unlink\", 0x1 },\n6730:\t\t{ \"cachefiles_rename\", 0x1 },\n6731:\t\t{ \"cachefiles_prep_read\", 0x1 },\n6732:\t\t{ \"cachefiles_mark_active\", 0x1 },\n6733:\t\t{ \"cachefiles_mark_failed\", 0x1 },\n6734:\t\t{ \"cachefiles_mark_inactive\", 0x1 },\n6735:\t\t{ \"cachefiles_vfs_error\", 0x1 },\n6736:\t\t{ \"cachefiles_io_error\", 0x1 },\n6737:\t\t/* ext4, from ext4__mballoc event class */\n6738:\t\t{ \"ext4_mballoc_discard\", 0x10 },\n6739:\t\t{ \"ext4_mballoc_free\", 0x10 },\n6740:\t\t/* fib */\n6741:\t\t{ \"fib_table_lookup\", 0x100 },\n6742:\t\t/* filelock */\n6743:\t\t/* ... from filelock_lock event class */\n6744:\t\t{ \"posix_lock_inode\", 0x10 },\n6745:\t\t{ \"fcntl_setlk\", 0x10 },\n6746:\t\t{ \"locks_remove_posix\", 0x10 },\n6747:\t\t{ \"flock_lock_inode\", 0x10 },\n6748:\t\t/* ... from filelock_lease event class */\n6749:\t\t{ \"break_lease_noblock\", 0x10 },\n"
}
17/2 2026/10/08 19:10 llm patch-evaluator
0m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 22267
							output: 33
							thoughts: 21

Thoughts: 
Here's my understanding of the situation, presented from my perspective as an expert:

**Investigating `raw_tp_null_args` in `btf.c`**

Alright, let's dive in and dissect what's happening with `raw_tp_null_args` within `btf.c`. I need to get a clear picture of its functionality. What exactly does this function contribute to the larger BTF (BPF Type Format) picture? Is it handling null arguments in tracepoint contexts? Perhaps it's dealing with edge cases or error conditions? Or maybe it's involved in more routine type handling. I have a hunch it is related to how tracepoints deal with missing argument metadata and how BTF data is used to resolve them. Let's see if this function is related to an edge-case or error-handling scenario, or something more fundamental to the type information for those arguments. My guess is it's related to handling situations where tracepoints are invoked with fewer arguments than expected, and we're using BTF to manage that gracefully.

18/2 2026/10/08 19:10 tool grepper
0m Args: 
{
  "Expression": "raw_tp_null_args",
  "PathPrefixes": [
    "kernel/bpf/"
  ]
}

Results: 
{
  "Output": "kernel/bpf/btf.c=6685=int btf_ctx_arg_offset(const struct btf *btf, const struct btf_type *func_proto,\n--\nkernel/bpf/btf.c-6704-\nkernel/bpf/btf.c:6705:struct bpf_raw_tp_null_args {\nkernel/bpf/btf.c-6706-\tconst char *func;\n--\nkernel/bpf/btf.c-6709-\nkernel/bpf/btf.c:6710:static const struct bpf_raw_tp_null_args raw_tp_null_args[] = {\nkernel/bpf/btf.c-6711-\t/* sched */\n--\nkernel/bpf/btf.c=6902=bool btf_ctx_access(int off, int size, enum bpf_access_type type,\n--\nkernel/bpf/btf.c-7085-\t\ttname += sizeof(\"btf_trace_\") - 1;\nkernel/bpf/btf.c:7086:\t\tfor (i = 0; i \u003c ARRAY_SIZE(raw_tp_null_args); i++) {\nkernel/bpf/btf.c-7087-\t\t\t/* Is this a func with potential NULL args? */\nkernel/bpf/btf.c:7088:\t\t\tif (strcmp(tname, raw_tp_null_args[i].func))\nkernel/bpf/btf.c-7089-\t\t\t\tcontinue;\nkernel/bpf/btf.c:7090:\t\t\tif (raw_tp_null_args[i].mask \u0026 (0x1ULL \u003c\u003c (arg * 4)))\nkernel/bpf/btf.c-7091-\t\t\t\tinfo-\u003ereg_type |= PTR_MAYBE_NULL;\nkernel/bpf/btf.c-7092-\t\t\t/* Is the current arg IS_ERR? */\nkernel/bpf/btf.c:7093:\t\t\tif (raw_tp_null_args[i].mask \u0026 (0x2ULL \u003c\u003c (arg * 4)))\nkernel/bpf/btf.c-7094-\t\t\t\tptr_err_raw_tp = true;\n--\nkernel/bpf/btf.c-7100-\t\t */\nkernel/bpf/btf.c:7101:\t\tif (i == ARRAY_SIZE(raw_tp_null_args) \u0026\u0026 btf_is_module(btf))\nkernel/bpf/btf.c-7102-\t\t\tinfo-\u003ereg_type |= PTR_MAYBE_NULL;\n"
}
19/2 2026/10/08 19:10 llm patch-evaluator
1m Model: 
gemini-3.8-flash

Args: 
null

Results: 
null

Tokens: 
							input: 23212
							output: 106
							thoughts: 4654

Thoughts: 
**Analysis of the Patch: WorthFuzzing = False**

Okay, let's break this down. My initial observation flags a potential issue: the code modifies `kernel/bpf/btf.c`, specifically related to `fib_table_lookup`. The key is that `nhc` (a potential null pointer) can influence the bitwise operation, but this is immediately caught in the `tracepoint` logic. This tracepoint adds an extra argument, `net`, which is the 5th argument. My task is to determine if this patch requires fuzzing. The provided core triage philosophy states a clear goal: discover crashes, regressions, and new bugs. Crucially, reachability is the primary gate, and changes must be fuzzed if they are not strictly non-executable changes like purely decorative logging or tracepoints that don't change control flow.

I've examined the detailed changes in `include/trace/events/fib.h`, `include/trace/events/fib6.h`, and related files, specifically looking for alterations to data structures or control flow. The patch primarily introduces `net_cookie` to the trace event entries and adds the `net` parameter to `fib_table_lookup`. The `net_cookie` is obtained from `net->net_cookie`, which I checked through the callers to ensure it's not a null pointer. The logic isn't rearranged, no helper functions are introduced, and no state management is altered, thus no semantic shifts.

This *precisely* aligns with the "negative criteria" in the instructions: "Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints that do not alter control flow or data structures." It's purely decorative because it's adding observability through a tracepoint. I confirmed no code logic was changed - just passing the net pointer to a tracepoint function. Critically, there's no alteration of kernel data structures beyond the trace event entry itself. `struct net`, `struct fib_table`, `struct flowi4`, `struct fib_result` are untouched. This patch doesn't meet the "positive criteria," which would have included code modifications in core subsystems, refactoring of data structures, or the introduction of assertions. Since nothing is changed, the `net` pointer will always be valid, and the function isn't called unless the tracepoint is enabled.

I've verified no subtle side effects exist, and the patch strictly serves to add `net_cookie` to tracepoints without behavioral changes or logic modifications. Therefore, `WorthFuzzing` is unequivocally `false`, and I will now call `set-results`.

20/2 2026/10/08 19:11 tool set-results
0m Args: 
{
  "EnableConfigs": [],
  "FocusSymbols": [],
  "Reasoning": "The patch solely enhances the fib_table_lookup and fib6_table_lookup tracepoints by recording net_cookie, and updates fib_table_lookup callers to pass struct net * down to the tracepoint. It introduces no changes to control flow, algorithm logic, kernel data structures, or assertions, falling strictly under the non-functional tracepoint/logging criteria.",
  "WorthFuzzing": false
}

Results: 
{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch solely enhances the fib_table_lookup and fib6_table_lookup tracepoints by recording net_cookie, and updates fib_table_lookup callers to pass struct net * down to the tracepoint. It introduces no changes to control flow, algorithm logic, kernel data structures, or assertions, falling strictly under the non-functional tracepoint/logging criteria.",
  "WorthFuzzing": false
}
21/1 2026/10/08 19:11 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)