AI Trajectory

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "KMSANReasoning": "",
  "NeedsKMSAN": false,
  "Reasoning": "The patch only modifies user-space tools (bpftool) and BPF selftests under tools/, with no changes affecting the compiled kernel image or modules.",
  "WorthFuzzing": false
}

null

{
  "PatchDiff": "commit d7746e032ed8bafeb18ebc38e08f8b7f2a55f78a\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Sat Sep 5 12:56:10 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c\nindex a50540ef6521c..1583150241c88 100644\n--- a/tools/bpf/bpftool/gen.c\n+++ b/tools/bpf/bpftool/gen.c\n@@ -1340,6 +1340,12 @@ static int do_skeleton(int argc, char **argv)\n \t}\n \tbpf_object__for_each_program(prog, obj) {\n \t\tprog_cnt++;\n+\n+\t\tif (use_loader \u0026\u0026 !bpf_program__autoload(prog)) {\n+\t\t\tp_err(\"program '%s' is marked as non-autoload, which is not supported for light skeletons\",\n+\t\t\t      bpf_program__name(prog));\n+\t\t\treturn -1;\n+\t\t}\n \t}\n \n \tget_header_guard(header_guard, obj_name, \"SKEL_H\");\ndiff --git a/tools/testing/selftests/bpf/prog_tests/global_data_init.c b/tools/testing/selftests/bpf/prog_tests/global_data_init.c\nindex 7c539cbcf3a1e..dbb7de534f7de 100644\n--- a/tools/testing/selftests/bpf/prog_tests/global_data_init.c\n+++ b/tools/testing/selftests/bpf/prog_tests/global_data_init.c\n@@ -3,6 +3,7 @@\n #include \"bpf/libbpf_internal.h\"\n #include \"test_global_percpu_data.skel.h\"\n #include \"test_global_percpu_data.lskel.h\"\n+#include \"test_global_percpu_data_failure.skel.h\"\n \n void test_global_data_init(void)\n {\n@@ -372,7 +373,7 @@ static void test_global_percpu_data_rdonly_direct_write(void)\n \n static void test_global_percpu_data_verifier_log(void)\n {\n-\tRUN_TESTS(test_global_percpu_data);\n+\tRUN_TESTS(test_global_percpu_data_failure);\n }\n \n static void test_global_percpu_data_iter(void)\ndiff --git a/tools/testing/selftests/bpf/progs/test_global_percpu_data.c b/tools/testing/selftests/bpf/progs/test_global_percpu_data.c\nindex 2765cd46e9af0..bc748df4a6cc8 100644\n--- a/tools/testing/selftests/bpf/progs/test_global_percpu_data.c\n+++ b/tools/testing/selftests/bpf/progs/test_global_percpu_data.c\n@@ -42,29 +42,6 @@ int update_percpu_data(void *ctx)\n \treturn 0;\n }\n \n-static const char fmt[] SEC(\".percpu.fmt\") = \"data %d\\n\";\n-\n-SEC(\"?kprobe\")\n-__failure __msg(\"R{{[0-9]+}} points to percpu_array map which cannot be used as const string\")\n-int verifier_strncmp(void *ctx)\n-{\n-\treturn bpf_strncmp(\"test\", 5, fmt);\n-}\n-\n-SEC(\"?kprobe\")\n-__failure __msg(\"R{{[0-9]+}} points to percpu_array map which cannot be used as const string\")\n-int verifier_snprintf(void *ctx)\n-{\n-\tu64 args[] = { data };\n-\tchar buf[128];\n-\tint len;\n-\n-\tlen = bpf_snprintf(buf, sizeof(buf), fmt, args, sizeof(args));\n-\tif (len \u003e 0)\n-\t\tbpf_printk(\"snprintf: %s\\n\", buf);\n-\treturn 0;\n-}\n-\n volatile const __u32 num_cpus = 0;\n volatile const int num_off;\n volatile const int elem_sz;\ndiff --git a/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c b/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c\nnew file mode 100644\nindex 0000000000000..3a823acb42d74\n--- /dev/null\n+++ b/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c\n@@ -0,0 +1,30 @@\n+// SPDX-License-Identifier: GPL-2.0\n+#include \u003cvmlinux.h\u003e\n+#include \u003cbpf/bpf_helpers.h\u003e\n+#include \"bpf_misc.h\"\n+\n+int data SEC(\".percpu\") = -1;\n+static const char fmt[] SEC(\".percpu.fmt\") = \"data %d\\n\";\n+\n+SEC(\"?kprobe\")\n+__failure __msg(\"R{{[0-9]+}} points to percpu_array map which cannot be used as const string\")\n+int verifier_strncmp(void *ctx)\n+{\n+\treturn bpf_strncmp(\"test\", 5, fmt);\n+}\n+\n+SEC(\"?kprobe\")\n+__failure __msg(\"R{{[0-9]+}} points to percpu_array map which cannot be used as const string\")\n+int verifier_snprintf(void *ctx)\n+{\n+\tu64 args[] = { data };\n+\tchar buf[128];\n+\tint len;\n+\n+\tlen = bpf_snprintf(buf, sizeof(buf), fmt, args, sizeof(args));\n+\tif (len \u003e 0)\n+\t\tbpf_printk(\"snprintf: %s\\n\", buf);\n+\treturn 0;\n+}\n+\n+char _license[] SEC(\"license\") = \"GPL\";\n"
}

core

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch only modifies user-space tools (bpftool) and BPF selftests under tools/, with no changes affecting the compiled kernel image or modules.",
  "WorthFuzzing": false
}

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.

Target architecture: amd64

For your convenience, here is the diff of the changes:
commit d7746e032ed8bafeb18ebc38e08f8b7f2a55f78a
Author: syz-cluster <triage@syzkaller.com>
Date:   Sat Sep 5 12:56:10 2026 +0000

    syz-cluster: applied patch under review

diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index a50540ef6521c..1583150241c88 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -1340,6 +1340,12 @@ static int do_skeleton(int argc, char **argv)
 	}
 	bpf_object__for_each_program(prog, obj) {
 		prog_cnt++;
+
+		if (use_loader && !bpf_program__autoload(prog)) {
+			p_err("program '%s' is marked as non-autoload, which is not supported for light skeletons",
+			      bpf_program__name(prog));
+			return -1;
+		}
 	}
 
 	get_header_guard(header_guard, obj_name, "SKEL_H");
diff --git a/tools/testing/selftests/bpf/prog_tests/global_data_init.c b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
index 7c539cbcf3a1e..dbb7de534f7de 100644
--- a/tools/testing/selftests/bpf/prog_tests/global_data_init.c
+++ b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
@@ -3,6 +3,7 @@
 #include "bpf/libbpf_internal.h"
 #include "test_global_percpu_data.skel.h"
 #include "test_global_percpu_data.lskel.h"
+#include "test_global_percpu_data_failure.skel.h"
 
 void test_global_data_init(void)
 {
@@ -372,7 +373,7 @@ static void test_global_percpu_data_rdonly_direct_write(void)
 
 static void test_global_percpu_data_verifier_log(void)
 {
-	RUN_TESTS(test_global_percpu_data);
+	RUN_TESTS(test_global_percpu_data_failure);
 }
 
 static void test_global_percpu_data_iter(void)
diff --git a/tools/testing/selftests/bpf/progs/test_global_percpu_data.c b/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
index 2765cd46e9af0..bc748df4a6cc8 100644
--- a/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
+++ b/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
@@ -42,29 +42,6 @@ int update_percpu_data(void *ctx)
 	return 0;
 }
 
-static const char fmt[] SEC(".percpu.fmt") = "data %d\n";
-
-SEC("?kprobe")
-__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
-int verifier_strncmp(void *ctx)
-{
-	return bpf_strncmp("test", 5, fmt);
-}
-
-SEC("?kprobe")
-__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
-int verifier_snprintf(void *ctx)
-{
-	u64 args[] = { data };
-	char buf[128];
-	int len;
-
-	len = bpf_snprintf(buf, sizeof(buf), fmt, args, sizeof(args));
-	if (len > 0)
-		bpf_printk("snprintf: %s\n", buf);
-	return 0;
-}
-
 volatile const __u32 num_cpus = 0;
 volatile const int num_off;
 volatile const int elem_sz;
diff --git a/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c b/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c
new file mode 100644
index 0000000000000..3a823acb42d74
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+int data SEC(".percpu") = -1;
+static const char fmt[] SEC(".percpu.fmt") = "data %d\n";
+
+SEC("?kprobe")
+__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
+int verifier_strncmp(void *ctx)
+{
+	return bpf_strncmp("test", 5, fmt);
+}
+
+SEC("?kprobe")
+__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
+int verifier_snprintf(void *ctx)
+{
+	u64 args[] = { data };
+	char buf[128];
+	int len;
+
+	len = bpf_snprintf(buf, sizeof(buf), fmt, args, sizeof(args));
+	if (len > 0)
+		bpf_printk("snprintf: %s\n", buf);
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";

gemini-3.7-flash

null

null

							input: 4195
							output: 64
							thoughts: 518
						

**WorthFuzzing Decision for this Patch**

Okay, let's break this down. The diff affects these files: `tools/bpf/bpftool/gen.c`, `tools/testing/selftests/bpf/prog_tests/global_data_init.c`, `tools/testing/selftests/bpf/progs/test_global_percpu_data.c`, and `tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c`.

Now, according to the "WHEN TO RETURN WorthFuzzing=false" criteria (Section 2), we should *only* return `WorthFuzzing=false` if *all* the modified code falls into one or more of these categories: non-kernel, non-executable changes that don't affect the kernel image (vmlinux) or modules. Specifically, that means user-space stuff like tools, self-tests, samples, or scripts.

Looking at these files, it's pretty clear: they're all in `tools/`, specifically `tools/bpf/bpftool` and `tools/testing/selftests/bpf/`. None of them are touching any core kernel code or anything that would impact the built kernel image, vmlinux, or any modules.

I've double-checked the list of modified files to be completely sure. I could verify via `git status`/`git diff`, but the prompt already lists all the files so this seems unnecessary.

Therefore, this is a straightforward case. I'm going to call `set-results` with:
- `EnableConfigs: [] or null`
- `FocusSymbols: [] or null`
- `Reasoning: Changes strictly to userspace tools (tools/bpf/bpftool) and selftests (tools/testing/selftests/bpf), with no changes to the kernel image or modules.`
- `WorthFuzzing: false.`

{
  "EnableConfigs": [],
  "FocusSymbols": [],
  "Reasoning": "The patch only modifies user-space tools (bpftool) and BPF selftests under tools/, with no changes affecting the compiled kernel image or modules.",
  "WorthFuzzing": false
}

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch only modifies user-space tools (bpftool) and BPF selftests under tools/, with no changes affecting the compiled kernel image or modules.",
  "WorthFuzzing": false
}

{
  "WorthFuzzing": false
}

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