AI Trajectory

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch only modifies a BPF program used internally by the user-space `perf` tool (`tools/perf/`). This code is not part of the core kernel image and is not reachable via standard kernel fuzzing, as syzkaller fuzzes the kernel via syscalls and does not execute user-space utilities like `perf`.",
  "WorthFuzzing": false
}

null

{
  "PatchDiff": "commit 69603fcaa5095647859508963700021e85a707fe\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Mon Jul 6 17:51:03 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c b/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c\nindex 2a6e61864ee015..215516df5d2a38 100644\n--- a/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c\n+++ b/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c\n@@ -429,15 +429,88 @@ static bool pid_filter__has(struct pids_filtered *pids, pid_t pid)\n \treturn bpf_map_lookup_elem(pids, \u0026pid) != NULL;\n }\n \n+u64 ZERO = 0;\n+\n+/*\n+ * Determine what type of argument and how many bytes to read from user space, using the\n+ * value in the beauty_map. This is the relation of parameter type and its corresponding\n+ * value in the beauty map, and how many bytes we read eventually:\n+ *\n+ * string: 1\t\t\t      -\u003e size of string\n+ * struct: size of struct\t      -\u003e size of struct\n+ * buffer: -1 * (index of paired len) -\u003e value of paired len (maximum: TRACE_AUG_MAX_BUF)\n+ */\n+static inline int augment_arg(struct syscall_enter_args *args, int i,\n+\t\t\t      unsigned int *beauty_map,\n+\t\t\t      struct beauty_payload_enter *payload, u64 offset)\n+{\n+\tint index, size, value_size = sizeof(struct augmented_arg) - offsetof(struct augmented_arg, value);\n+\tstruct augmented_arg *payload_offset;\n+\ts64 aug_size;\n+\tbool augmented;\n+\tvoid *arg;\n+\n+\targ = (void *)args-\u003eargs[i];\n+\taugmented = false;\n+\tsize = beauty_map[i];\n+\taug_size = size; /* size of the augmented data read from user space */\n+\n+\tif (size == 0 || arg == NULL)\n+\t\treturn 0;\n+\n+\t/* bounds check for the verifier */\n+\tif (offset \u003e sizeof(payload-\u003eaug_args) - sizeof(payload-\u003eaug_args[0]))\n+\t\treturn -1;\n+\tbarrier_var(offset);\n+\tpayload_offset = (struct augmented_arg *)((void *)\u0026payload-\u003eaug_args + offset);\n+\n+\tif (size == 1) { /* string */\n+\t\taug_size = bpf_probe_read_user_str(payload_offset-\u003evalue, value_size, arg);\n+\t\t/* minimum of 0 to pass the verifier */\n+\t\tif (aug_size \u003c 0)\n+\t\t\taug_size = 0;\n+\n+\t\taugmented = true;\n+\t} else if (size \u003e 0 \u0026\u0026 size \u003c= value_size) { /* struct */\n+\t\tif (!bpf_probe_read_user(payload_offset-\u003evalue, size, arg))\n+\t\t\taugmented = true;\n+\t} else if (size \u003c 0 \u0026\u0026 size \u003e= -6) { /* buffer */\n+\t\tindex = -(size + 1);\n+\t\tbarrier_var(index); // Prevent clang (noticed with v18) from removing the \u0026= 7 trick.\n+\t\tindex \u0026= 7;\t    // Satisfy the bounds checking with the verifier in some kernels.\n+\t\taug_size = args-\u003eargs[index] \u003e TRACE_AUG_MAX_BUF ? TRACE_AUG_MAX_BUF : args-\u003eargs[index];\n+\n+\t\tif (aug_size \u003e 0) {\n+\t\t\tif (!bpf_probe_read_user(payload_offset-\u003evalue, aug_size, arg))\n+\t\t\t\taugmented = true;\n+\t\t}\n+\t}\n+\n+\t/* Augmented data size is limited to sizeof(augmented_arg-\u003eunnamed union with value field) */\n+\tif (aug_size \u003e value_size)\n+\t\taug_size = value_size;\n+\n+\t/* write data to payload */\n+\tif (augmented) {\n+\t\tint written = offsetof(struct augmented_arg, value) + aug_size;\n+\n+\t\tif (written \u003c 0 || written \u003e sizeof(struct augmented_arg))\n+\t\t\treturn -1;\n+\n+\t\tpayload_offset-\u003esize = aug_size;\n+\t\treturn written;\n+\t}\n+\n+\treturn 0;\n+}\n+\n static int augment_sys_enter(void *ctx, struct syscall_enter_args *args)\n {\n-\tbool augmented, do_output = false;\n-\tint zero = 0, index, value_size = sizeof(struct augmented_arg) - offsetof(struct augmented_arg, value);\n+\tbool do_output = false;\n+\tint i, zero = 0, written;\n \tu64 output = 0; /* has to be u64, otherwise it won't pass the verifier */\n-\ts64 aug_size, size;\n \tunsigned int nr, *beauty_map;\n \tstruct beauty_payload_enter *payload;\n-\tvoid *arg, *payload_offset;\n \n \t/* fall back to do predefined tail call */\n \tif (args == NULL)\n@@ -449,7 +522,6 @@ static int augment_sys_enter(void *ctx, struct syscall_enter_args *args)\n \n \t/* set up payload for output */\n \tpayload        = bpf_map_lookup_elem(\u0026beauty_payload_enter_map, \u0026zero);\n-\tpayload_offset = (void *)\u0026payload-\u003eaug_args;\n \n \tif (beauty_map == NULL || payload == NULL)\n \t\treturn 1;\n@@ -457,61 +529,30 @@ static int augment_sys_enter(void *ctx, struct syscall_enter_args *args)\n \t/* copy the sys_enter header, which has the syscall_nr */\n \t__builtin_memcpy(\u0026payload-\u003eargs, args, sizeof(struct syscall_enter_args));\n \n-\t/*\n-\t * Determine what type of argument and how many bytes to read from user space, using the\n-\t * value in the beauty_map. This is the relation of parameter type and its corresponding\n-\t * value in the beauty map, and how many bytes we read eventually:\n-\t *\n-\t * string: 1\t\t\t      -\u003e size of string\n-\t * struct: size of struct\t      -\u003e size of struct\n-\t * buffer: -1 * (index of paired len) -\u003e value of paired len (maximum: TRACE_AUG_MAX_BUF)\n-\t */\n-\tfor (int i = 0; i \u003c 6; i++) {\n-\t\targ = (void *)args-\u003eargs[i];\n-\t\taugmented = false;\n-\t\tsize = beauty_map[i];\n-\t\taug_size = size; /* size of the augmented data read from user space */\n-\n-\t\tif (size == 0 || arg == NULL)\n-\t\t\tcontinue;\n-\n-\t\tif (size == 1) { /* string */\n-\t\t\taug_size = bpf_probe_read_user_str(((struct augmented_arg *)payload_offset)-\u003evalue, value_size, arg);\n-\t\t\t/* minimum of 0 to pass the verifier */\n-\t\t\tif (aug_size \u003c 0)\n-\t\t\t\taug_size = 0;\n-\n-\t\t\taugmented = true;\n-\t\t} else if (size \u003e 0 \u0026\u0026 size \u003c= value_size) { /* struct */\n-\t\t\tif (!bpf_probe_read_user(((struct augmented_arg *)payload_offset)-\u003evalue, size, arg))\n-\t\t\t\taugmented = true;\n-\t\t} else if ((int)size \u003c 0 \u0026\u0026 size \u003e= -6) { /* buffer */\n-\t\t\tindex = -(size + 1);\n-\t\t\tbarrier_var(index); // Prevent clang (noticed with v18) from removing the \u0026= 7 trick.\n-\t\t\tindex \u0026= 7;\t    // Satisfy the bounds checking with the verifier in some kernels.\n-\t\t\taug_size = args-\u003eargs[index] \u003e TRACE_AUG_MAX_BUF ? TRACE_AUG_MAX_BUF : args-\u003eargs[index];\n-\n-\t\t\tif (aug_size \u003e 0) {\n-\t\t\t\tif (!bpf_probe_read_user(((struct augmented_arg *)payload_offset)-\u003evalue, aug_size, arg))\n-\t\t\t\t\taugmented = true;\n+\tif (bpf_ksym_exists(bpf_iter_num_new)) {\n+\t\tbpf_for(i, 0, 6) {\n+\t\t\twritten = augment_arg(args, i, beauty_map, payload, output);\n+\t\t\tif (written \u003c 0)\n+\t\t\t\treturn 1;\n+\t\t\tif (written \u003e 0) {\n+\t\t\t\toutput += written;\n+\t\t\t\t/*\n+\t\t\t\t * guide the verifier to forget range of `output`, which\n+\t\t\t\t * helps to prove convergence of the loop\n+\t\t\t\t */\n+\t\t\t\toutput += ZERO;\n+\t\t\t\tdo_output = true;\n \t\t\t}\n \t\t}\n-\n-\t\t/* Augmented data size is limited to sizeof(augmented_arg-\u003eunnamed union with value field) */\n-\t\tif (aug_size \u003e value_size)\n-\t\t\taug_size = value_size;\n-\n-\t\t/* write data to payload */\n-\t\tif (augmented) {\n-\t\t\tint written = offsetof(struct augmented_arg, value) + aug_size;\n-\n-\t\t\tif (written \u003c 0 || written \u003e sizeof(struct augmented_arg))\n+\t} else {\n+\t\tfor (i = 0; i \u003c 6; i++) {\n+\t\t\twritten = augment_arg(args, i, beauty_map, payload, output);\n+\t\t\tif (written \u003c 0)\n \t\t\t\treturn 1;\n-\n-\t\t\t((struct augmented_arg *)payload_offset)-\u003esize = aug_size;\n-\t\t\toutput += written;\n-\t\t\tpayload_offset += written;\n-\t\t\tdo_output = true;\n+\t\t\tif (written \u003e 0) {\n+\t\t\t\toutput += written;\n+\t\t\t\tdo_output = true;\n+\t\t\t}\n \t\t}\n \t}\n \n"
}

gemini-3.1-pro-preview

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch only modifies a BPF program used internally by the user-space `perf` tool (`tools/perf/`). This code is not part of the core kernel image and is not reachable via standard kernel fuzzing, as syzkaller fuzzes the kernel via syscalls and does not execute user-space utilities like `perf`.",
  "WorthFuzzing": false
}

You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).

If it modifies reachable core kernel logic, drivers, or architectures, use your code search
tools to verify the code can be executed, then return WorthFuzzing=true.

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Do not list too generic configs (we already have them enabled). Only list those that
   specifically cover the modified code. List them in the EnableConfigs output array,
   and DO NOT add a '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.

For your convenience, here is the diff of the changes:
commit 69603fcaa5095647859508963700021e85a707fe
Author: syz-cluster <triage@syzkaller.com>
Date:   Mon Jul 6 17:51:03 2026 +0000

    syz-cluster: applied patch under review

diff --git a/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c b/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c
index 2a6e61864ee015..215516df5d2a38 100644
--- a/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c
+++ b/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c
@@ -429,15 +429,88 @@ static bool pid_filter__has(struct pids_filtered *pids, pid_t pid)
 	return bpf_map_lookup_elem(pids, &pid) != NULL;
 }
 
+u64 ZERO = 0;
+
+/*
+ * Determine what type of argument and how many bytes to read from user space, using the
+ * value in the beauty_map. This is the relation of parameter type and its corresponding
+ * value in the beauty map, and how many bytes we read eventually:
+ *
+ * string: 1			      -> size of string
+ * struct: size of struct	      -> size of struct
+ * buffer: -1 * (index of paired len) -> value of paired len (maximum: TRACE_AUG_MAX_BUF)
+ */
+static inline int augment_arg(struct syscall_enter_args *args, int i,
+			      unsigned int *beauty_map,
+			      struct beauty_payload_enter *payload, u64 offset)
+{
+	int index, size, value_size = sizeof(struct augmented_arg) - offsetof(struct augmented_arg, value);
+	struct augmented_arg *payload_offset;
+	s64 aug_size;
+	bool augmented;
+	void *arg;
+
+	arg = (void *)args->args[i];
+	augmented = false;
+	size = beauty_map[i];
+	aug_size = size; /* size of the augmented data read from user space */
+
+	if (size == 0 || arg == NULL)
+		return 0;
+
+	/* bounds check for the verifier */
+	if (offset > sizeof(payload->aug_args) - sizeof(payload->aug_args[0]))
+		return -1;
+	barrier_var(offset);
+	payload_offset = (struct augmented_arg *)((void *)&payload->aug_args + offset);
+
+	if (size == 1) { /* string */
+		aug_size = bpf_probe_read_user_str(payload_offset->value, value_size, arg);
+		/* minimum of 0 to pass the verifier */
+		if (aug_size < 0)
+			aug_size = 0;
+
+		augmented = true;
+	} else if (size > 0 && size <= value_size) { /* struct */
+		if (!bpf_probe_read_user(payload_offset->value, size, arg))
+			augmented = true;
+	} else if (size < 0 && size >= -6) { /* buffer */
+		index = -(size + 1);
+		barrier_var(index); // Prevent clang (noticed with v18) from removing the &= 7 trick.
+		index &= 7;	    // Satisfy the bounds checking with the verifier in some kernels.
+		aug_size = args->args[index] > TRACE_AUG_MAX_BUF ? TRACE_AUG_MAX_BUF : args->args[index];
+
+		if (aug_size > 0) {
+			if (!bpf_probe_read_user(payload_offset->value, aug_size, arg))
+				augmented = true;
+		}
+	}
+
+	/* Augmented data size is limited to sizeof(augmented_arg->unnamed union with value field) */
+	if (aug_size > value_size)
+		aug_size = value_size;
+
+	/* write data to payload */
+	if (augmented) {
+		int written = offsetof(struct augmented_arg, value) + aug_size;
+
+		if (written < 0 || written > sizeof(struct augmented_arg))
+			return -1;
+
+		payload_offset->size = aug_size;
+		return written;
+	}
+
+	return 0;
+}
+
 static int augment_sys_enter(void *ctx, struct syscall_enter_args *args)
 {
-	bool augmented, do_output = false;
-	int zero = 0, index, value_size = sizeof(struct augmented_arg) - offsetof(struct augmented_arg, value);
+	bool do_output = false;
+	int i, zero = 0, written;
 	u64 output = 0; /* has to be u64, otherwise it won't pass the verifier */
-	s64 aug_size, size;
 	unsigned int nr, *beauty_map;
 	struct beauty_payload_enter *payload;
-	void *arg, *payload_offset;
 
 	/* fall back to do predefined tail call */
 	if (args == NULL)
@@ -449,7 +522,6 @@ static int augment_sys_enter(void *ctx, struct syscall_enter_args *args)
 
 	/* set up payload for output */
 	payload        = bpf_map_lookup_elem(&beauty_payload_enter_map, &zero);
-	payload_offset = (void *)&payload->aug_args;
 
 	if (beauty_map == NULL || payload == NULL)
 		return 1;
@@ -457,61 +529,30 @@ static int augment_sys_enter(void *ctx, struct syscall_enter_args *args)
 	/* copy the sys_enter header, which has the syscall_nr */
 	__builtin_memcpy(&payload->args, args, sizeof(struct syscall_enter_args));
 
-	/*
-	 * Determine what type of argument and how many bytes to read from user space, using the
-	 * value in the beauty_map. This is the relation of parameter type and its corresponding
-	 * value in the beauty map, and how many bytes we read eventually:
-	 *
-	 * string: 1			      -> size of string
-	 * struct: size of struct	      -> size of struct
-	 * buffer: -1 * (index of paired len) -> value of paired len (maximum: TRACE_AUG_MAX_BUF)
-	 */
-	for (int i = 0; i < 6; i++) {
-		arg = (void *)args->args[i];
-		augmented = false;
-		size = beauty_map[i];
-		aug_size = size; /* size of the augmented data read from user space */
-
-		if (size == 0 || arg == NULL)
-			continue;
-
-		if (size == 1) { /* string */
-			aug_size = bpf_probe_read_user_str(((struct augmented_arg *)payload_offset)->value, value_size, arg);
-			/* minimum of 0 to pass the verifier */
-			if (aug_size < 0)
-				aug_size = 0;
-
-			augmented = true;
-		} else if (size > 0 && size <= value_size) { /* struct */
-			if (!bpf_probe_read_user(((struct augmented_arg *)payload_offset)->value, size, arg))
-				augmented = true;
-		} else if ((int)size < 0 && size >= -6) { /* buffer */
-			index = -(size + 1);
-			barrier_var(index); // Prevent clang (noticed with v18) from removing the &= 7 trick.
-			index &= 7;	    // Satisfy the bounds checking with the verifier in some kernels.
-			aug_size = args->args[index] > TRACE_AUG_MAX_BUF ? TRACE_AUG_MAX_BUF : args->args[index];
-
-			if (aug_size > 0) {
-				if (!bpf_probe_read_user(((struct augmented_arg *)payload_offset)->value, aug_size, arg))
-					augmented = true;
+	if (bpf_ksym_exists(bpf_iter_num_new)) {
+		bpf_for(i, 0, 6) {
+			written = augment_arg(args, i, beauty_map, payload, output);
+			if (written < 0)
+				return 1;
+			if (written > 0) {
+				output += written;
+				/*
+				 * guide the verifier to forget range of `output`, which
+				 * helps to prove convergence of the loop
+				 */
+				output += ZERO;
+				do_output = true;
 			}
 		}
-
-		/* Augmented data size is limited to sizeof(augmented_arg->unnamed union with value field) */
-		if (aug_size > value_size)
-			aug_size = value_size;
-
-		/* write data to payload */
-		if (augmented) {
-			int written = offsetof(struct augmented_arg, value) + aug_size;
-
-			if (written < 0 || written > sizeof(struct augmented_arg))
+	} else {
+		for (i = 0; i < 6; i++) {
+			written = augment_arg(args, i, beauty_map, payload, output);
+			if (written < 0)
 				return 1;
-
-			((struct augmented_arg *)payload_offset)->size = aug_size;
-			output += written;
-			payload_offset += written;
-			do_output = true;
+			if (written > 0) {
+				output += written;
+				do_output = true;
+			}
 		}
 	}
 

gemini-3.1-pro-preview

null

null

							input: 4077
							output: 99
							thoughts: 750
						

**Analysis of the `tools/perf` BPF Patch**

Okay, so I'm looking at this patch and my initial thought is, it's modifying `tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c`. This immediately makes me think, "BPF program!" and that this is used by the `perf` tool. Now, `perf` is user-space, although it does use BPF skeletons and loads programs into the kernel. The key distinction here is that this specific BPF code, while kernel-bound when running `perf`, *isn't* part of the core kernel image itself. It's source code within the `perf` tool.

My internal checklist immediately kicks in. Is this something worth fuzzing? The usual rules apply: Documentation changes, comments, decorative logging... that's a no-go. But I also need to think specifically about syzkaller. Does this patch change something that is touched by syzkaller?

This is where it gets interesting.  Syzkaller focuses on the *kernel*.  While syzkaller *can* fuzz BPF programs, it doesn't do so by running `perf` or by using BPF code provided with it. Syzkaller's purpose is to fuzz the kernel via syscalls. So, the question becomes, does this patch modify something that can be reached by a syzkaller syscall?

Let me step back and make sure. `tools/perf` is a user-space tool. Syzkaller doesn't directly run user-space tools. It generates its own BPF programs.  It doesn't use the BPF code provided with the `perf` tool. So, the code within this patch won't be executed directly by syzkaller.

And what does this particular patch actually *do*? It's refactoring `augment_sys_enter` using `bpf_for`. Okay, BPF iterators, extracting `augment_arg`.  It doesn't seem like the core kernel code changes.

So, I need to check to be sure... I'm confident syzkaller is not going to fuzz `tools/perf`. I need to ensure that this isn't touching a kernel interface directly.  I confirm that the diff is *only* within `tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c`. This confirms it's a BPF program for `perf trace`.  Since it's part of the `perf` tool, and it's not part of the kernel image that syzkaller fuzzes. Therefore, this change is not going to be fuzzed by syzkaller.

Okay, my conclusion: `WorthFuzzing=false`. The reasoning is that the change is limited to a BPF program used internally by the user-space `perf` tool. Syzkaller focuses on fuzzing the kernel, and this change is not part of the kernel's core image and isn't accessible via the syscalls that syzkaller utilizes.

{
  "EnableConfigs": [],
  "FocusSymbols": [],
  "Reasoning": "The patch only modifies a BPF program used internally by the user-space `perf` tool (`tools/perf/`). This code is not part of the core kernel image and is not reachable via standard kernel fuzzing, as syzkaller fuzzes the kernel via syscalls and does not execute user-space utilities like `perf`.",
  "WorthFuzzing": false
}

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch only modifies a BPF program used internally by the user-space `perf` tool (`tools/perf/`). This code is not part of the core kernel image and is not reachable via standard kernel fuzzing, as syzkaller fuzzes the kernel via syscalls and does not execute user-space utilities like `perf`.",
  "WorthFuzzing": false
}