AI Trajectory

null

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_assoc_bh_rcv",
    "sctp_endpoint_bh_rcv"
  ],
  "Reasoning": "The patch fixes a potential null pointer dereference in SCTP chunk processing by checking the result of skb_clone. This is a functional change in the core SCTP logic that should be fuzzed.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit 9936f0a219f591be9e1b3e971938f88095cccf6d\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Tue Jul 21 15:15:44 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/net/sctp/associola.c b/net/sctp/associola.c\nindex 62d3cc155809c7..7741f982e36813 100644\n--- a/net/sctp/associola.c\n+++ b/net/sctp/associola.c\n@@ -999,6 +999,8 @@ static void sctp_assoc_bh_rcv(struct work_struct *work)\n \t\t\tif (next_hdr-\u003etype == SCTP_CID_COOKIE_ECHO) {\n \t\t\t\tchunk-\u003eauth_chunk = skb_clone(chunk-\u003eskb,\n \t\t\t\t\t\t\t      GFP_ATOMIC);\n+\t\t\t\tif (!chunk-\u003eauth_chunk)\n+\t\t\t\t\tbreak;\n \t\t\t\tchunk-\u003eauth = 1;\n \t\t\t\tcontinue;\n \t\t\t}\ndiff --git a/net/sctp/endpointola.c b/net/sctp/endpointola.c\nindex dfb1719275dba7..9675370a46da55 100644\n--- a/net/sctp/endpointola.c\n+++ b/net/sctp/endpointola.c\n@@ -368,6 +368,8 @@ static void sctp_endpoint_bh_rcv(struct work_struct *work)\n \t\t\tif (next_hdr-\u003etype == SCTP_CID_COOKIE_ECHO) {\n \t\t\t\tchunk-\u003eauth_chunk = skb_clone(chunk-\u003eskb,\n \t\t\t\t\t\t\t\tGFP_ATOMIC);\n+\t\t\t\tif (!chunk-\u003eauth_chunk)\n+\t\t\t\t\tbreak;\n \t\t\t\tchunk-\u003eauth = 1;\n \t\t\t\tcontinue;\n \t\t\t}\n"
}

best-expensive

null

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_assoc_bh_rcv",
    "sctp_endpoint_bh_rcv"
  ],
  "Reasoning": "The patch fixes a potential null pointer dereference in SCTP chunk processing by checking the result of skb_clone. This is a functional change in the core SCTP logic that should be fuzzed.",
  "WorthFuzzing": true
}

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 9936f0a219f591be9e1b3e971938f88095cccf6d
Author: syz-cluster <triage@syzkaller.com>
Date:   Tue Jul 21 15:15:44 2026 +0000

    syz-cluster: applied patch under review

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index 62d3cc155809c7..7741f982e36813 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -999,6 +999,8 @@ static void sctp_assoc_bh_rcv(struct work_struct *work)
 			if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
 				chunk->auth_chunk = skb_clone(chunk->skb,
 							      GFP_ATOMIC);
+				if (!chunk->auth_chunk)
+					break;
 				chunk->auth = 1;
 				continue;
 			}
diff --git a/net/sctp/endpointola.c b/net/sctp/endpointola.c
index dfb1719275dba7..9675370a46da55 100644
--- a/net/sctp/endpointola.c
+++ b/net/sctp/endpointola.c
@@ -368,6 +368,8 @@ static void sctp_endpoint_bh_rcv(struct work_struct *work)
 			if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
 				chunk->auth_chunk = skb_clone(chunk->skb,
 								GFP_ATOMIC);
+				if (!chunk->auth_chunk)
+					break;
 				chunk->auth = 1;
 				continue;
 			}

gemini-3.1-pro-preview

null

null

							input: 2111
							output: 34
							thoughts: 174
						

**Analyzing a Patch and Preparing for Fuzzing**

Okay, so I'm looking at this patch and it's touching `net/sctp/associola.c` and `net/sctp/endpointola.c`. It looks like they've added a `!chunk->auth_chunk` check after a `skb_clone` call within the `sctp_assoc_bh_rcv` and `sctp_endpoint_bh_rcv` functions. Hmm, so if `skb_clone` fails, it exits the loop. Interesting. Definitely worth investigating the rationale here.

These functions, `sctp_assoc_bh_rcv` and `sctp_endpoint_bh_rcv`, are clearly crucial to the SCTP protocol implementation. Given this change, and the fact they handle incoming messages, they scream "fuzz me!". That's where I need to focus my efforts.

Now, let me just quickly confirm the SCTP config option. It's usually `CONFIG_IP_SCTP`, but it's always good to verify that assumption before diving into the fuzzing configuration.

{
  "Expression": "config IP_SCTP",
  "PathPrefix": "net/sctp/Kconfig"
}

{
  "Output": "net/sctp/Kconfig-5-\nnet/sctp/Kconfig:6:menuconfig IP_SCTP\nnet/sctp/Kconfig-7-\ttristate \"The SCTP Protocol\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 2632
							output: 72
							thoughts: 54
						

**Analyzing SCTP Configuration**

Okay, so I'm pretty sure `IP_SCTP` is the key configuration here. Now, I need to pinpoint the relevant functions within the system. Let's see... it looks like `sctp_assoc_bh_rcv` and `sctp_endpoint_bh_rcv` are the likely candidates for handling the incoming data. But before I dive any deeper, I should double check. I need to make sure I'm not missing any other related configurations that might also be at play here. Let's explore.

{
  "Expression": "sctp_assoc_bh_rcv",
  "PathPrefix": "net/sctp/"
}

{
  "Output": "net/sctp/associola.c=43=static void sctp_select_active_and_retran_path(struct sctp_association *asoc);\nnet/sctp/associola.c:44:static void sctp_assoc_bh_rcv(struct work_struct *work);\nnet/sctp/associola.c-45-static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc);\n--\nnet/sctp/associola.c=51=static struct sctp_association *sctp_association_init(\n--\nnet/sctp/associola.c-224-\tsctp_inq_init(\u0026asoc-\u003ebase.inqueue);\nnet/sctp/associola.c:225:\tsctp_inq_set_th_handler(\u0026asoc-\u003ebase.inqueue, sctp_assoc_bh_rcv);\nnet/sctp/associola.c-226-\n--\nnet/sctp/associola.c=905=struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,\n--\nnet/sctp/associola.c-960-/* Do delayed input processing.  This is scheduled by sctp_rcv(). */\nnet/sctp/associola.c:961:static void sctp_assoc_bh_rcv(struct work_struct *work)\nnet/sctp/associola.c-962-{\n"
}

{
  "Expression": "sctp_endpoint_bh_rcv",
  "PathPrefix": "net/sctp/"
}

{
  "Output": "net/sctp/endpointola.c-35-/* Forward declarations for internal helpers. */\nnet/sctp/endpointola.c:36:static void sctp_endpoint_bh_rcv(struct work_struct *work);\nnet/sctp/endpointola.c-37-\n--\nnet/sctp/endpointola.c=50=static struct sctp_endpoint *sctp_endpoint_init(struct sctp_endpoint *ep,\n--\nnet/sctp/endpointola.c-79-\t/* Set its top-half handler */\nnet/sctp/endpointola.c:80:\tsctp_inq_set_th_handler(\u0026ep-\u003ebase.inqueue, sctp_endpoint_bh_rcv);\nnet/sctp/endpointola.c-81-\n--\nnet/sctp/endpointola.c=302=bool sctp_endpoint_is_peeled_off(struct sctp_endpoint *ep,\n--\nnet/sctp/endpointola.c-325- */\nnet/sctp/endpointola.c:326:static void sctp_endpoint_bh_rcv(struct work_struct *work)\nnet/sctp/endpointola.c-327-{\n"
}

gemini-3.1-pro-preview

null

null

							input: 3605
							output: 105
							thoughts: 123
						

**Analyzing a SCTP Vulnerability Patch**

Okay, so I'm looking at this patch and immediately, my expert eye hones in on a potential null pointer dereference issue within the SCTP code. The core of the change is adding a check for `!chunk->auth_chunk` after the `skb_clone` function call in both `sctp_assoc_bh_rcv` and `sctp_endpoint_bh_rcv`. Basically, if `skb_clone` fails, the code now correctly breaks out of the processing loop. This is fundamentally a functional change designed to prevent a crash, which is good.

Given that this patch addresses a potential memory access vulnerability, my next thought is, "This warrants fuzzing attention." I want to know, thoroughly, how robust this fix is. The prime candidates for fuzzing focus will be, naturally, `sctp_assoc_bh_rcv` and `sctp_endpoint_bh_rcv`, especially since the patch touches them directly.

The configuration required is `IP_SCTP`, which is as expected, so the testing configuration is straightforward and shouldn't present an obstacle. It's a relatively focused patch with a clear goal, so I'm optimistic about its impact.

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_assoc_bh_rcv",
    "sctp_endpoint_bh_rcv"
  ],
  "Reasoning": "The patch fixes a potential null pointer dereference in SCTP chunk processing by checking the result of skb_clone. This is a functional change in the core SCTP logic that should be fuzzed.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_assoc_bh_rcv",
    "sctp_endpoint_bh_rcv"
  ],
  "Reasoning": "The patch fixes a potential null pointer dereference in SCTP chunk processing by checking the result of skb_clone. This is a functional change in the core SCTP logic that should be fuzzed.",
  "WorthFuzzing": true
}