AI Trajectory

null

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_sf_do_6_3_3_rtx"
  ],
  "Reasoning": "The patch modifies the condition for handling T3-rtx timer expirations in SCTP when the peer has announced a zero window. This is a functional change in the core SCTP state machine logic and should be fuzzed to ensure it doesn't introduce regressions or unexpected behavior.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit eab396d4ef4d633b16e73e7049c567d4a29b85f5\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Fri Jul 31 15:44:26 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c\nindex 708fa07d5fffc..b01db33bbc360 100644\n--- a/net/sctp/sm_statefuns.c\n+++ b/net/sctp/sm_statefuns.c\n@@ -5842,8 +5842,7 @@ enum sctp_disposition sctp_sf_do_6_3_3_rtx(struct net *net,\n \tSCTP_INC_STATS(net, SCTP_MIB_T3_RTX_EXPIREDS);\n \n \tif (asoc-\u003eoverall_error_count \u003e= asoc-\u003emax_retrans) {\n-\t\tif (asoc-\u003epeer.zero_window_announced \u0026\u0026\n-\t\t    asoc-\u003estate == SCTP_STATE_SHUTDOWN_PENDING) {\n+\t\tif (asoc-\u003epeer.zero_window_announced) {\n \t\t\t/*\n \t\t\t * We are here likely because the receiver had its rwnd\n \t\t\t * closed for a while and we have not been able to\n"
}

best-expensive

null

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_sf_do_6_3_3_rtx"
  ],
  "Reasoning": "The patch modifies the condition for handling T3-rtx timer expirations in SCTP when the peer has announced a zero window. This is a functional change in the core SCTP state machine logic and should be fuzzed to ensure it doesn't introduce regressions or unexpected behavior.",
  "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).
- Code in vendor-specific PCIe switch, SmartNIC, or GPU drivers (e.g., mlxsw, pds_core, qed,
  ionic, amdgpu) that require physical PCIe hardware cards not emulated in standard QEMU.
- Driver .remove, .shutdown, or pci_unregister_driver teardown callbacks (e.g., igb_remove)
  that are executed only during PCI hot-unplug or sysfs driver unbind operations.

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.
   Prefer non-static, non-inlined API entrypoint functions over internal static helper functions
   (which are inlined by the compiler and do not have distinct symbol addresses).
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.
   Also check "depends on" lines in Kconfig to include any non-standard parent subsystem configs
   needed for Kbuild to compile the code statically into vmlinux. 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 eab396d4ef4d633b16e73e7049c567d4a29b85f5
Author: syz-cluster <triage@syzkaller.com>
Date:   Fri Jul 31 15:44:26 2026 +0000

    syz-cluster: applied patch under review

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index 708fa07d5fffc..b01db33bbc360 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -5842,8 +5842,7 @@ enum sctp_disposition sctp_sf_do_6_3_3_rtx(struct net *net,
 	SCTP_INC_STATS(net, SCTP_MIB_T3_RTX_EXPIREDS);
 
 	if (asoc->overall_error_count >= asoc->max_retrans) {
-		if (asoc->peer.zero_window_announced &&
-		    asoc->state == SCTP_STATE_SHUTDOWN_PENDING) {
+		if (asoc->peer.zero_window_announced) {
 			/*
 			 * We are here likely because the receiver had its rwnd
 			 * closed for a while and we have not been able to

gemini-3.1-pro-preview

null

null

							input: 2128
							output: 49
							thoughts: 183
						

**Analyzing a SCTP Patch**

Okay, so I'm looking at this patch for `net/sctp/sm_statefuns.c`. The core of the change appears to be in how retransmissions are handled, specifically within the `sctp_sf_do_6_3_3_rtx` function. They've removed `asoc->state == SCTP_STATE_SHUTDOWN_PENDING` from the conditional check. Interesting. That's a definite functional change; it's going to alter the retransmission behavior under certain circumstances.

I need to understand the implications, so I'm going to quickly review the surrounding code in `net/sctp/sm_statefuns.c`. The context of `sctp_sf_do_6_3_3_rtx` is critical here. I want to see *why* they removed that state check. Are they trying to optimize something? Fixing a subtle bug? Or are they altering shutdown behavior under a zero-window condition? I need to get a clear picture of the whole state machine function to properly assess this change.

{
  "Expression": "sctp_sf_do_6_3_3_rtx",
  "PathPrefix": "net/sctp/sm_statefuns.c"
}

{
  "Output": "net/sctp/sm_statefuns.c=5805=enum sctp_disposition sctp_sf_ignore_other(struct net *net,\n--\nnet/sctp/sm_statefuns.c-5832- */\nnet/sctp/sm_statefuns.c:5833:enum sctp_disposition sctp_sf_do_6_3_3_rtx(struct net *net,\nnet/sctp/sm_statefuns.c-5834-\t\t\t\t\t   const struct sctp_endpoint *ep,\n"
}

gemini-3.1-pro-preview

null

null

							input: 2760
							output: 34
							thoughts: 50
						

Okay, here's my take on those thoughts, framed as my own:

**Analyzing an SCTP T3-Rtx Timer Expiration**

Alright, so I'm looking at the `sctp_sf_do_6_3_3_rtx` function – that's a key SCTP state function, specifically designed to deal with the expiration of the T3-rtx timer. My immediate instinct is to understand the context. What's the SCTP configuration like? The timer's going off, so something's clearly amiss. Let's delve into the config parameters, especially those related to retransmission strategies and timeout values. I need to figure out *why* this timer expired and what the system is going to do about it. The goal is a clear understanding of the situation so that I can accurately debug.

{
  "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: 3087
							output: 49
							thoughts: 49
						

Okay, let's break this down.

**Analyzing the SCTP Retransmission Function**

Right, so the configuration in question is `IP_SCTP`. Got it. Now, I'm looking at `sctp_sf_do_6_3_3_rtx`. My initial thought is, this seems to be a state function, based on the naming convention. The next logical step is to quickly determine if it's declared `static`. That's a crucial piece of information for understanding its scope and potential interactions within the SCTP stack. Is this function localized, or visible globally? That is my immediate question. I need to clarify that before I can determine how this function functions.

{
  "Expression": "enum sctp_disposition sctp_sf_do_6_3_3_rtx",
  "PathPrefix": "net/sctp/"
}

{
  "Output": "net/sctp/sm_statefuns.c=5805=enum sctp_disposition sctp_sf_ignore_other(struct net *net,\n--\nnet/sctp/sm_statefuns.c-5832- */\nnet/sctp/sm_statefuns.c:5833:enum sctp_disposition sctp_sf_do_6_3_3_rtx(struct net *net,\nnet/sctp/sm_statefuns.c-5834-\t\t\t\t\t   const struct sctp_endpoint *ep,\n"
}

gemini-3.1-pro-preview

null

null

							input: 3493
							output: 44
							thoughts: 13
						

Okay, I'm ready to summarize my thought process. Here's how I'm approaching it:

**Verifying Declaration in a Header**

Alright, the objective is pretty straightforward. I'm focusing on determining whether a specific element or concept is explicitly defined or declared within a header file. That's the core question: is there a header involved, and if so, does it have the necessary declaration? I need to analyze the surrounding context, and code where possible to see if a header is present and the declaration exists within it. It's a fundamental step, often essential for understanding the scope, dependencies, and proper usage of something in a larger system or codebase.

{
  "Expression": "sctp_sf_do_6_3_3_rtx",
  "PathPrefix": "include/net/sctp/"
}

{
  "Output": "include/net/sctp/sm.h=149=sctp_state_fn_t sctp_sf_cookie_wait_icmp_abort;\n--\ninclude/net/sctp/sm.h-151-/* Prototypes for timeout event state functions.  */\ninclude/net/sctp/sm.h:152:sctp_state_fn_t sctp_sf_do_6_3_3_rtx;\ninclude/net/sctp/sm.h-153-sctp_state_fn_t sctp_sf_send_reconf;\n"
}

gemini-3.1-pro-preview

null

null

							input: 3853
							output: 34
							thoughts: 110
						

**Analyzing the SCTP State Function**

Okay, so I see `sctp_sf_do_6_3_3_rtx` is defined as `sctp_state_fn_t` in `include/net/sctp/sm.h`. Excellent, it's a non-static function, which means it should be directly usable as a focus symbol for further analysis. This is good; gives me a nice, clean entry point.

Now, before I dig in too deep, let's just confirm that there aren't any other critical configurations to be aware of. I'll quickly check for any dependencies, beyond the obvious `IP_SCTP` which, of course, I'd expect.

Right, let's navigate to `net/sctp/Kconfig` and scan through it. Want to make sure I'm not missing any enabling flags or hidden dependencies that might impact this specific function's behavior. Gotta be thorough.

{
  "File": "net/sctp/Kconfig",
  "FirstLine": 1,
  "LineCount": 20
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0-only\n   2:\t#\n   3:\t# SCTP configuration\n   4:\t#\n   5:\t\n   6:\tmenuconfig IP_SCTP\n   7:\t\ttristate \"The SCTP Protocol\"\n   8:\t\tdepends on INET\n   9:\t\tselect CRYPTO_LIB_SHA1\n  10:\t\tselect CRYPTO_LIB_SHA256\n  11:\t\tselect CRYPTO_LIB_UTILS\n  12:\t\tselect NET_CRC32C\n  13:\t\tselect NET_UDP_TUNNEL\n  14:\t\thelp\n  15:\t\t  Stream Control Transmission Protocol\n  16:\t\n  17:\t\t  From RFC 2960 \u003chttp://www.ietf.org/rfc/rfc2960.txt\u003e.\n  18:\t\n  19:\t\t  \"SCTP is a reliable transport protocol operating on top of a\n  20:\t\t  connectionless packet network such as IP.  It offers the following\n"
}

gemini-3.1-pro-preview

null

null

							input: 4473
							output: 114
							thoughts: 188
						

**Fuzzing Focus: SCTP T3-Rtx Handling with Zero Window Peers**

Okay, so I'm looking at this patch and my initial thought is: since `IP_SCTP` relies on `INET`, just enabling `IP_SCTP` should give me everything I need for this fuzzing effort. No need to overcomplicate the config. The patch itself is touching `sctp_sf_do_6_3_3_rtx` in `net/sctp/sm_statefuns.c`. This is *gold* – it's right in the heart of SCTP's T3-rtx timeout handling, specifically dealing with retransmissions. That's a critical area, especially when a peer signals a zero window.

My intuition says this is a definite candidate for fuzzing. This patch is fundamentally changing how the SCTP state machine behaves when it's dealing with retransmissions and a zero window, which means there's a good chance of introducing regressions or some kind of unanticipated behavior. So `sctp_sf_do_6_3_3_rtx` is clearly the key symbol here; it's where the action is. I'm going to set that as my focus for the fuzzing analysis. The configuration to enable is simple: `IP_SCTP`, which should provide enough coverage for fuzzing this specific state function.

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_sf_do_6_3_3_rtx"
  ],
  "Reasoning": "The patch modifies the condition for handling T3-rtx timer expirations in SCTP when the peer has announced a zero window. This is a functional change in the core SCTP state machine logic and should be fuzzed to ensure it doesn't introduce regressions or unexpected behavior.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_sf_do_6_3_3_rtx"
  ],
  "Reasoning": "The patch modifies the condition for handling T3-rtx timer expirations in SCTP when the peer has announced a zero window. This is a functional change in the core SCTP state machine logic and should be fuzzed to ensure it doesn't introduce regressions or unexpected behavior.",
  "WorthFuzzing": true
}