AI Trajectory

null

{
  "EnableConfigs": [
    "TIPC"
  ],
  "FocusSymbols": [
    "__tipc_shutdown",
    "tipc_sk_conn_proto_rcv",
    "tipc_sk_proto_rcv",
    "tipc_sk_filter_connect"
  ],
  "Reasoning": "The patch modifies the behavior of tipc_sk_push_backlog to defer transmission to the caller by adding to xmitq instead of calling tipc_node_xmit directly. This is a functional change in TIPC socket code.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit 4ae35503dbe175109137792d8773cc5c119d5bf9\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Wed Jul 22 20:24:18 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/net/tipc/socket.c b/net/tipc/socket.c\nindex e564341e0216d3..4b3d8193d8a824 100644\n--- a/net/tipc/socket.c\n+++ b/net/tipc/socket.c\n@@ -156,7 +156,8 @@ static int tipc_sk_insert(struct tipc_sock *tsk);\n static void tipc_sk_remove(struct tipc_sock *tsk);\n static int __tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dsz);\n static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dsz);\n-static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack);\n+static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack,\n+\t\t\t\t struct sk_buff_head *xmitq);\n static int tipc_wait_for_connect(struct socket *sock, long *timeo_p);\n \n static const struct proto_ops packet_ops;\n@@ -560,7 +561,7 @@ static void __tipc_shutdown(struct socket *sock, int error)\n \t\t\t\t\t    !tsk_conn_cong(tsk)));\n \n \t/* Push out delayed messages if in Nagle mode */\n-\ttipc_sk_push_backlog(tsk, false);\n+\ttipc_sk_push_backlog(tsk, false, NULL);\n \t/* Remove pending SYN */\n \t__skb_queue_purge(\u0026sk-\u003esk_write_queue);\n \n@@ -1268,7 +1269,8 @@ void tipc_sk_mcast_rcv(struct net *net, struct sk_buff_head *arrvq,\n /* tipc_sk_push_backlog(): send accumulated buffers in socket write queue\n  *                         when socket is in Nagle mode\n  */\n-static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack)\n+static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack,\n+\t\t\t\t struct sk_buff_head *xmitq)\n {\n \tstruct sk_buff_head *txq = \u0026tsk-\u003esk.sk_write_queue;\n \tstruct sk_buff *skb = skb_peek_tail(txq);\n@@ -1310,6 +1312,12 @@ static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack)\n \t\ttsk-\u003epkt_cnt += skb_queue_len(txq);\n \ttsk-\u003esnt_unacked += tsk-\u003esnd_backlog;\n \ttsk-\u003esnd_backlog = 0;\n+\n+\tif (xmitq) {\n+\t\tskb_queue_splice_tail_init(txq, xmitq);\n+\t\treturn;\n+\t}\n+\n \trc = tipc_node_xmit(net, txq, dnode, tsk-\u003eportid);\n \tif (rc == -ELINKCONG)\n \t\ttsk-\u003econg_link_cnt = 1;\n@@ -1367,7 +1375,7 @@ static void tipc_sk_conn_proto_rcv(struct tipc_sock *tsk, struct sk_buff *skb,\n \t\t\tgoto exit;\n \n \t\twas_cong = tsk_conn_cong(tsk);\n-\t\ttipc_sk_push_backlog(tsk, msg_nagle_ack(hdr));\n+\t\ttipc_sk_push_backlog(tsk, msg_nagle_ack(hdr), xmitq);\n \t\ttsk-\u003esnt_unacked -= msg_conn_ack(hdr);\n \t\tif (tsk-\u003epeer_caps \u0026 TIPC_BLOCK_FLOWCTL)\n \t\t\ttsk-\u003esnd_win = msg_adv_win(hdr);\n@@ -2165,7 +2173,7 @@ static void tipc_sk_proto_rcv(struct sock *sk,\n \t\tsmp_wmb();\n \t\ttsk-\u003econg_link_cnt--;\n \t\twakeup = true;\n-\t\ttipc_sk_push_backlog(tsk, false);\n+\t\ttipc_sk_push_backlog(tsk, false, xmitq);\n \t\tbreak;\n \tcase GROUP_PROTOCOL:\n \t\ttipc_group_proto_rcv(grp, \u0026wakeup, hdr, inputq, xmitq);\n@@ -2256,7 +2264,7 @@ static bool tipc_sk_filter_connect(struct tipc_sock *tsk, struct sk_buff *skb,\n \t\treturn false;\n \tcase TIPC_ESTABLISHED:\n \t\tif (!skb_queue_empty(\u0026sk-\u003esk_write_queue))\n-\t\t\ttipc_sk_push_backlog(tsk, false);\n+\t\t\ttipc_sk_push_backlog(tsk, false, xmitq);\n \t\t/* Accept only connection-based messages sent by peer */\n \t\tif (likely(con_msg \u0026\u0026 !err \u0026\u0026 pport == oport \u0026\u0026\n \t\t\t   pnode == onode)) {\n"
}

best-expensive

null

{
  "EnableConfigs": [
    "TIPC"
  ],
  "FocusSymbols": [
    "__tipc_shutdown",
    "tipc_sk_conn_proto_rcv",
    "tipc_sk_proto_rcv",
    "tipc_sk_filter_connect"
  ],
  "Reasoning": "The patch modifies the behavior of tipc_sk_push_backlog to defer transmission to the caller by adding to xmitq instead of calling tipc_node_xmit directly. This is a functional change in TIPC socket code.",
  "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 4ae35503dbe175109137792d8773cc5c119d5bf9
Author: syz-cluster <triage@syzkaller.com>
Date:   Wed Jul 22 20:24:18 2026 +0000

    syz-cluster: applied patch under review

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index e564341e0216d3..4b3d8193d8a824 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -156,7 +156,8 @@ static int tipc_sk_insert(struct tipc_sock *tsk);
 static void tipc_sk_remove(struct tipc_sock *tsk);
 static int __tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dsz);
 static int __tipc_sendmsg(struct socket *sock, struct msghdr *m, size_t dsz);
-static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack);
+static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack,
+				 struct sk_buff_head *xmitq);
 static int tipc_wait_for_connect(struct socket *sock, long *timeo_p);
 
 static const struct proto_ops packet_ops;
@@ -560,7 +561,7 @@ static void __tipc_shutdown(struct socket *sock, int error)
 					    !tsk_conn_cong(tsk)));
 
 	/* Push out delayed messages if in Nagle mode */
-	tipc_sk_push_backlog(tsk, false);
+	tipc_sk_push_backlog(tsk, false, NULL);
 	/* Remove pending SYN */
 	__skb_queue_purge(&sk->sk_write_queue);
 
@@ -1268,7 +1269,8 @@ void tipc_sk_mcast_rcv(struct net *net, struct sk_buff_head *arrvq,
 /* tipc_sk_push_backlog(): send accumulated buffers in socket write queue
  *                         when socket is in Nagle mode
  */
-static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack)
+static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack,
+				 struct sk_buff_head *xmitq)
 {
 	struct sk_buff_head *txq = &tsk->sk.sk_write_queue;
 	struct sk_buff *skb = skb_peek_tail(txq);
@@ -1310,6 +1312,12 @@ static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack)
 		tsk->pkt_cnt += skb_queue_len(txq);
 	tsk->snt_unacked += tsk->snd_backlog;
 	tsk->snd_backlog = 0;
+
+	if (xmitq) {
+		skb_queue_splice_tail_init(txq, xmitq);
+		return;
+	}
+
 	rc = tipc_node_xmit(net, txq, dnode, tsk->portid);
 	if (rc == -ELINKCONG)
 		tsk->cong_link_cnt = 1;
@@ -1367,7 +1375,7 @@ static void tipc_sk_conn_proto_rcv(struct tipc_sock *tsk, struct sk_buff *skb,
 			goto exit;
 
 		was_cong = tsk_conn_cong(tsk);
-		tipc_sk_push_backlog(tsk, msg_nagle_ack(hdr));
+		tipc_sk_push_backlog(tsk, msg_nagle_ack(hdr), xmitq);
 		tsk->snt_unacked -= msg_conn_ack(hdr);
 		if (tsk->peer_caps & TIPC_BLOCK_FLOWCTL)
 			tsk->snd_win = msg_adv_win(hdr);
@@ -2165,7 +2173,7 @@ static void tipc_sk_proto_rcv(struct sock *sk,
 		smp_wmb();
 		tsk->cong_link_cnt--;
 		wakeup = true;
-		tipc_sk_push_backlog(tsk, false);
+		tipc_sk_push_backlog(tsk, false, xmitq);
 		break;
 	case GROUP_PROTOCOL:
 		tipc_group_proto_rcv(grp, &wakeup, hdr, inputq, xmitq);
@@ -2256,7 +2264,7 @@ static bool tipc_sk_filter_connect(struct tipc_sock *tsk, struct sk_buff *skb,
 		return false;
 	case TIPC_ESTABLISHED:
 		if (!skb_queue_empty(&sk->sk_write_queue))
-			tipc_sk_push_backlog(tsk, false);
+			tipc_sk_push_backlog(tsk, false, xmitq);
 		/* Accept only connection-based messages sent by peer */
 		if (likely(con_msg && !err && pport == oport &&
 			   pnode == onode)) {

gemini-3.1-pro-preview

null

null

							input: 2977
							output: 28
							thoughts: 358
						

**Analyzing the TIPC Socket Patch**

Okay, so I'm looking at this patch for `net/tipc/socket.c`. It's a signature change for `tipc_sk_push_backlog`, adding a `struct sk_buff_head *xmitq` argument. Alright, seems like a pretty targeted modification.

Let's see, the function now conditionally splices `txq` to `xmitq` if `xmitq` isn't NULL and then returns, bypassing the usual `tipc_node_xmit` call. Essentially, it's deferring transmission to the caller, placing the packets on `xmitq` to be handled later. So, functionally, yeah, this is a distinct change in the socket behavior specifically when `xmitq` is supplied.

Now, let's nail down where this comes into play. I need to remember the TIPC config. Ah, right, `CONFIG_TIPC` will get me there.

Now, let's zoom in on the relevant symbols. The function in question, `tipc_sk_push_backlog`, is static. A quick look at the callers reveals some interesting details. I see that `__tipc_shutdown` calls it, but with `xmitq` set to NULL. Then there are other callers: `tipc_sk_conn_proto_rcv`, `tipc_sk_proto_rcv`, and `tipc_sk_filter_connect` that seem to be passing in an `xmitq` (likely their own transmit queues). So that's the key difference. These three functions will now behave differently after this patch! Let's make sure I'm not missing anything. I should probably double check the relevant configs before going any further.

{
  "Expression": "config TIPC",
  "PathPrefix": "net/tipc/"
}

{
  "Output": "net/tipc/Kconfig-5-\nnet/tipc/Kconfig:6:menuconfig TIPC\nnet/tipc/Kconfig-7-\ttristate \"The TIPC Protocol\"\n--\nnet/tipc/Kconfig-23-\nnet/tipc/Kconfig:24:config TIPC_MEDIA_IB\nnet/tipc/Kconfig-25-\tbool \"InfiniBand media type support\"\n--\nnet/tipc/Kconfig-29-\t  IP-over-InfiniBand devices.\nnet/tipc/Kconfig:30:config TIPC_MEDIA_UDP\nnet/tipc/Kconfig-31-\tbool \"IP/UDP media type support\"\n--\nnet/tipc/Kconfig-37-\nnet/tipc/Kconfig:38:config TIPC_CRYPTO\nnet/tipc/Kconfig-39-\tbool \"TIPC encryption support\"\n--\nnet/tipc/Kconfig-52-\nnet/tipc/Kconfig:53:config TIPC_DIAG\nnet/tipc/Kconfig-54-\ttristate \"TIPC: socket monitoring interface\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 4035
							output: 39
							thoughts: 89
						

**Analyzing the TIPC Configuration**

Okay, so the configuration in question is `TIPC`. My initial thought is to zero in on these symbols: `tipc_sk_conn_proto_rcv`, `tipc_sk_proto_rcv`, and `tipc_sk_filter_connect`. My next step is to quickly determine if any *other* configurations are required alongside `TIPC`. That should be straightforward. Based on my experience, I'm fairly certain `TIPC` alone is sufficient, but I'll confirm that quickly. Then, I need to check the nature of `tipc_sk_conn_proto_rcv`. Specifically, is it a statically linked function? That's the key question.

{
  "Expression": "tipc_sk_conn_proto_rcv",
  "PathPrefix": "net/tipc/socket.c"
}

{
  "Output": "net/tipc/socket.c=1272=static void tipc_sk_push_backlog(struct tipc_sock *tsk, bool nagle_ack,\n--\nnet/tipc/socket.c-1326-/**\nnet/tipc/socket.c:1327: * tipc_sk_conn_proto_rcv - receive a connection mng protocol message\nnet/tipc/socket.c-1328- * @tsk: receiving socket\n--\nnet/tipc/socket.c-1332- */\nnet/tipc/socket.c:1333:static void tipc_sk_conn_proto_rcv(struct tipc_sock *tsk, struct sk_buff *skb,\nnet/tipc/socket.c-1334-\t\t\t\t   struct sk_buff_head *inputq,\n--\nnet/tipc/socket.c=2156=static void tipc_sk_proto_rcv(struct sock *sk,\n--\nnet/tipc/socket.c-2167-\tcase CONN_MANAGER:\nnet/tipc/socket.c:2168:\t\ttipc_sk_conn_proto_rcv(tsk, skb, inputq, xmitq);\nnet/tipc/socket.c-2169-\t\treturn;\n"
}

gemini-3.1-pro-preview

null

null

							input: 4651
							output: 36
							thoughts: 62
						

**Analyzing TIPC Socket Connection Handling**

Okay, so I'm looking at some TIPC socket-related functions here. I see that `tipc_sk_conn_proto_rcv`, `tipc_sk_proto_rcv`, and `tipc_sk_filter_connect` are all defined as static. Hmm, that's interesting. It means their scope is limited within the current compilation unit, which is typical for helper functions or those not intended for direct external use.

Now, my focus shifts to `tipc_sk_filter_connect`. Given that it's static, I want to understand how it's being used internally. Let's dig into the callers of `tipc_sk_filter_connect`. Understanding who calls it will shed light on its role within the TIPC connection process and how it's employed in filtering or managing socket connections. Time to trace those call paths.

{
  "Expression": "tipc_sk_filter_connect",
  "PathPrefix": "net/tipc/socket.c"
}

{
  "Output": "net/tipc/socket.c=2156=static void tipc_sk_proto_rcv(struct sock *sk,\n--\nnet/tipc/socket.c-2195-/**\nnet/tipc/socket.c:2196: * tipc_sk_filter_connect - check incoming message for a connection-based socket\nnet/tipc/socket.c-2197- * @tsk: TIPC socket\n--\nnet/tipc/socket.c-2201- */\nnet/tipc/socket.c:2202:static bool tipc_sk_filter_connect(struct tipc_sock *tsk, struct sk_buff *skb,\nnet/tipc/socket.c-2203-\t\t\t\t   struct sk_buff_head *xmitq)\n--\nnet/tipc/socket.c=2346=static void tipc_sk_filter_rcv(struct sock *sk, struct sk_buff *skb,\n--\nnet/tipc/socket.c-2375-\t\tlimit = rcvbuf_limit(sk, skb);\nnet/tipc/socket.c:2376:\t\tif ((sk_conn \u0026\u0026 !tipc_sk_filter_connect(tsk, skb, xmitq)) ||\nnet/tipc/socket.c-2377-\t\t    (!sk_conn \u0026\u0026 msg_connected(hdr)) ||\n"
}

gemini-3.1-pro-preview

null

null

							input: 5294
							output: 37
							thoughts: 22
						

Here's a summary of my understanding, framed in the first person:

**My Internal Processing of `tipc_sk_filter_rcv`**

Okay, so I'm looking at `tipc_sk_filter_rcv`...and what immediately jumps out at me is that it calls `tipc_sk_filter_connect`. That's the key connection. This tells me that the receive path for a filtered socket also needs to interact with the connection filtering logic. This suggests that the filtering isn't just a simple packet inspection at receive, but might also consider the state of the connection or, potentially, the connect attempts themselves. It’s got me thinking: is the filtering dynamic? Does it change depending on the connection state, or is it a more static rule applied at connect time that then informs receive? And is the filtering *only* done at connect, or is it also actively present during a live connection? I need to dig deeper into the specifics of `tipc_sk_filter_connect` to really grasp the filtering workflow.

{
  "Expression": "tipc_sk_filter_rcv",
  "PathPrefix": "net/tipc/socket.c"
}

{
  "Output": "net/tipc/socket.c=2318=static unsigned int rcvbuf_limit(struct sock *sk, struct sk_buff *skb)\n--\nnet/tipc/socket.c-2335-/**\nnet/tipc/socket.c:2336: * tipc_sk_filter_rcv - validate incoming message\nnet/tipc/socket.c-2337- * @sk: socket\n--\nnet/tipc/socket.c-2345- */\nnet/tipc/socket.c:2346:static void tipc_sk_filter_rcv(struct sock *sk, struct sk_buff *skb,\nnet/tipc/socket.c-2347-\t\t\t       struct sk_buff_head *xmitq)\n--\nnet/tipc/socket.c-2357-\nnet/tipc/socket.c:2358:\ttrace_tipc_sk_filter_rcv(sk, skb, TIPC_DUMP_ALL, \" \");\nnet/tipc/socket.c-2359-\tTIPC_SKB_CB(skb)-\u003ebytes_read = 0;\n--\nnet/tipc/socket.c=2411=static int tipc_sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)\n--\nnet/tipc/socket.c-2418-\nnet/tipc/socket.c:2419:\ttipc_sk_filter_rcv(sk, skb, \u0026xmitq);\nnet/tipc/socket.c-2420-\tadded = sk_rmem_alloc_get(sk) - before;\n--\nnet/tipc/socket.c=2438=static void tipc_sk_enqueue(struct sk_buff_head *inputq, struct sock *sk,\n--\nnet/tipc/socket.c-2456-\t\tif (!sock_owned_by_user(sk)) {\nnet/tipc/socket.c:2457:\t\t\ttipc_sk_filter_rcv(sk, skb, xmitq);\nnet/tipc/socket.c-2458-\t\t\tcontinue;\n"
}

gemini-3.1-pro-preview

null

null

							input: 6125
							output: 129
							thoughts: 275
						

**Analyzing the TIPC Socket Receive Path**

Okay, so I'm looking at how incoming packets are handled in TIPC sockets. My initial thought was to examine the connections between `tipc_sk_backlog_rcv`, the backlog receive function, and `tipc_sk_enqueue`, the function called when packets are actually received. I quickly realized that both of those functions call `tipc_sk_filter_rcv`, making that an important element as well.

Given that, I initially identified a set of functions that seemed central: `tipc_sk_conn_proto_rcv`, `tipc_sk_proto_rcv`, `tipc_sk_filter_connect`, `tipc_sk_filter_rcv`, `tipc_sk_backlog_rcv`, and `tipc_sk_enqueue`. However, I've decided to narrow my focus for now.

Wait, I think I have it. I should shift the focus to `tipc_sk_push_backlog`. It appears to be the function that has been modified, and importantly, it's static. That means the best way to understand its role is by looking at its callers. So, I will focus on the four functions that call `tipc_sk_push_backlog`, which are `__tipc_shutdown`, `tipc_sk_conn_proto_rcv`, `tipc_sk_proto_rcv`, and `tipc_sk_filter_connect`. These will give me a good handle on its usage.

{
  "EnableConfigs": [
    "TIPC"
  ],
  "FocusSymbols": [
    "__tipc_shutdown",
    "tipc_sk_conn_proto_rcv",
    "tipc_sk_proto_rcv",
    "tipc_sk_filter_connect"
  ],
  "Reasoning": "The patch modifies the behavior of tipc_sk_push_backlog to defer transmission to the caller by adding to xmitq instead of calling tipc_node_xmit directly. This is a functional change in TIPC socket code.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "TIPC"
  ],
  "FocusSymbols": [
    "__tipc_shutdown",
    "tipc_sk_conn_proto_rcv",
    "tipc_sk_proto_rcv",
    "tipc_sk_filter_connect"
  ],
  "Reasoning": "The patch modifies the behavior of tipc_sk_push_backlog to defer transmission to the caller by adding to xmitq instead of calling tipc_node_xmit directly. This is a functional change in TIPC socket code.",
  "WorthFuzzing": true
}