[PATCH] tipc: defer local Nagle backlog xmit from receive path

[PATCH] tipc: defer local Nagle backlog xmit from receive path

[syzbot]

From: Bartosz Chronowski <immersa.bartosz.chronowski@gmail.com>

A local TIPC stream socket workload can trap a CPU in an endless receive
loop. The resulting soft lockup can make the system unavailable.

tipc_sk_push_backlog() can transmit delayed stream data while tipc_sk_rcv()
holds a destination socket's sk_lock.slock. Own-node transmission enters
tipc_sk_rcv() synchronously. A reply that reaches the ancestor socket
cannot acquire the still-held lock, and tipc_sk_rcv() retries without
consuming its input queue.

Pass the receive output queue to tipc_sk_push_backlog() from receive-side
callers. Queue own-node output there so the enclosing receive path sends it
after releasing the socket lock. Keep shutdown and remote-node transmission
on the existing direct path, preserving remote link congestion handling.

Fixes: c0bceb97db9e ("tipc: add smart nagle feature")
Assisted-by: Gemini:gemini-3.5-flash Gemini:gemini-3.1-pro-preview syzbot
Reported-by: syzbot+10a41dc44eef71aa9450@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=10a41dc44eef71aa9450
Link: https://syzkaller.appspot.com/ai_job?id=aa2dc129-33d3-42e7-bd0b-bf2198c9c9c2
Signed-off-by: Bartosz Chronowski <immersa.bartosz.chronowski@gmail.com>

---
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index e564341e0..33d744dc5 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);
 
@@ -1267,8 +1268,10 @@ 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
+ * @xmitq: receive output queue, or NULL outside receive context
  */
-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 +1313,12 @@ 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 && in_own_node(net, dnode)) {
+		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 +1376,7 @@ 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 +2174,7 @@ 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 +2265,7 @@ 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)) {


base-commit: 1590cf0329716306e948a8fc29f1d3ee87d3989f
-- 
See https://goo.gle/syzbot-ai-patches for information about AI-generated patches.
The person who has signed off on the patch is responsible for
addressing comments.
syzbot engineers can be reached at syzkaller@googlegroups.com.

RE: [PATCH] tipc: defer local Nagle backlog xmit from receive path

[Tung Quang Nguyen]

>Subject: [PATCH] tipc: defer local Nagle backlog xmit from receive path
>
>From: Bartosz Chronowski <immersa.bartosz.chronowski@gmail.com>
>
>A local TIPC stream socket workload can trap a CPU in an endless receive loop.
>The resulting soft lockup can make the system unavailable.
>
>tipc_sk_push_backlog() can transmit delayed stream data while tipc_sk_rcv()
>holds a destination socket's sk_lock.slock. Own-node transmission enters
>tipc_sk_rcv() synchronously. A reply that reaches the ancestor socket cannot
>acquire the still-held lock, and tipc_sk_rcv() retries without consuming its input
>queue.
>
>Pass the receive output queue to tipc_sk_push_backlog() from receive-side
>callers. Queue own-node output there so the enclosing receive path sends it
>after releasing the socket lock. Keep shutdown and remote-node transmission
>on the existing direct path, preserving remote link congestion handling.
>
>Fixes: c0bceb97db9e ("tipc: add smart nagle feature")
>Assisted-by: Gemini:gemini-3.5-flash Gemini:gemini-3.1-pro-preview syzbot
>Reported-by: syzbot+10a41dc44eef71aa9450@syzkaller.appspotmail.com
>Closes: https://syzkaller.appspot.com/bug?extid=10a41dc44eef71aa9450
>Link: https://syzkaller.appspot.com/ai_job?id=aa2dc129-33d3-42e7-bd0b-
>bf2198c9c9c2
>Signed-off-by: Bartosz Chronowski <immersa.bartosz.chronowski@gmail.com>
>
>---
>diff --git a/net/tipc/socket.c b/net/tipc/socket.c index e564341e0..33d744dc5
>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);

This is wrong because it breaks user applications (send()/close()) as well as current implementation.
All pending messages in the socket queue need to be delivered before closing that socket.

> 	/* Remove pending SYN */
> 	__skb_queue_purge(&sk->sk_write_queue);
>
>@@ -1267,8 +1268,10 @@ 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
>+ * @xmitq: receive output queue, or NULL outside receive context
>  */
>-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 +1313,12 @@
>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 && in_own_node(net, dnode)) {
>+		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 +1376,7 @@ 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);

Passing a stack-based queue (local variable) to tipc_sk_push_backlog() is a wrong approach.
This will break user applications because it will create out-of-order messages at receiver.

' tsk->sk.sk_write_queue' must always be sent under lock protection. After you copy its skbs to the local ' xmitq', 
there could be 2 threads sending ' tsk->sk.sk_write_queue' and 'xmitq'. This causes disordered messages.

> 		tsk->snt_unacked -= msg_conn_ack(hdr);
> 		if (tsk->peer_caps & TIPC_BLOCK_FLOWCTL)
> 			tsk->snd_win = msg_adv_win(hdr);
>@@ -2165,7 +2174,7 @@ 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 +2265,7 @@ 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)) {
>
>
>base-commit: 1590cf0329716306e948a8fc29f1d3ee87d3989f
>--
>See https://goo.gle/syzbot-ai-patches for information about AI-generated
>patches.
>The person who has signed off on the patch is responsible for addressing
>comments.
>syzbot engineers can be reached at syzkaller@googlegroups.com.

Re: [PATCH] tipc: defer local Nagle backlog xmit from receive path

[Bartosz Chronowski]

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 1590cf0329716306e948a8fc29f1d3ee87d3989f

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index e564341e0216d35ae4fe539576b6e0be89b84ddb..0bf259672827db095046cda5646df047002dd663 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -94,6 +94,7 @@ struct sockaddr_pair {
  * @peer: 'connected' peer for dgram/rdm
  * @node: hash table node
  * @mc_method: cookie for use between socket and broadcast layer
+ * @backlog_work: processes receive backlog under socket ownership
  * @rcu: rcu struct for tipc_sock
  * @group: TIPC communications group
  * @oneway: message count in one direction (FIXME)
@@ -128,6 +129,7 @@ struct tipc_sock {
 	struct sockaddr_tipc peer;
 	struct rhash_head node;
 	struct tipc_mc_method mc_method;
+	struct work_struct backlog_work;
 	struct rcu_head rcu;
 	struct tipc_group *group;
 	u32 oneway;
@@ -143,6 +145,7 @@ struct tipc_sock {
 };
 
 static int tipc_sk_backlog_rcv(struct sock *sk, struct sk_buff *skb);
+static void tipc_sk_backlog_work(struct work_struct *work);
 static void tipc_data_ready(struct sock *sk);
 static void tipc_write_space(struct sock *sk);
 static void tipc_sock_destruct(struct sock *sk);
@@ -520,6 +523,7 @@ static int tipc_sk_create(struct net *net, struct socket *sock,
 	sk->sk_data_ready = tipc_data_ready;
 	sk->sk_write_space = tipc_write_space;
 	sk->sk_destruct = tipc_sock_destruct;
+	INIT_WORK(&tsk->backlog_work, tipc_sk_backlog_work);
 	tsk->conn_timeout = CONN_TIMEOUT_DEFAULT;
 	tsk->group_is_open = true;
 	atomic_set(&tsk->dupl_rcvcnt, 0);
@@ -2417,6 +2421,17 @@ static int tipc_sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 	return 0;
 }
 
+static void tipc_sk_backlog_work(struct work_struct *work)
+{
+	struct tipc_sock *tsk = container_of(work, struct tipc_sock,
+					     backlog_work);
+	struct sock *sk = &tsk->sk;
+
+	lock_sock(sk);
+	release_sock(sk);
+	sock_put(sk);
+}
+
 /**
  * tipc_sk_enqueue - extract all buffers with destination 'dport' from
  *                   inputq and try adding them to socket or backlog queue
@@ -2434,18 +2449,30 @@ static void tipc_sk_enqueue(struct sk_buff_head *inputq, struct sock *sk,
 	struct sk_buff *skb;
 	unsigned int lim;
 	atomic_t *dcnt;
+	bool deferred = false;
+	bool owned;
+	bool local_backlog;
 	u32 onode;
 
 	while (skb_queue_len(inputq)) {
 		if (unlikely(time_after_eq(jiffies, time_limit)))
-			return;
+			break;
 
 		skb = tipc_skb_dequeue(inputq, dport);
 		if (unlikely(!skb))
-			return;
+			break;
 
-		/* Add message directly to receive queue if possible */
-		if (!sock_owned_by_user(sk)) {
+		/*
+		 * A local Nagle backlog may loop back into this socket while its
+		 * spinlock is held.  Queue the triggering input for processing under
+		 * socket ownership, which keeps a concurrent sender from overtaking
+		 * the already queued output.
+		 */
+		owned = sock_owned_by_user(sk);
+		local_backlog = !skb_queue_empty(&sk->sk_write_queue) &&
+				in_own_node(sock_net(sk),
+					    tsk_peer_node(tipc_sk(sk)));
+		if (!owned && !local_backlog) {
 			tipc_sk_filter_rcv(sk, skb, xmitq);
 			continue;
 		}
@@ -2456,6 +2483,7 @@ static void tipc_sk_enqueue(struct sk_buff_head *inputq, struct sock *sk,
 			atomic_set(dcnt, 0);
 		lim = rcvbuf_limit(sk, skb) + atomic_read(dcnt);
 		if (likely(!sk_add_backlog(sk, skb, lim))) {
+			deferred |= !owned;
 			trace_tipc_sk_overlimit1(sk, skb, TIPC_DUMP_SK_BKLGQ,
 						 "bklg & rcvq >90% allocated!");
 			continue;
@@ -2472,6 +2500,12 @@ static void tipc_sk_enqueue(struct sk_buff_head *inputq, struct sock *sk,
 		}
 		break;
 	}
+
+	if (deferred) {
+		sock_hold(sk);
+		if (!schedule_work(&tipc_sk(sk)->backlog_work))
+			sock_put(sk);
+	}
 }
 
 /**

Re: [syzbot] [tipc?] BUG: soft lockup in do_sock_setsockopt

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+10a41dc44eef71aa9450@syzkaller.appspotmail.com
Tested-by: syzbot+10a41dc44eef71aa9450@syzkaller.appspotmail.com

Tested on:

commit:         1590cf03 Linux 7.2-rc4
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=17a00949580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8e9390a601b4f3bd
dashboard link: https://syzkaller.appspot.com/bug?extid=10a41dc44eef71aa9450
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch:          https://syzkaller.appspot.com/x/patch.diff?x=10baba9e580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [tipc?] BUG: soft lockup in do_sock_setsockopt

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+10a41dc44eef71aa9450@syzkaller.appspotmail.com
Tested-by: syzbot+10a41dc44eef71aa9450@syzkaller.appspotmail.com

Tested on:

commit:         a13307e9 Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=161d3132580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7ea511081a30ab4a
dashboard link: https://syzkaller.appspot.com/bug?extid=10a41dc44eef71aa9450
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch:          https://syzkaller.appspot.com/x/patch.diff?x=118e3132580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [tipc?] BUG: soft lockup in do_sock_setsockopt

[Bartosz Chronowski]

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git a13307e97d5c54b65720bb71fa379960ded1e51a

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index d5d70eb230b5..f3c4bccaadc8 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;
@@ -561,7 +562,7 @@ 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);

@@ -1268,8 +1269,10 @@ 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
+ * @xmitq: receive output queue, or NULL outside receive context
  */
-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);
@@ -1311,6 +1314,10 @@ 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 && in_own_node(net, dnode)) {
+               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;
@@ -1368,7 +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);
@@ -2166,7 +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);
@@ -2257,7 +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)) {


On Mon, Aug 10, 2026 at 07:00:05AM -0700, syzbot wrote:
> Hello,
> 
> syzbot tried to test the proposed patch but the build/boot failed:
> 
> failed to checkout kernel repo git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git on commit a13307e97d5c54b65720bb71fa379960ded1e51a: failed to run ["git" "-c" "core.hooksPath=/dev/null" "fetch" "--force" "--tags" "f569e972c8e9057ee9c286220c83a480ebf30cc5" "a13307e97d5c54b65720bb71fa379960ded1e51a"]: exit status 128
> 
> 
> Tested on:
> 
> commit:         [unknown 
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git a13307e97d5c54b65720bb71fa379960ded1e51a
> kernel config:  https://syzkaller.appspot.com/x/.config?x=555131780f7c7272
> dashboard link: https://syzkaller.appspot.com/bug?extid=10a41dc44eef71aa9450
> compiler:       
> patch:          https://syzkaller.appspot.com/x/patch.diff?x=13c8a079580000
> 

Re: [syzbot] [tipc?] BUG: soft lockup in do_sock_setsockopt

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to checkout kernel repo git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git on commit a13307e97d5c54b65720bb71fa379960ded1e51a: failed to run ["git" "-c" "core.hooksPath=/dev/null" "fetch" "--force" "--tags" "f569e972c8e9057ee9c286220c83a480ebf30cc5" "a13307e97d5c54b65720bb71fa379960ded1e51a"]: exit status 128


Tested on:

commit:         [unknown 
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git a13307e97d5c54b65720bb71fa379960ded1e51a
kernel config:  https://syzkaller.appspot.com/x/.config?x=555131780f7c7272
dashboard link: https://syzkaller.appspot.com/bug?extid=10a41dc44eef71aa9450
compiler:       
patch:          https://syzkaller.appspot.com/x/patch.diff?x=13c8a079580000

Re: [syzbot] [tipc?] BUG: soft lockup in do_sock_setsockopt

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: soft lockup in do_sock_setsockopt

watchdog: BUG: soft lockup - CPU#0 stuck for 246s! [syz.0.68:6590]
Modules linked in:
irq event stamp: 407959825
hardirqs last  enabled at (407959824): [<ffffffff81c807ae>] __local_bh_enable_ip+0x9e/0x120 kernel/softirq.c:455
hardirqs last disabled at (407959825): [<ffffffff8b9d833e>] sysvec_apic_timer_interrupt+0xe/0xc0 arch/x86/kernel/apic/apic.c:1062
softirqs last  enabled at (58): [<ffffffff8b4025e1>] spin_unlock_bh include/linux/spinlock.h:396 [inline]
softirqs last  enabled at (58): [<ffffffff8b4025e1>] tipc_skb_peek_port net/tipc/msg.h:1235 [inline]
softirqs last  enabled at (58): [<ffffffff8b4025e1>] tipc_sk_rcv+0x2e1/0x1c80 net/tipc/socket.c:2496
softirqs last disabled at (60): [<ffffffff8b402618>] spin_trylock_bh include/linux/spinlock.h:414 [inline]
softirqs last disabled at (60): [<ffffffff8b402618>] tipc_sk_rcv+0x318/0x1c80 net/tipc/socket.c:2501
CPU: 0 UID: 0 PID: 6590 Comm: syz.0.68 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:121 [inline]
RIP: 0010:lock_release+0x5d/0x310 kernel/locking/lockdep.c:5881
Code: 87 07 02 00 00 48 0f a3 05 a0 51 36 0f 0f 82 02 02 00 00 44 8b 05 47 85 36 0f 45 85 c0 0f 84 48 01 00 00 65 8b 05 c3 6c 6f 12 <85> c0 0f 85 39 01 00 00 65 4c 8b 25 fb 25 6f 12 41 8b bc 24 9c 0b
RSP: 0018:ffffc90002e96b60 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffffffff8ebe6200 RCX: ffffffff8b3ea8cc
RDX: 0000000000000000 RSI: ffffffff8c3e9500 RDI: ffffffff8e420920
RBP: ffffffff8b3ea81a R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888030e0d800
R13: 0000000000000001 R14: 00000000240a719c R15: dffffc0000000000
FS:  00007f80f2b016c0(0000) GS:ffff888123edd000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f80f2b00ff8 CR3: 000000007840d000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 rcu_lock_release include/linux/rcupdate.h:310 [inline]
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 net_generic+0xef/0x2a0 include/net/netns/generic.h:48
 tipc_sk_lookup+0xa2/0xa00 net/tipc/socket.c:3001
 tipc_sk_rcv+0x2ee/0x1c80 net/tipc/socket.c:2497
 tipc_node_xmit+0x23e/0xfb0 net/tipc/node.c:1701
 tipc_node_xmit_skb net/tipc/node.c:1766 [inline]
 tipc_node_distr_xmit+0x177/0x3c0 net/tipc/node.c:1781
 tipc_sk_rcv+0xaab/0x1c80 net/tipc/socket.c:2506
 tipc_node_xmit+0x23e/0xfb0 net/tipc/node.c:1701
 tipc_sk_push_backlog+0x318/0xa00 net/tipc/socket.c:1314
 tipc_sk_conn_proto_rcv net/tipc/socket.c:1371 [inline]
 tipc_sk_proto_rcv net/tipc/socket.c:2161 [inline]
 tipc_sk_filter_rcv+0x248f/0x3250 net/tipc/socket.c:2357
 tipc_sk_enqueue net/tipc/socket.c:2450 [inline]
 tipc_sk_rcv+0xe90/0x1c80 net/tipc/socket.c:2502
 tipc_node_xmit+0x23e/0xfb0 net/tipc/node.c:1701
 tipc_node_xmit_skb net/tipc/node.c:1766 [inline]
 tipc_node_distr_xmit+0x177/0x3c0 net/tipc/node.c:1781
 tipc_sk_backlog_rcv+0x16f/0x1e0 net/tipc/socket.c:2417
 sk_backlog_rcv include/net/sock.h:1190 [inline]
 __release_sock+0x3a2/0x440 net/core/sock.c:3260
 release_sock+0x1e5/0x280 net/core/sock.c:3859
 sockopt_release_sock net/core/sock.c:1162 [inline]
 sk_setsockopt+0x46b/0x5d80 net/core/sock.c:1680
 do_sock_setsockopt+0x193/0x1d0 net/socket.c:2364
 __sys_setsockopt+0x195/0x220 net/socket.c:2393
 __do_sys_setsockopt net/socket.c:2399 [inline]
 __se_sys_setsockopt net/socket.c:2396 [inline]
 __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2396
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0x860 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f80f1b9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f80f2b01028 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f80f1e16090 RCX: 00007f80f1b9c819
RDX: 0000000000000021 RSI: 0000000000000001 RDI: 0000000000000003
RBP: 00007f80f1c32c91 R08: 0000000000000004 R09: 0000000000000000
R10: 0000200000000540 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f80f1e16128 R14: 00007f80f1e16090 R15: 00007ffff6021578
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6589 Comm: syz.0.68 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64
Code: 86 a4 02 e9 6e b8 72 f5 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 03 fa 2d 00 fb f4 <e9> 47 b8 72 f5 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffc90002e378d8 EFLAGS: 00000246
RAX: 000000000001931e RBX: 0000000000000003 RCX: 0000000000000004
RDX: 0000000000000000 RSI: ffffffff8e168355 RDI: ffffffff8c3e9580
RBP: ffff8880799cca50 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: 0000000000000003 R14: ffff8880b853c5c0 R15: 0000000000000000
FS:  00007f80f2b226c0(0000) GS:ffff888123fdd000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000000 CR3: 000000007840d000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline]
 kvm_wait arch/x86/kernel/kvm.c:1096 [inline]
 kvm_wait+0x124/0x160 arch/x86/kernel/kvm.c:1078
 pv_wait arch/x86/include/asm/paravirt-spinlock.h:83 [inline]
 pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:466 [inline]
 __pv_queued_spin_lock_slowpath+0x4b0/0xc00 kernel/locking/qspinlock.c:325
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt-spinlock.h:35 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/paravirt-spinlock.h:66 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x1e0/0x260 kernel/locking/spinlock_debug.c:116
 spin_lock_bh include/linux/spinlock.h:348 [inline]
 lock_sock_nested+0x5f/0xf0 net/core/sock.c:3846
 lock_sock include/net/sock.h:1713 [inline]
 tipc_sendstream+0x41/0x70 net/tipc/socket.c:1550
 sock_sendmsg_nosec net/socket.c:775 [inline]
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2684
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2738
 __sys_sendmsg+0x160/0x210 net/socket.c:2770
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0x860 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f80f1b9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f80f2b22028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f80f1e15fa0 RCX: 00007f80f1b9c819
RDX: 0000000000000000 RSI: 0000200000000780 RDI: 0000000000000004
RBP: 00007f80f1c32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f80f1e16038 R14: 00007f80f1e15fa0 R15: 00007ffff6021578
 </TASK>


Tested on:

commit:         a13307e9 Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=126c8fb9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7ea511081a30ab4a
dashboard link: https://syzkaller.appspot.com/bug?extid=10a41dc44eef71aa9450
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

Note: no patches were applied.

Re: [syzbot] [tipc?] BUG: soft lockup in do_sock_setsockopt

[syzbot]

syzbot has bisected this issue to:

commit 5f6bd380c7bdbe10f7b4e8ddcceed60ce0714c6d
Author: Peter Zijlstra <peterz@infradead.org>
Date:   Mon May 27 12:06:55 2024 +0000

    sched/rt: Remove default bandwidth control

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=104b93d0580000
start commit:   3efc57369a0c Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=124b93d0580000
console output: https://syzkaller.appspot.com/x/log.txt?x=144b93d0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a4fcb065287cdb84
dashboard link: https://syzkaller.appspot.com/bug?extid=10a41dc44eef71aa9450
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1636fe27980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=136b5e80580000

Reported-by: syzbot+10a41dc44eef71aa9450@syzkaller.appspotmail.com
Fixes: 5f6bd380c7bd ("sched/rt: Remove default bandwidth control")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: [syzbot] [tipc?] BUG: soft lockup in do_sock_setsockopt

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+10a41dc44eef71aa9450@syzkaller.appspotmail.com

Tested on:

commit:         707081b6 Merge branch 'for-next/core', remote-tracking..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=17e6b481180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=caeac3f3565b057a
dashboard link: https://syzkaller.appspot.com/bug?extid=10a41dc44eef71aa9450
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1222a94e180000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [tipc?] BUG: soft lockup in do_sock_setsockopt

[Hillf Danton]

On Fri, 22 Mar 2024 07:23:18 -0700
> syzbot found the following issue on:
> 
> HEAD commit:    707081b61156 Merge branch 'for-next/core', remote-tracking..
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=114e4c81180000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git  for-kernelci

--- x/net/tipc/socket.c
+++ y/net/tipc/socket.c
@@ -2488,6 +2488,11 @@ void tipc_sk_rcv(struct net *net, struct
 	struct tipc_sock *tsk;
 	struct sock *sk;
 	struct sk_buff *skb;
+	static int reent = 0;
+
+	if (reent)
+		return;
+	reent++;
 
 	__skb_queue_head_init(&xmitq);
 	while (skb_queue_len(inputq)) {
@@ -2524,6 +2529,7 @@ xmit:
 		dnode = msg_destnode(buf_msg(skb));
 		tipc_node_xmit_skb(net, skb, dnode, dport);
 	}
+	--reent;
 }
 
 static int tipc_wait_for_connect(struct socket *sock, long *timeo_p)
--

[syzbot] [tipc?] BUG: soft lockup in do_sock_setsockopt

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    707081b61156 Merge branch 'for-next/core', remote-tracking..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=16d23231180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=caeac3f3565b057a
dashboard link: https://syzkaller.appspot.com/bug?extid=10a41dc44eef71aa9450
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=126fea6e180000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=114e4c81180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6cad68bf7532/disk-707081b6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1a27e5400778/vmlinux-707081b6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/67dfc53755d0/Image-707081b6.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+10a41dc44eef71aa9450@syzkaller.appspotmail.com

watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [syz-executor178:13146]
Modules linked in:
irq event stamp: 29265101
hardirqs last  enabled at (29265100): [<ffff8000801dae10>] __local_bh_enable_ip+0x224/0x44c kernel/softirq.c:386
hardirqs last disabled at (29265101): [<ffff80008ad66a78>] __el1_irq arch/arm64/kernel/entry-common.c:533 [inline]
hardirqs last disabled at (29265101): [<ffff80008ad66a78>] el1_interrupt+0x24/0x68 arch/arm64/kernel/entry-common.c:551
softirqs last  enabled at (638): [<ffff80008a7fe730>] spin_unlock_bh include/linux/spinlock.h:396 [inline]
softirqs last  enabled at (638): [<ffff80008a7fe730>] tipc_skb_peek_port net/tipc/msg.h:1235 [inline]
softirqs last  enabled at (638): [<ffff80008a7fe730>] tipc_sk_rcv+0x34c/0x1888 net/tipc/socket.c:2494
softirqs last disabled at (640): [<ffff80008a7fe750>] spin_trylock_bh include/linux/spinlock.h:411 [inline]
softirqs last disabled at (640): [<ffff80008a7fe750>] tipc_sk_rcv+0x36c/0x1888 net/tipc/socket.c:2499
CPU: 0 PID: 13146 Comm: syz-executor178 Not tainted 6.8.0-rc7-syzkaller-g707081b61156 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : lock_acquire+0x278/0x71c
lr : lockdep_recursion_finish kernel/locking/lockdep.c:467 [inline]
lr : lock_acquire+0x248/0x71c kernel/locking/lockdep.c:5756
sp : ffff80009ab86080
x29: ffff80009ab86190 x28: dfff800000000000 x27: ffff700013570c1c
x26: ffff0001b3fffdc0 x25: ffff80008ee74ac0 x24: 0000000000000000
x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000000
x20: ffff80008ebebdc0 x19: ffff0001b3fffdc0 x18: ffff80009ab862e0
x17: 000000000000c55c x16: ffff80008ad6b1c0 x15: 0000000000000001
x14: ffff80008eca0458 x13: dfff800000000000 x12: 00000000af1c601b
x11: 00000000a4e03a31 x10: 0000000000000003 x9 : 0000000000000000
x8 : 00000000000000c0 x7 : ffff80008a80b3f8 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000002
x2 : 0000000000000008 x1 : ffff80008aedfba0 x0 : 0000000000000000
Call trace:
 __daif_local_irq_restore arch/arm64/include/asm/irqflags.h:176 [inline]
 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:196 [inline]
 lock_acquire+0x278/0x71c kernel/locking/lockdep.c:5757
 rcu_lock_acquire+0x40/0x4c include/linux/rcupdate.h:298
 rcu_read_lock include/linux/rcupdate.h:750 [inline]
 tipc_sk_lookup+0xc8/0x8b4 net/tipc/socket.c:3003
 tipc_sk_rcv+0x358/0x1888 net/tipc/socket.c:2495
 tipc_node_xmit+0x1b0/0xdb0 net/tipc/node.c:1703
 tipc_node_xmit_skb net/tipc/node.c:1768 [inline]
 tipc_node_distr_xmit+0x28c/0x3a4 net/tipc/node.c:1783
 tipc_sk_rcv+0x1280/0x1888 net/tipc/socket.c:2504
 tipc_node_xmit+0x1b0/0xdb0 net/tipc/node.c:1703
 tipc_sk_push_backlog net/tipc/socket.c:1317 [inline]
 tipc_sk_filter_connect net/tipc/socket.c:2258 [inline]
 tipc_sk_filter_rcv+0x13f8/0x2cac net/tipc/socket.c:2367
 tipc_sk_enqueue net/tipc/socket.c:2448 [inline]
 tipc_sk_rcv+0x6d0/0x1888 net/tipc/socket.c:2500
 tipc_node_xmit+0x1b0/0xdb0 net/tipc/node.c:1703
 tipc_node_xmit_skb net/tipc/node.c:1768 [inline]
 tipc_node_distr_xmit+0x28c/0x3a4 net/tipc/node.c:1783
 tipc_sk_backlog_rcv+0x164/0x214 net/tipc/socket.c:2415
 sk_backlog_rcv include/net/sock.h:1092 [inline]
 __release_sock+0x1a8/0x408 net/core/sock.c:2972
 release_sock+0x68/0x1b8 net/core/sock.c:3538
 sk_setsockopt+0xbdc/0x306c
 sock_setsockopt+0x68/0x80 net/core/sock.c:1548
 do_sock_setsockopt+0x238/0x4e0 net/socket.c:2307
 __sys_setsockopt+0x128/0x1a8 net/socket.c:2334
 __do_sys_setsockopt net/socket.c:2343 [inline]
 __se_sys_setsockopt net/socket.c:2340 [inline]
 __arm64_sys_setsockopt+0xb8/0xd4 net/socket.c:2340
 __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup