[syzbot ci] Re: vsock/virtio: fix memory leak in virtio_transport_recv_listen()

[syzbot ci]

syzbot ci has tested the following series

[v1] vsock/virtio: fix memory leak in virtio_transport_recv_listen()
https://lore.kernel.org/all/20260424150310.57...@gmail.com
* [PATCH] vsock/virtio: fix memory leak in virtio_transport_recv_listen()

and found the following issue:
possible deadlock in virtio_transport_recv_listen

Full report is available here:
https://ci.syzbot.org/series/e5f3f5f1-8e83-492f-833b-dc526b61d0ef

***

possible deadlock in virtio_transport_recv_listen

tree: net-next
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/netdev/net-next.git
base: e728258debd553c95d2e70f9cd97c9fde27c7130
arch: amd64
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config: https://ci.syzbot.org/builds/bcc67f3f-b441-4d11-8573-f26ca268da65/config
syz repro: https://ci.syzbot.org/findings/fce9fa9b-692a-420c-956f-12c7e6d75e2e/syz_repro

============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
kworker/1:5/6007 is trying to acquire lock:
ffff88817492e2a0 (sk_lock-AF_VSOCK){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
ffff88817492e2a0 (sk_lock-AF_VSOCK){+.+.}-{0:0}, at: virtio_transport_recv_listen+0x13a5/0x2230 net/vmw_vsock/virtio_transport_common.c:1593

but task is already holding lock:
ffff88817492e2a0 (sk_lock-AF_VSOCK){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
ffff88817492e2a0 (sk_lock-AF_VSOCK){+.+.}-{0:0}, at: virtio_transport_recv_pkt+0xfde/0x2bb0 net/vmw_vsock/virtio_transport_common.c:1671

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(sk_lock-AF_VSOCK);
lock(sk_lock-AF_VSOCK);

*** DEADLOCK ***

May be due to missing lock nesting notation

3 locks held by kworker/1:5/6007:
#0: ffff888112391940 ((wq_completion)vsock-loopback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
#0: ffff888112391940 ((wq_completion)vsock-loopback){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
#1: ffffc900030dfc40 ((work_completion)(&vsock->pkt_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
#1: ffffc900030dfc40 ((work_completion)(&vsock->pkt_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
#2: ffff88817492e2a0 (sk_lock-AF_VSOCK){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#2: ffff88817492e2a0 (sk_lock-AF_VSOCK){+.+.}-{0:0}, at: virtio_transport_recv_pkt+0xfde/0x2bb0 net/vmw_vsock/virtio_transport_common.c:1671

stack backtrace:
CPU: 1 UID: 0 PID: 6007 Comm: kworker/1:5 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: vsock-loopback vsock_loopback_work
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041
check_deadlock kernel/locking/lockdep.c:3093 [inline]
validate_chain kernel/locking/lockdep.c:3895 [inline]
__lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
lock_sock_nested+0x41/0x100 net/core/sock.c:3783
lock_sock include/net/sock.h:1713 [inline]
virtio_transport_recv_listen+0x13a5/0x2230 net/vmw_vsock/virtio_transport_common.c:1593
virtio_transport_recv_pkt+0x174b/0x2bb0 net/vmw_vsock/virtio_transport_common.c:1695
vsock_loopback_work+0x32c/0x3f0 net/vmw_vsock/vsock_loopback.c:142
process_one_work kernel/workqueue.c:3302 [inline]
process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
Tested-by: syz...@syzkaller.appspotmail.com

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