[v5.15] possible deadlock in sk_psock_stop

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9465fef4ae35 Linux 5.15.153
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14887623180000
kernel config: https://syzkaller.appspot.com/x/.config?x=176c746ee3348b33
dashboard link: https://syzkaller.appspot.com/bug?extid=e69c6393efd5d9fdfb96
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/741f29d5f449/disk-9465fef4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/66645f341114/vmlinux-9465fef4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f7d21e0c9e19/bzImage-9465fef4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e69c63...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.15.153-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/6900 is trying to acquire lock:
ffff8880234a4238 (&psock->ingress_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
ffff8880234a4238 (&psock->ingress_lock){+...}-{2:2}, at: sk_psock_stop+0x31/0x4c0 net/core/skmsg.c:802

but task is already holding lock:
ffff88805bb9fd20 (&htab->buckets[i].lock){+.-.}-{2:2}, at: sock_hash_update_common+0x20c/0xa30 net/core/sock_map.c:1005

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&htab->buckets[i].lock){+.-.}-{2:2}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
sock_hash_delete_elem+0xac/0x2f0 net/core/sock_map.c:937
0xffffffffa00188aa
bpf_dispatcher_nop_func include/linux/bpf.h:785 [inline]
__bpf_prog_run include/linux/filter.h:628 [inline]
bpf_prog_run include/linux/filter.h:635 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:1880 [inline]
bpf_trace_run2+0x19e/0x340 kernel/trace/bpf_trace.c:1917
__bpf_trace_kfree+0x6e/0x90 include/trace/events/kmem.h:118
trace_kfree include/trace/events/kmem.h:118 [inline]
kfree+0x22f/0x270 mm/slub.c:4549
skb_free_head net/core/skbuff.c:655 [inline]
skb_release_data+0x73a/0x8a0 net/core/skbuff.c:677
skb_release_all net/core/skbuff.c:742 [inline]
__kfree_skb net/core/skbuff.c:756 [inline]
consume_skb+0xa3/0x140 net/core/skbuff.c:914
__sk_msg_free+0x2cd/0x350 net/core/skmsg.c:205
sk_msg_free net/core/skmsg.c:218 [inline]
__sk_psock_purge_ingress_msg net/core/skmsg.c:769 [inline]
__sk_psock_zap_ingress net/core/skmsg.c:787 [inline]
sk_psock_stop+0x44c/0x4c0 net/core/skmsg.c:805
sock_map_close+0x17c/0x290 net/core/sock_map.c:1572
unix_release+0x7e/0xc0 net/unix/af_unix.c:949
__sock_release net/socket.c:649 [inline]
sock_close+0xcd/0x230 net/socket.c:1336
__fput+0x3bf/0x890 fs/file_table.c:280
task_work_run+0x129/0x1a0 kernel/task_work.c:164
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x106/0x130 kernel/entry/common.c:175
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x5d/0x250 kernel/entry/common.c:301
do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x61/0xcb

-> #0 (&psock->ingress_lock){+...}-{2:2}:
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788
__lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:368 [inline]
sk_psock_stop+0x31/0x4c0 net/core/skmsg.c:802
sk_psock_drop+0x2aa/0x3b0 net/core/skmsg.c:844
sock_hash_update_common+0x911/0xa30 net/core/sock_map.c:1028
sock_map_update_elem_sys+0x485/0x770 net/core/sock_map.c:587
map_update_elem+0x6a0/0x7c0 kernel/bpf/syscall.c:1185
__sys_bpf+0x2fd/0x670 kernel/bpf/syscall.c:4639
__do_sys_bpf kernel/bpf/syscall.c:4755 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4753 [inline]
__x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4753
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&htab->buckets[i].lock);
lock(&psock->ingress_lock);
lock(&htab->buckets[i].lock);
lock(&psock->ingress_lock);

*** DEADLOCK ***

3 locks held by syz-executor.4/6900:
#0: ffff888022b47920 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1668 [inline]
#0: ffff888022b47920 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_sk_acquire net/core/sock_map.c:119 [inline]
#0: ffff888022b47920 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_update_elem_sys+0x1c8/0x770 net/core/sock_map.c:581
#1: ffffffff8c91f720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
#2: ffff88805bb9fd20 (&htab->buckets[i].lock){+.-.}-{2:2}, at: sock_hash_update_common+0x20c/0xa30 net/core/sock_map.c:1005

stack backtrace:
CPU: 0 PID: 6900 Comm: syz-executor.4 Not tainted 5.15.153-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
check_noncircular+0x2f8/0x3b0 kernel/locking/lockdep.c:2133
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788
__lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:368 [inline]
sk_psock_stop+0x31/0x4c0 net/core/skmsg.c:802
sk_psock_drop+0x2aa/0x3b0 net/core/skmsg.c:844
sock_hash_update_common+0x911/0xa30 net/core/sock_map.c:1028
sock_map_update_elem_sys+0x485/0x770 net/core/sock_map.c:587
map_update_elem+0x6a0/0x7c0 kernel/bpf/syscall.c:1185
__sys_bpf+0x2fd/0x670 kernel/bpf/syscall.c:4639
__do_sys_bpf kernel/bpf/syscall.c:4755 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4753 [inline]
__x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4753
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fe983b06e69
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe9820790c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fe983c34f80 RCX: 00007fe983b06e69
RDX: 0000000000000020 RSI: 00000000200004c0 RDI: 0000000000000002
RBP: 00007fe983b5347a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fe983c34f80 R15: 00007fffc6dfd808
</TASK>


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