[v5.15] possible deadlock in sock_map_update_common

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cdfd0a7f0139 Linux 5.15.154
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17de3b4d180000
kernel config: https://syzkaller.appspot.com/x/.config?x=618bf6f66d00ead6
dashboard link: https://syzkaller.appspot.com/bug?extid=f64311c8c313b19f4b96
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15a71b6d180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=136ab493180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1e2563577ef3/disk-cdfd0a7f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5b2e7461a373/vmlinux-cdfd0a7f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6026a13e03b8/bzImage-cdfd0a7f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f64311...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.15.154-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor111/3499 is trying to acquire lock:
ffff888147a1e290 (&psock->link_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
ffff888147a1e290 (&psock->link_lock){+...}-{2:2}, at: sock_map_add_link net/core/sock_map.c:136 [inline]
ffff888147a1e290 (&psock->link_lock){+...}-{2:2}, at: sock_map_update_common+0x31c/0x5b0 net/core/sock_map.c:505

but task is already holding lock:
ffff888022579dc0 (&stab->lock){+...}-{2:2}, at: sock_map_update_common+0x1b6/0x5b0 net/core/sock_map.c:495

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&stab->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_map_delete net/core/sock_map.c:419 [inline]
sock_map_delete_elem+0x161/0x230 net/core/sock_map.c:451
bpf_prog_9d96c76a008f5a1e+0x5b/0x1e4
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
sk_psock_free_link include/linux/skmsg.h:422 [inline]
sock_map_del_link net/core/sock_map.c:160 [inline]
sock_map_unref+0x3ac/0x5d0 net/core/sock_map.c:182
sock_hash_delete_elem+0x388/0x400 net/core/sock_map.c:947
map_delete_elem+0x431/0x580 kernel/bpf/syscall.c:1239
__sys_bpf+0x311/0x670 kernel/bpf/syscall.c:4642
__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+0x3b/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&psock->link_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]
sock_map_add_link net/core/sock_map.c:136 [inline]
sock_map_update_common+0x31c/0x5b0 net/core/sock_map.c:505
sock_map_update_elem_sys+0x440/0x770 net/core/sock_map.c:588
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+0x3b/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&stab->lock);
lock(&psock->link_lock);
lock(&stab->lock);
lock(&psock->link_lock);

*** DEADLOCK ***

3 locks held by syz-executor111/3499:
#0: ffff88801eafa120 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1668 [inline]
#0: ffff88801eafa120 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_sk_acquire net/core/sock_map.c:119 [inline]
#0: ffff88801eafa120 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_update_elem_sys+0x1c8/0x770 net/core/sock_map.c:584
#1: ffffffff8c91fae0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
#2: ffff888022579dc0 (&stab->lock){+...}-{2:2}, at: sock_map_update_common+0x1b6/0x5b0 net/core/sock_map.c:495

stack backtrace:
CPU: 0 PID: 3499 Comm: syz-executor111 Not tainted 5.15.154-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+0x1e3/0x2d0 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]
sock_map_add_link net/core/sock_map.c:136 [inline]
sock_map_update_common+0x31c/0x5b0 net/core/sock_map.c:505
sock_map_update_elem_sys+0x440/0x770 net/core/sock_map.c:588
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+0x3b/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1677352a29
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffff84eabb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007ffff84ead88 RCX: 00007f1677352a29
RDX: 0000000000000020 RSI: 00000000200000c0 RDI: 0000000000000002
RBP: 00007f16773c6610 R08: 00007ffff84ead88 R09: 00007ffff84ead88
R10: 00007ffff84ead88 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffff84ead78 R


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