syzbot

======================================================
WARNING: possible circular locking dependency detected
6.9.0-syzkaller-12162-gf85af9d955ac #0 Not tainted
------------------------------------------------------
syz-executor328/5090 is trying to acquire lock:
ffff88801f22e2b0 (&psock->link_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff88801f22e2b0 (&psock->link_lock){+...}-{2:2}, at: sock_map_add_link net/core/sock_map.c:146 [inline]
ffff88801f22e2b0 (&psock->link_lock){+...}-{2:2}, at: sock_map_update_common+0x31c/0x5b0 net/core/sock_map.c:515

but task is already holding lock:
ffff88802aa4fa20 (&stab->lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff88802aa4fa20 (&stab->lock){+.-.}-{2:2}, at: sock_map_update_common+0x1b6/0x5b0 net/core/sock_map.c:505

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&stab->lock){+.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:356 [inline]
       __sock_map_delete net/core/sock_map.c:429 [inline]
       sock_map_delete_elem+0x175/0x250 net/core/sock_map.c:461
       bpf_prog_330576d32f01b34b+0x63/0x67
       bpf_dispatcher_nop_func include/linux/bpf.h:1243 [inline]
       __bpf_prog_run include/linux/filter.h:691 [inline]
       bpf_prog_run include/linux/filter.h:698 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2403 [inline]
       bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2444
       trace_kfree include/trace/events/kmem.h:94 [inline]
       kfree+0x2bb/0x360 mm/slub.c:4544
       sk_psock_free_link include/linux/skmsg.h:423 [inline]
       sock_map_del_link net/core/sock_map.c:170 [inline]
       sock_map_unref+0x3ac/0x5e0 net/core/sock_map.c:192
       sock_hash_update_common+0x915/0xa30 net/core/sock_map.c:1048
       sock_map_update_elem_sys+0x5a4/0x910 net/core/sock_map.c:596
       map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1654
       __sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5697
       __do_sys_bpf kernel/bpf/syscall.c:5816 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5814 [inline]
       __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5814
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&psock->link_lock){+...}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:356 [inline]
       sock_map_add_link net/core/sock_map.c:146 [inline]
       sock_map_update_common+0x31c/0x5b0 net/core/sock_map.c:515
       sock_map_update_elem_sys+0x55f/0x910 net/core/sock_map.c:594
       map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1654
       __sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5697
       __do_sys_bpf kernel/bpf/syscall.c:5816 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5814 [inline]
       __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5814
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

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-executor328/5090:
 #0: ffff8880203c5258 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1602 [inline]
 #0: ffff8880203c5258 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_sk_acquire net/core/sock_map.c:129 [inline]
 #0: ffff8880203c5258 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_update_elem_sys+0x1cc/0x910 net/core/sock_map.c:590
 #1: ffffffff8e333e60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #1: ffffffff8e333e60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #1: ffffffff8e333e60 (rcu_read_lock){....}-{1:2}, at: sock_map_sk_acquire net/core/sock_map.c:130 [inline]
 #1: ffffffff8e333e60 (rcu_read_lock){....}-{1:2}, at: sock_map_update_elem_sys+0x1d8/0x910 net/core/sock_map.c:590
 #2: ffff88802aa4fa20 (&stab->lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #2: ffff88802aa4fa20 (&stab->lock){+.-.}-{2:2}, at: sock_map_update_common+0x1b6/0x5b0 net/core/sock_map.c:505

stack backtrace:
CPU: 1 PID: 5090 Comm: syz-executor328 Not tainted 6.9.0-syzkaller-12162-gf85af9d955ac #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
 _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
 spin_lock_bh include/linux/spinlock.h:356 [inline]
 sock_map_add_link net/core/sock_map.c:146 [inline]
 sock_map_update_common+0x31c/0x5b0 net/core/sock_map.c:515
 sock_map_update_elem_sys+0x55f/0x910 net/core/sock_map.c:594
 map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1654
 __sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5697
 __do_sys_bpf kernel/bpf/syscall.c:5816 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5814 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5814
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f34bd8e71b9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe389a5e98 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f34bd8e71b9
RDX: 0000000000000020 RSI: 00000000200000c0 RDI: 0000000000000002
RBP: 0000000000000000 R08: 0000000000000006 R09: 0000000000000006
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001
 </TASK>