syzbot

======================================================
WARNING: possible circular locking dependency detected
5.15.167-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.352/5268 is trying to acquire lock:
ffff88801bbc6120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM#2){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1676 [inline]
ffff88801bbc6120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM#2){+.+.}-{0:0}, at: rfcomm_sk_state_change+0x57/0x300 net/bluetooth/rfcomm/sock.c:73

but task is already holding lock:
ffff888062009128 (&d->lock#2){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x259/0x6d0 net/bluetooth/rfcomm/core.c:487

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&d->lock#2){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       __rfcomm_dev_add net/bluetooth/rfcomm/tty.c:278 [inline]
       rfcomm_dev_add net/bluetooth/rfcomm/tty.c:326 [inline]
       __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:425 [inline]
       rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline]
       rfcomm_dev_ioctl+0x14f8/0x2180 net/bluetooth/rfcomm/tty.c:588
       rfcomm_sock_ioctl+0x82/0xc0 net/bluetooth/rfcomm/sock.c:880
       sock_do_ioctl+0x11d/0x5a0 net/socket.c:1140
       sock_ioctl+0x47f/0x770 net/socket.c:1257
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
       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

-> #1 (rfcomm_dev_lock){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       rfcomm_dev_get+0x7d/0x380 net/bluetooth/rfcomm/tty.c:164
       rfcomm_get_dev_info net/bluetooth/rfcomm/tty.c:565 [inline]
       rfcomm_dev_ioctl+0x29d/0x2180 net/bluetooth/rfcomm/tty.c:597
       rfcomm_sock_ioctl+0x82/0xc0 net/bluetooth/rfcomm/sock.c:880
       sock_do_ioctl+0x11d/0x5a0 net/socket.c:1140
       sock_ioctl+0x47f/0x770 net/socket.c:1257
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
       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 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM#2){+.+.}-{0:0}:
       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
       lock_sock_nested+0x44/0x100 net/core/sock.c:3250
       lock_sock include/net/sock.h:1676 [inline]
       rfcomm_sk_state_change+0x57/0x300 net/bluetooth/rfcomm/sock.c:73
       __rfcomm_dlc_close+0x2b2/0x6d0 net/bluetooth/rfcomm/core.c:489
       rfcomm_dlc_close+0xed/0x180 net/bluetooth/rfcomm/core.c:520
       __rfcomm_sock_close+0x104/0x220 net/bluetooth/rfcomm/sock.c:220
       rfcomm_sock_shutdown+0xb4/0x230 net/bluetooth/rfcomm/sock.c:912
       __sys_shutdown_sock net/socket.c:2270 [inline]
       __sys_shutdown net/socket.c:2282 [inline]
       __do_sys_shutdown net/socket.c:2290 [inline]
       __se_sys_shutdown+0x147/0x1a0 net/socket.c:2288
       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:

Chain exists of:
  sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM#2 --> rfcomm_dev_lock --> &d->lock#2

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&d->lock#2);
                               lock(rfcomm_dev_lock);
                               lock(&d->lock#2);
  lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM#2);

 *** DEADLOCK ***

2 locks held by syz.0.352/5268:
 #0: ffffffff8db9a628 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_close+0x37/0x180 net/bluetooth/rfcomm/core.c:507
 #1: ffff888062009128 (&d->lock#2){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x259/0x6d0 net/bluetooth/rfcomm/core.c:487

stack backtrace:
CPU: 1 PID: 5268 Comm: syz.0.352 Not tainted 5.15.167-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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
 lock_sock_nested+0x44/0x100 net/core/sock.c:3250
 lock_sock include/net/sock.h:1676 [inline]
 rfcomm_sk_state_change+0x57/0x300 net/bluetooth/rfcomm/sock.c:73
 __rfcomm_dlc_close+0x2b2/0x6d0 net/bluetooth/rfcomm/core.c:489
 rfcomm_dlc_close+0xed/0x180 net/bluetooth/rfcomm/core.c:520
 __rfcomm_sock_close+0x104/0x220 net/bluetooth/rfcomm/sock.c:220
 rfcomm_sock_shutdown+0xb4/0x230 net/bluetooth/rfcomm/sock.c:912
 __sys_shutdown_sock net/socket.c:2270 [inline]
 __sys_shutdown net/socket.c:2282 [inline]
 __do_sys_shutdown net/socket.c:2290 [inline]
 __se_sys_shutdown+0x147/0x1a0 net/socket.c:2288
 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: 0033:0x7f780494eff9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7802da6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000030
RAX: ffffffffffffffda RBX: 00007f7804b07058 RCX: 00007f780494eff9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f78049c1296 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f7804b07058 R15: 00007ffe7c7c31c8
 </TASK>