BUG: soft lockup in hci_sock_release

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 66722c42ec91 Linux 4.14.256
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14d8ce3ab00000
kernel config: https://syzkaller.appspot.com/x/.config?x=b8004ce84f364d9
dashboard link: https://syzkaller.appspot.com/bug?extid=dbc31e9e4bd901a05adc
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dbc31e...@syzkaller.appspotmail.com

watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [syz-executor.4:13654]
Modules linked in:
irq event stamp: 9530
hardirqs last enabled at (9529): [<ffffffff87400976>] restore_regs_and_return_to_kernel+0x0/0x2a
hardirqs last disabled at (9530): [<ffffffff874018ae>] apic_timer_interrupt+0x8e/0xa0 arch/x86/entry/entry_64.S:793
softirqs last enabled at (4856): [<ffffffff8760068b>] __do_softirq+0x68b/0x9ff kernel/softirq.c:314
softirqs last disabled at (4495): [<ffffffff81321d13>] invoke_softirq kernel/softirq.c:368 [inline]
softirqs last disabled at (4495): [<ffffffff81321d13>] irq_exit+0x193/0x240 kernel/softirq.c:409
CPU: 0 PID: 13654 Comm: syz-executor.4 Not tainted 4.14.256-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88808d4ae140 task.stack: ffff888063d20000
RIP: 0010:__read_once_size include/linux/compiler.h:185 [inline]
RIP: 0010:atomic_read arch/x86/include/asm/atomic.h:27 [inline]
RIP: 0010:queued_write_lock_slowpath+0xcb/0x1d0 kernel/locking/qrwlock.c:139
RSP: 0018:ffff888063d27d10 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff10
RAX: 0000000000000101 RBX: ffffffff89dd63a8 RCX: 00000000000033b5
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff89dd63a8
RBP: ffffffff89dd63ac R08: ffffffff8b9b7868 R09: 000000000004059e
R10: ffff88808d4aea18 R11: ffff88808d4ae140 R12: 0000000000000003
R13: fffffbfff13bac75 R14: 00000000000000ff R15: ffff88809c1b5050
FS: 0000555555bbc400(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f922000 CR3: 00000000b076e000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
queued_write_lock include/asm-generic/qrwlock.h:134 [inline]
do_raw_write_lock+0xc2/0x1d0 kernel/locking/spinlock_debug.c:203
bt_sock_unlink+0x1d/0x170 net/bluetooth/af_bluetooth.c:151
hci_sock_release+0xc1/0x4c0 net/bluetooth/hci_sock.c:855
__sock_release+0xcd/0x2b0 net/socket.c:602
sock_close+0x15/0x20 net/socket.c:1139
__fput+0x25f/0x7a0 fs/file_table.c:210
task_work_run+0x11f/0x190 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7fb5d963272b
RSP: 002b:00007ffc788a28f0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 00007fb5d963272b
RDX: ffffffffffffffbc RSI: ffffffff8740008a RDI: 0000000000000004
RBP: 0000000000000005 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000419 R11: 0000000000000293 R12: 00007fb5d9792f60
R13: 0000000000024578 R14: 0000000000000000 R15: 0000000000024570
Code: 75 dc 49 89 dd 49 89 dc 41 be ff 00 00 00 49 c1 ed 03 41 83 e4 07 48 b8 00 00 00 00 00 fc ff df 49 01 c5 41 83 c4 03 eb 02 f3 90 <41> 0f b6 45 00 41 38 c4 7c 08 84 c0 0f 85 9e 00 00 00 8b 03 83
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff8723c75e
----------------
Code disassembly (best guess):
0: 75 dc jne 0xffffffde
2: 49 89 dd mov %rbx,%r13
5: 49 89 dc mov %rbx,%r12
8: 41 be ff 00 00 00 mov $0xff,%r14d
e: 49 c1 ed 03 shr $0x3,%r13
12: 41 83 e4 07 and $0x7,%r12d
16: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
1d: fc ff df
20: 49 01 c5 add %rax,%r13
23: 41 83 c4 03 add $0x3,%r12d
27: eb 02 jmp 0x2b
29: f3 90 pause
* 2b: 41 0f b6 45 00 movzbl 0x0(%r13),%eax <-- trapping instruction
30: 41 38 c4 cmp %al,%r12b
33: 7c 08 jl 0x3d
35: 84 c0 test %al,%al
37: 0f 85 9e 00 00 00 jne 0xdb
3d: 8b 03 mov (%rbx),%eax
3f: 83 .byte 0x83


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.