[syzbot] possible deadlock in rfcomm_sk_state_change
From: syzbot
Date: Mon Sep 13 2021 - 01:15:28 EST
Hello,
syzbot found the following issue on:
HEAD commit: a3fa7a101dcf Merge branches 'akpm' and 'akpm-hotfixes' (pa..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10d61a8b300000
kernel config: https://syzkaller.appspot.com/x/.config?x=a9b60f3b657f313d
dashboard link: https://syzkaller.appspot.com/bug?extid=d7ce59b06b3eb14fd218
compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15247a7d300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12a2642b300000
The issue was bisected to:
commit 1804fdf6e494e5e2938c65d8391690b59bcff897
Author: Tedd Ho-Jeong An <tedd.an@xxxxxxxxx>
Date: Thu Aug 5 00:32:19 2021 +0000
Bluetooth: btintel: Combine setting up MSFT extension
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=125f4163300000
final oops: https://syzkaller.appspot.com/x/report.txt?x=115f4163300000
console output: https://syzkaller.appspot.com/x/log.txt?x=165f4163300000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d7ce59b06b3eb14fd218@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 1804fdf6e494 ("Bluetooth: btintel: Combine setting up MSFT extension")
======================================================
WARNING: possible circular locking dependency detected
5.14.0-syzkaller #0 Not tainted
------------------------------------------------------
krfcommd/2875 is trying to acquire lock:
ffff888012b9d120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1612 [inline]
ffff888012b9d120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sk_state_change+0x63/0x300 net/bluetooth/rfcomm/sock.c:73
but task is already holding lock:
ffff88807cf12528 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x281/0x480 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){+.+.}-{3:3}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625
__mutex_lock_common+0x1df/0x2550 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:743
__rfcomm_dlc_close+0x281/0x480 net/bluetooth/rfcomm/core.c:487
rfcomm_process_dlcs+0x92/0x620 net/bluetooth/rfcomm/core.c:1844
rfcomm_process_sessions+0x2f6/0x3f0 net/bluetooth/rfcomm/core.c:2003
rfcomm_run+0x195/0x2c0 net/bluetooth/rfcomm/core.c:2086
kthread+0x453/0x480 kernel/kthread.c:319
ret_from_fork+0x1f/0x30
-> #1 (rfcomm_mutex){+.+.}-{3:3}:
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625
__mutex_lock_common+0x1df/0x2550 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:743
rfcomm_dlc_open+0x25/0x50 net/bluetooth/rfcomm/core.c:425
rfcomm_sock_connect+0x285/0x470 net/bluetooth/rfcomm/sock.c:413
__sys_connect_file net/socket.c:1896 [inline]
__sys_connect+0x38a/0x410 net/socket.c:1913
__do_sys_connect net/socket.c:1923 [inline]
__se_sys_connect net/socket.c:1920 [inline]
__x64_sys_connect+0x76/0x80 net/socket.c:1920
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3051 [inline]
check_prevs_add kernel/locking/lockdep.c:3174 [inline]
validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3789
__lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5015
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625
lock_sock_nested+0xc6/0x110 net/core/sock.c:3191
lock_sock include/net/sock.h:1612 [inline]
rfcomm_sk_state_change+0x63/0x300 net/bluetooth/rfcomm/sock.c:73
__rfcomm_dlc_close+0x2cc/0x480 net/bluetooth/rfcomm/core.c:489
rfcomm_process_dlcs+0x92/0x620 net/bluetooth/rfcomm/core.c:1844
rfcomm_process_sessions+0x2f6/0x3f0 net/bluetooth/rfcomm/core.c:2003
rfcomm_run+0x195/0x2c0 net/bluetooth/rfcomm/core.c:2086
kthread+0x453/0x480 kernel/kthread.c:319
ret_from_fork+0x1f/0x30
other info that might help us debug this:
Chain exists of:
sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM --> rfcomm_mutex --> &d->lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&d->lock);
lock(rfcomm_mutex);
lock(&d->lock);
lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM);
*** DEADLOCK ***
2 locks held by krfcommd/2875:
#0: ffffffff8dac7488 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_process_sessions+0x21/0x3f0 net/bluetooth/rfcomm/core.c:1979
#1: ffff88807cf12528 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x281/0x480 net/bluetooth/rfcomm/core.c:487
stack backtrace:
CPU: 1 PID: 2875 Comm: krfcommd Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1dc/0x2d8 lib/dump_stack.c:106
check_noncircular+0x2f9/0x3b0 kernel/locking/lockdep.c:2131
check_prev_add kernel/locking/lockdep.c:3051 [inline]
check_prevs_add kernel/locking/lockdep.c:3174 [inline]
validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3789
__lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5015
lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625
lock_sock_nested+0xc6/0x110 net/core/sock.c:3191
lock_sock include/net/sock.h:1612 [inline]
rfcomm_sk_state_change+0x63/0x300 net/bluetooth/rfcomm/sock.c:73
__rfcomm_dlc_close+0x2cc/0x480 net/bluetooth/rfcomm/core.c:489
rfcomm_process_dlcs+0x92/0x620 net/bluetooth/rfcomm/core.c:1844
rfcomm_process_sessions+0x2f6/0x3f0 net/bluetooth/rfcomm/core.c:2003
rfcomm_run+0x195/0x2c0 net/bluetooth/rfcomm/core.c:2086
kthread+0x453/0x480 kernel/kthread.c:319
ret_from_fork+0x1f/0x30
---
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