syzbot has found a reproducer for the following issue on:
HEAD commit: c52b9710c83d Linux 5.15.156
git tree: linux-5.15.y
console output:
https://syzkaller.appspot.com/x/log.txt?x=119e4bf7180000
kernel config:
https://syzkaller.appspot.com/x/.config?x=41e09ec50c6bb4e4
dashboard link:
https://syzkaller.appspot.com/bug?extid=de82738425bd819f2b1e
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro:
https://syzkaller.appspot.com/x/repro.syz?x=139a83fd180000
C reproducer:
https://syzkaller.appspot.com/x/repro.c?x=12ff5ae7180000
Downloadable assets:
disk image:
https://storage.googleapis.com/syzbot-assets/586695cf1548/disk-c52b9710.raw.xz
vmlinux:
https://storage.googleapis.com/syzbot-assets/10a68b27874f/vmlinux-c52b9710.xz
kernel image:
https://storage.googleapis.com/syzbot-assets/610e1be513a8/Image-c52b9710.gz.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by:
syzbot+de8273...@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
5.15.156-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor281/3988 is trying to acquire lock:
ffff800016b98b68 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_exists+0xb0/0x32c net/bluetooth/rfcomm/core.c:542
but task is already holding lock:
ffff800016b9c4c8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:485 [inline]
ffff800016b9c4c8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x258/0x2434 net/bluetooth/rfcomm/tty.c:588
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (rfcomm_ioctl_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
rfcomm_create_dev net/bluetooth/rfcomm/tty.c:485 [inline]
rfcomm_dev_ioctl+0x258/0x2434 net/bluetooth/rfcomm/tty.c:588
rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:880
sock_do_ioctl+0x134/0x2dc net/socket.c:1140
sock_ioctl+0x4f0/0x8ac net/socket.c:1257
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
-> #2 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}:
lock_sock_nested+0xec/0x1ec net/core/sock.c:3250
lock_sock include/net/sock.h:1668 [inline]
rfcomm_sk_state_change+0x60/0x2c8 net/bluetooth/rfcomm/sock.c:73
__rfcomm_dlc_close+0x23c/0x634 net/bluetooth/rfcomm/core.c:489
rfcomm_dlc_close+0x100/0x194 net/bluetooth/rfcomm/core.c:520
__rfcomm_sock_close+0x138/0x258 net/bluetooth/rfcomm/sock.c:220
rfcomm_sock_shutdown+0xa8/0x214 net/bluetooth/rfcomm/sock.c:912
rfcomm_sock_release+0x58/0x114 net/bluetooth/rfcomm/sock.c:933
__sock_release net/socket.c:649 [inline]
sock_close+0xb8/0x1fc net/socket.c:1336
__fput+0x30c/0x7f0 fs/file_table.c:280
____fput+0x20/0x30 fs/file_table.c:308
task_work_run+0x130/0x1e4 kernel/task_work.c:164
exit_task_work include/linux/task_work.h:32 [inline]
do_exit+0x670/0x20bc kernel/exit.c:872
do_group_exit+0x110/0x268 kernel/exit.c:994
get_signal+0x634/0x1550 kernel/signal.c:2889
do_signal arch/arm64/kernel/signal.c:890 [inline]
do_notify_resume+0x3d0/0x32b8 arch/arm64/kernel/signal.c:943
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
el0_svc+0xfc/0x1f0 arch/arm64/kernel/entry-common.c:609
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
-> #1 (&d->lock){+.+.}-{3:3}:
__mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
__rfcomm_dlc_close+0x200/0x634 net/bluetooth/rfcomm/core.c:487
rfcomm_dlc_close+0x100/0x194 net/bluetooth/rfcomm/core.c:520
__rfcomm_sock_close+0x138/0x258 net/bluetooth/rfcomm/sock.c:220
rfcomm_sock_shutdown+0xa8/0x214 net/bluetooth/rfcomm/sock.c:912
rfcomm_sock_release+0x58/0x114 net/bluetooth/rfcomm/sock.c:933
__sock_release net/socket.c:649 [inline]
sock_close+0xb8/0x1fc net/socket.c:1336
__fput+0x30c/0x7f0 fs/file_table.c:280
____fput+0x20/0x30 fs/file_table.c:308
task_work_run+0x130/0x1e4 kernel/task_work.c:164
exit_task_work include/linux/task_work.h:32 [inline]
do_exit+0x670/0x20bc kernel/exit.c:872
do_group_exit+0x110/0x268 kernel/exit.c:994
get_signal+0x634/0x1550 kernel/signal.c:2889
do_signal arch/arm64/kernel/signal.c:890 [inline]
do_notify_resume+0x3d0/0x32b8 arch/arm64/kernel/signal.c:943
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
el0_svc+0xfc/0x1f0 arch/arm64/kernel/entry-common.c:609
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
-> #0 (rfcomm_mutex){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3788 [inline]
__lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
__mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
rfcomm_dlc_exists+0xb0/0x32c net/bluetooth/rfcomm/core.c:542
__rfcomm_create_dev net/bluetooth/rfcomm/tty.c:415 [inline]
rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline]
rfcomm_dev_ioctl+0x938/0x2434 net/bluetooth/rfcomm/tty.c:588
rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:880
sock_do_ioctl+0x134/0x2dc net/socket.c:1140
sock_ioctl+0x4f0/0x8ac net/socket.c:1257
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
other info that might help us debug this:
Chain exists of:
rfcomm_mutex --> sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM --> rfcomm_ioctl_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(rfcomm_ioctl_mutex);
lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM);
lock(rfcomm_ioctl_mutex);
lock(rfcomm_mutex);
*** DEADLOCK ***
2 locks held by syz-executor281/3988:
#0: ffff0000dd41b120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1668 [inline]
#0: ffff0000dd41b120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_ioctl+0x88/0xf0 net/bluetooth/rfcomm/sock.c:879
#1: ffff800016b9c4c8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:485 [inline]
#1: ffff800016b9c4c8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x258/0x2434 net/bluetooth/rfcomm/tty.c:588
stack backtrace:
CPU: 0 PID: 3988 Comm: syz-executor281 Not tainted 5.15.156-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call trace:
dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011
check_noncircular+0x2cc/0x378 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 kernel/locking/lockdep.c:3788 [inline]
__lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
__mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
rfcomm_dlc_exists+0xb0/0x32c net/bluetooth/rfcomm/core.c:542
__rfcomm_create_dev net/bluetooth/rfcomm/tty.c:415 [inline]
rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline]
rfcomm_dev_ioctl+0x938/0x2434 net/bluetooth/rfcomm/tty.c:588
rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:880
sock_do_ioctl+0x134/0x2dc net/socket.c:1140
sock_ioctl+0x4f0/0x8ac net/socket.c:1257
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
---
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#syz test: git://repo/address.git branch-or-commit-hash
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