syzbot has found a reproducer for the following issue on: HEAD commit: a6d9e3034536 Add linux-next specific files for 20230330 git tree: linux-next console+strace: https://syzkaller.appspot.com/x/log.txt?x=152adc3ec80000 kernel config: https://syzkaller.appspot.com/x/.config?x=aceb117f7924508e dashboard link: https://syzkaller.appspot.com/bug?extid=b69a625d06e8ece26415 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=153acb85c80000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=179d1ed1c80000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/ec1f900ea929/disk-a6d9e303.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/fabbf89c0d22/vmlinux-a6d9e303.xz kernel image: https://storage.googleapis.com/syzbot-assets/1ed05d6192fa/bzImage-a6d9e303.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+b69a625d06e8ece26415@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 6.3.0-rc4-next-20230330-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor363/5115 is trying to acquire lock: ffffffff8e357cc8 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_exists+0x58/0x190 net/bluetooth/rfcomm/core.c:546 but task is already holding lock: ffffffff8e35cc88 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline] ffffffff8e35cc88 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x8a2/0x1c00 net/bluetooth/rfcomm/tty.c:587 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 kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747 rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline] rfcomm_dev_ioctl+0x8a2/0x1c00 net/bluetooth/rfcomm/tty.c:587 rfcomm_sock_ioctl+0xb7/0xe0 net/bluetooth/rfcomm/sock.c:880 sock_do_ioctl+0xcc/0x230 net/socket.c:1199 sock_ioctl+0x1f8/0x680 net/socket.c:1316 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #2 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}: lock_sock_nested+0x3a/0xf0 net/core/sock.c:3474 lock_sock include/net/sock.h:1697 [inline] rfcomm_sk_state_change+0x6d/0x3a0 net/bluetooth/rfcomm/sock.c:73 __rfcomm_dlc_close+0x1b1/0x890 net/bluetooth/rfcomm/core.c:493 rfcomm_dlc_close+0x1e9/0x240 net/bluetooth/rfcomm/core.c:524 __rfcomm_sock_close+0x17a/0x2f0 net/bluetooth/rfcomm/sock.c:220 rfcomm_sock_shutdown+0xd8/0x230 net/bluetooth/rfcomm/sock.c:912 rfcomm_sock_release+0x68/0x140 net/bluetooth/rfcomm/sock.c:933 __sock_release+0xcd/0x290 net/socket.c:653 sock_close+0x1c/0x20 net/socket.c:1395 __fput+0x27c/0xa90 fs/file_table.c:321 task_work_run+0x16f/0x270 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xb0d/0x29f0 kernel/exit.c:869 do_group_exit+0xd4/0x2a0 kernel/exit.c:1019 get_signal+0x2315/0x25b0 kernel/signal.c:2859 arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:307 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #1 (&d->lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747 __rfcomm_dlc_close+0x15d/0x890 net/bluetooth/rfcomm/core.c:491 rfcomm_dlc_close+0x1e9/0x240 net/bluetooth/rfcomm/core.c:524 __rfcomm_sock_close+0x17a/0x2f0 net/bluetooth/rfcomm/sock.c:220 rfcomm_sock_shutdown+0xd8/0x230 net/bluetooth/rfcomm/sock.c:912 rfcomm_sock_release+0x68/0x140 net/bluetooth/rfcomm/sock.c:933 __sock_release+0xcd/0x290 net/socket.c:653 sock_close+0x1c/0x20 net/socket.c:1395 __fput+0x27c/0xa90 fs/file_table.c:321 task_work_run+0x16f/0x270 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xb0d/0x29f0 kernel/exit.c:869 do_group_exit+0xd4/0x2a0 kernel/exit.c:1019 get_signal+0x2315/0x25b0 kernel/signal.c:2859 arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:307 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #0 (rfcomm_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3108 [inline] check_prevs_add kernel/locking/lockdep.c:3227 [inline] validate_chain kernel/locking/lockdep.c:3842 [inline] __lock_acquire+0x2f21/0x5df0 kernel/locking/lockdep.c:5074 lock_acquire.part.0+0x11c/0x370 kernel/locking/lockdep.c:5691 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747 rfcomm_dlc_exists+0x58/0x190 net/bluetooth/rfcomm/core.c:546 __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:414 [inline] rfcomm_create_dev net/bluetooth/rfcomm/tty.c:485 [inline] rfcomm_dev_ioctl+0x966/0x1c00 net/bluetooth/rfcomm/tty.c:587 rfcomm_sock_ioctl+0xb7/0xe0 net/bluetooth/rfcomm/sock.c:880 sock_do_ioctl+0xcc/0x230 net/socket.c:1199 sock_ioctl+0x1f8/0x680 net/socket.c:1316 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd 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-executor363/5115: #0: ffff888146eb7130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1697 [inline] #0: ffff888146eb7130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_ioctl+0xaa/0xe0 net/bluetooth/rfcomm/sock.c:879 #1: ffffffff8e35cc88 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline] #1: ffffffff8e35cc88 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x8a2/0x1c00 net/bluetooth/rfcomm/tty.c:587 stack backtrace: CPU: 0 PID: 5115 Comm: syz-executor363 Not tainted 6.3.0-rc4-next-20230330-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2188 check_prev_add kernel/locking/lockdep.c:3108 [inline] check_prevs_add kernel/locking/lockdep.c:3227 [inline] validate_chain kernel/locking/lockdep.c:3842 [inline] __lock_acquire+0x2f21/0x5df0 kernel/locking/lockdep.c:5074 lock_acquire.part.0+0x11c/0x370 kernel/locking/lockdep.c:5691 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747 rfcomm_dlc_exists+0x58/0x190 net/bluetooth/rfcomm/core.c:546 __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:414 [inline] rfcomm_create_dev net/bluetooth/rfcomm/tty.c:485 [inline] rfcomm_dev_ioctl+0x966/0x1c00 net/bluetooth/rfcomm/tty.c:587 rfcomm_sock_ioctl+0xb7/0xe0 net/bluetooth/rfcomm/sock.c:880 sock_do_ioctl+0xcc/0x230 net/socket.c:1199 sock_ioctl+0x1f8/0x680 net/socket.c:1316 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fdd90dc3379 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 d1 15 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:00007ffc287c58b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fdd90dc3379 RDX: 0000000020000100 RSI: 00000000400452c8 RDI: 0000000000000006 RBP: 0000000000000000 R08: 0000000000000000 R09: 00007ffc287c58e8 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc287c5900 R13: 00007ffc287c5910 R14: 000000000001c039 R15: 00007ffc287c58d0 </TASK>
