====================================================== WARNING: possible circular locking dependency detected 6.9.0-rc6-syzkaller-00046-g18daea77cca6 #0 Not tainted ------------------------------------------------------ syz-executor.3/7638 is trying to acquire lock: ffffffff8f575188 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_exists+0x5f/0x1a0 net/bluetooth/rfcomm/core.c:546 but task is already holding lock: ffffffff8f57a148 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline] ffffffff8f57a148 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x993/0x1e30 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:608 [inline] __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752 rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline] rfcomm_dev_ioctl+0x993/0x1e30 net/bluetooth/rfcomm/tty.c:587 rfcomm_sock_ioctl net/bluetooth/rfcomm/sock.c:869 [inline] rfcomm_sock_compat_ioctl+0xba/0xe0 net/bluetooth/rfcomm/sock.c:882 compat_sock_ioctl+0x181/0x7f0 net/socket.c:3521 __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1004 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #2 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}: lock_sock_nested+0x3a/0xf0 net/core/sock.c:3535 lock_sock include/net/sock.h:1673 [inline] rfcomm_sk_state_change+0x6d/0x3b0 net/bluetooth/rfcomm/sock.c:73 __rfcomm_dlc_close+0x28c/0x720 net/bluetooth/rfcomm/core.c:493 rfcomm_dlc_close+0x1eb/0x240 net/bluetooth/rfcomm/core.c:524 __rfcomm_sock_close+0xa7/0x230 net/bluetooth/rfcomm/sock.c:220 rfcomm_sock_shutdown+0xd5/0x230 net/bluetooth/rfcomm/sock.c:901 rfcomm_sock_release+0x5d/0x140 net/bluetooth/rfcomm/sock.c:922 __sock_release+0xb0/0x270 net/socket.c:659 sock_close+0x1c/0x30 net/socket.c:1421 __fput+0x270/0xb80 fs/file_table.c:422 task_work_run+0x14e/0x250 kernel/task_work.c:180 get_signal+0x1d3/0x2670 kernel/signal.c:2683 arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x14a/0x2a0 kernel/entry/common.c:218 __do_fast_syscall_32+0x82/0x120 arch/x86/entry/common.c:389 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #1 (&d->lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752 __rfcomm_dlc_close+0x235/0x720 net/bluetooth/rfcomm/core.c:491 rfcomm_dlc_close+0x1eb/0x240 net/bluetooth/rfcomm/core.c:524 __rfcomm_sock_close+0xa7/0x230 net/bluetooth/rfcomm/sock.c:220 rfcomm_sock_shutdown+0xd5/0x230 net/bluetooth/rfcomm/sock.c:901 rfcomm_sock_release+0x5d/0x140 net/bluetooth/rfcomm/sock.c:922 __sock_release+0xb0/0x270 net/socket.c:659 sock_close+0x1c/0x30 net/socket.c:1421 __fput+0x270/0xb80 fs/file_table.c:422 task_work_run+0x14e/0x250 kernel/task_work.c:180 get_signal+0x1d3/0x2670 kernel/signal.c:2683 arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x14a/0x2a0 kernel/entry/common.c:218 __do_fast_syscall_32+0x82/0x120 arch/x86/entry/common.c:389 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #0 (rfcomm_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137 lock_acquire kernel/locking/lockdep.c:5754 [inline] lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752 rfcomm_dlc_exists+0x5f/0x1a0 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+0xa73/0x1e30 net/bluetooth/rfcomm/tty.c:587 rfcomm_sock_ioctl net/bluetooth/rfcomm/sock.c:869 [inline] rfcomm_sock_compat_ioctl+0xba/0xe0 net/bluetooth/rfcomm/sock.c:882 compat_sock_ioctl+0x181/0x7f0 net/socket.c:3521 __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1004 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e 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-executor.3/7638: #0: ffff88805c308258 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1673 [inline] #0: ffff88805c308258 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_ioctl net/bluetooth/rfcomm/sock.c:868 [inline] #0: ffff88805c308258 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_compat_ioctl+0xac/0xe0 net/bluetooth/rfcomm/sock.c:882 #1: ffffffff8f57a148 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline] #1: ffffffff8f57a148 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x993/0x1e30 net/bluetooth/rfcomm/tty.c:587 stack backtrace: CPU: 3 PID: 7638 Comm: syz-executor.3 Not tainted 6.9.0-rc6-syzkaller-00046-g18daea77cca6 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2187 check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137 lock_acquire kernel/locking/lockdep.c:5754 [inline] lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752 rfcomm_dlc_exists+0x5f/0x1a0 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+0xa73/0x1e30 net/bluetooth/rfcomm/tty.c:587 rfcomm_sock_ioctl net/bluetooth/rfcomm/sock.c:869 [inline] rfcomm_sock_compat_ioctl+0xba/0xe0 net/bluetooth/rfcomm/sock.c:882 compat_sock_ioctl+0x181/0x7f0 net/socket.c:3521 __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1004 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf7342579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f5f345ac EFLAGS: 00000292 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 000000000000000c RCX: 00000000400452c8 RDX: 0000000020000100 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi