====================================================== WARNING: possible circular locking dependency detected kobject: 'loop4' (00000000071c99d5): kobject_uevent_env 5.0.0+ #10 Not tainted ------------------------------------------------------ kobject: 'loop4' (00000000071c99d5): fill_kobj_path: path = '/devices/virtual/block/loop4' syz-executor.5/11524 is trying to acquire lock: 00000000f232ccee (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] 00000000f232ccee (&pipe->mutex/1){+.+.}, at: fifo_open+0x159/0xb00 fs/pipe.c:904 but task is already holding lock: 00000000fa2a7a89 (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds fs/exec.c:1407 [inline] 00000000fa2a7a89 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 fs/exec.c:1750 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&sig->cred_guard_mutex){+.+.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 lock_trace+0x4a/0xe0 fs/proc/base.c:384 proc_pid_stack+0x13e/0x2c0 fs/proc/base.c:434 proc_single_show+0xf6/0x170 fs/proc/base.c:739 seq_read+0x4db/0x1130 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:700 [inline] do_loop_readv_writev fs/read_write.c:687 [inline] do_iter_read+0x4a9/0x660 fs/read_write.c:921 vfs_readv+0xf0/0x160 fs/read_write.c:983 do_preadv+0x1c4/0x280 fs/read_write.c:1067 __do_sys_preadv fs/read_write.c:1117 [inline] __se_sys_preadv fs/read_write.c:1112 [inline] __x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1112 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&p->lock){+.+.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 seq_read+0x71/0x1130 fs/seq_file.c:161 proc_reg_read+0x1fe/0x2c0 fs/proc/inode.c:229 do_loop_readv_writev fs/read_write.c:700 [inline] do_loop_readv_writev fs/read_write.c:687 [inline] do_iter_read+0x4a9/0x660 fs/read_write.c:921 vfs_readv+0xf0/0x160 fs/read_write.c:983 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x475/0x890 fs/splice.c:417 do_splice_to+0x12a/0x190 fs/splice.c:880 do_splice+0x10a0/0x1490 fs/splice.c:1187 __do_sys_splice fs/splice.c:1428 [inline] __se_sys_splice fs/splice.c:1408 [inline] __x64_sys_splice+0x2c6/0x330 fs/splice.c:1408 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&pipe->mutex/1){+.+.}: check_prevs_add kernel/locking/lockdep.c:2324 [inline] validate_chain kernel/locking/lockdep.c:2705 [inline] __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3692 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 __pipe_lock fs/pipe.c:83 [inline] fifo_open+0x159/0xb00 fs/pipe.c:904 do_dentry_open+0x488/0x1160 fs/open.c:771 vfs_open+0xa0/0xd0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x10e9/0x46e0 fs/namei.c:3534 do_filp_open+0x1a1/0x280 fs/namei.c:3564 do_open_execat+0x137/0x690 fs/exec.c:856 __do_execve_file.isra.0+0x178d/0x23f0 fs/exec.c:1758 do_execveat_common fs/exec.c:1865 [inline] do_execve fs/exec.c:1882 [inline] __do_sys_execve fs/exec.c:1963 [inline] __se_sys_execve fs/exec.c:1958 [inline] __x64_sys_execve+0x8f/0xc0 fs/exec.c:1958 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &pipe->mutex/1 --> &p->lock --> &sig->cred_guard_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sig->cred_guard_mutex); lock(&p->lock); lock(&sig->cred_guard_mutex); lock(&pipe->mutex/1); *** DEADLOCK *** 1 lock held by syz-executor.5/11524: #0: 00000000fa2a7a89 (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds fs/exec.c:1407 [inline] #0: 00000000fa2a7a89 (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 fs/exec.c:1750 stack backtrace: CPU: 1 PID: 11524 Comm: syz-executor.5 Not tainted 5.0.0+ #10 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1562 check_prev_add.constprop.0+0xf11/0x23c0 kernel/locking/lockdep.c:2211 check_prevs_add kernel/locking/lockdep.c:2324 [inline] validate_chain kernel/locking/lockdep.c:2705 [inline] __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3692 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 __pipe_lock fs/pipe.c:83 [inline] fifo_open+0x159/0xb00 fs/pipe.c:904 do_dentry_open+0x488/0x1160 fs/open.c:771 vfs_open+0xa0/0xd0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x10e9/0x46e0 fs/namei.c:3534 do_filp_open+0x1a1/0x280 fs/namei.c:3564 do_open_execat+0x137/0x690 fs/exec.c:856 __do_execve_file.isra.0+0x178d/0x23f0 fs/exec.c:1758 do_execveat_common fs/exec.c:1865 [inline] do_execve fs/exec.c:1882 [inline] __do_sys_execve fs/exec.c:1963 [inline] __se_sys_execve fs/exec.c:1958 [inline] __x64_sys_execve+0x8f/0xc0 fs/exec.c:1958 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457f29 Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fdb11978c78 EFLAGS: 00000246 ORIG_RAX: 000000000000003b RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457f29 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000400 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdb119796d3 R13: 00000000004be513 R14: 00000000004cee00 R15: 00000000ffffffff protocol 88fb is buggy, dev hsr_slave_0 protocol 88fb is buggy, dev hsr_slave_1 kobject: 'rfkill173' (000000006fb48884): kobject_uevent_env kobject: 'rfkill172' (00000000fccd754d): kobject_uevent_env kobject: 'rfkill173' (000000006fb48884): fill_kobj_path: path = '/devices/virtual/bluetooth/hci4/rfkill173' kobject: 'rfkill172' (00000000fccd754d): fill_kobj_path: path = '/devices/virtual/bluetooth/hci1/rfkill172' kobject: 'rfkill173' (000000006fb48884): kobject_cleanup, parent (null) kobject: 'rfkill172' (00000000fccd754d): kobject_cleanup, parent (null) kobject: 'rfkill172' (00000000fccd754d): calling ktype release kobject: 'loop0' (0000000006d15c94): kobject_uevent_env kobject: 'rfkill172': free name kobject: 'rfkill173' (000000006fb48884): calling ktype release kobject: 'loop0' (0000000006d15c94): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'rfkill173': free name kobject: 'hci1' (000000002c762e03): kobject_uevent_env kobject: 'hci1' (000000002c762e03): fill_kobj_path: path = '/devices/virtual/bluetooth/hci1' kobject: 'hci4' (000000007871f18b): kobject_uevent_env kobject: 'loop4' (00000000071c99d5): kobject_uevent_env kobject: 'loop4' (00000000071c99d5): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'hci4' (000000007871f18b): fill_kobj_path: path = '/devices/virtual/bluetooth/hci4' kobject: 'hci1' (000000002c762e03): kobject_cleanup, parent (null) kobject: 'hci4' (000000007871f18b): kobject_cleanup, parent (null) kobject: 'hci1' (000000002c762e03): calling ktype release kobject: 'hci4' (000000007871f18b): calling ktype release kobject: 'hci1': free name kobject: 'hci4': free name kobject: 'loop0' (0000000006d15c94): kobject_uevent_env kobject: 'loop0' (0000000006d15c94): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop3' (000000007a25bd5a): kobject_uevent_env kobject: 'loop3' (000000007a25bd5a): fill_kobj_path: path = '/devices/virtual/block/loop3' kobject: 'rfkill174' (0000000094a21f50): kobject_uevent_env kobject: 'loop5' (00000000d7b4f410): kobject_uevent_env kobject: 'rfkill174' (0000000094a21f50): fill_kobj_path: path = '/devices/virtual/bluetooth/hci5/rfkill174' kobject: 'loop5' (00000000d7b4f410): fill_kobj_path: path = '/devices/virtual/block/loop5' kobject: 'rfkill174' (0000000094a21f50): kobject_cleanup, parent (null) kobject: 'rfkill174' (0000000094a21f50): calling ktype release kobject: 'loop0' (0000000006d15c94): kobject_uevent_env kobject: 'rfkill174': free name kobject: 'loop0' (0000000006d15c94): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'hci5' (0000000008d48b61): kobject_uevent_env kobject: 'hci5' (0000000008d48b61): fill_kobj_path: path = '/devices/virtual/bluetooth/hci5' kobject: 'hci5' (0000000008d48b61): kobject_cleanup, parent (null) kobject: 'hci5' (0000000008d48b61): calling ktype release kobject: 'loop4' (00000000071c99d5): kobject_uevent_env kobject: 'hci5': free name kobject: 'loop4' (00000000071c99d5): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'hci1' (000000001d26fa09): kobject_add_internal: parent: 'bluetooth', set: 'devices' kobject: 'loop2' (00000000cc20b441): kobject_uevent_env kobject: 'hci1' (000000001d26fa09): kobject_uevent_env kobject: 'hci1' (000000001d26fa09): fill_kobj_path: path = '/devices/virtual/bluetooth/hci1' kobject: 'loop2' (00000000cc20b441): fill_kobj_path: path = '/devices/virtual/block/loop2' kobject: 'rfkill176' (00000000ac31e9be): kobject_add_internal: parent: 'hci1', set: 'devices' kobject: 'rfkill176' (00000000ac31e9be): kobject_uevent_env kobject: 'loop0' (0000000006d15c94): kobject_uevent_env kobject: 'loop0' (0000000006d15c94): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'rfkill176' (00000000ac31e9be): fill_kobj_path: path = '/devices/virtual/bluetooth/hci1/rfkill176' kobject: 'loop0' (0000000006d15c94): kobject_uevent_env kobject: 'loop0' (0000000006d15c94): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop4' (00000000071c99d5): kobject_uevent_env kobject: 'loop4' (00000000071c99d5): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop5' (00000000d7b4f410): kobject_uevent_env kobject: 'loop5' (00000000d7b4f410): fill_kobj_path: path = '/devices/virtual/block/loop5' Bluetooth: hci0: command 0x1003 tx timeout Bluetooth: hci0: sending frame failed (-49) Bluetooth: hci1: command 0x1003 tx timeout Bluetooth: hci1: sending frame failed (-49) Bluetooth: hci0: command 0x1001 tx timeout Bluetooth: hci0: sending frame failed (-49) Bluetooth: hci1: command 0x1001 tx timeout Bluetooth: hci1: sending frame failed (-49) Bluetooth: hci0: command 0x1009 tx timeout Bluetooth: hci1: command 0x1009 tx timeout