audit: type=1326 audit(1552729326.435:43): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=5356 comm="syz-executor.5" exe="/root/syz-executor.5" sig=0 arch=c000003e syscall=202 compat=0 ip=0x458079 code=0x50000 ====================================================== WARNING: possible circular locking dependency detected 4.14.106+ #30 Not tainted ------------------------------------------------------ syz-executor.2/5394 is trying to acquire lock: (&pipe->mutex/1){+.+.}, at: [] __pipe_lock fs/pipe.c:88 [inline] (&pipe->mutex/1){+.+.}, at: [] fifo_open+0x156/0x9b0 fs/pipe.c:921 but task is already holding lock: (&sig->cred_guard_mutex){+.+.}, at: [] prepare_bprm_creds+0x51/0x110 fs/exec.c:1389 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&sig->cred_guard_mutex){+.+.}: -> #0 (&pipe->mutex/1){+.+.}: other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sig->cred_guard_mutex); lock(&pipe->mutex/1); lock(&sig->cred_guard_mutex); lock(&pipe->mutex/1); *** DEADLOCK *** 1 lock held by syz-executor.2/5394: #0: (&sig->cred_guard_mutex){+.+.}, at: [] prepare_bprm_creds+0x51/0x110 fs/exec.c:1389 stack backtrace: CPU: 0 PID: 5394 Comm: syz-executor.2 Not tainted 4.14.106+ #30 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xb9/0x10e lib/dump_stack.c:53 print_circular_bug.isra.0.cold+0x2dc/0x425 kernel/locking/lockdep.c:1258 audit: type=1326 audit(1552729326.435:44): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=5356 comm="syz-executor.5" exe="/root/syz-executor.5" sig=0 arch=c000003e syscall=202 compat=0 ip=0x458079 code=0x50000 audit: type=1326 audit(1552729326.435:45): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=5356 comm="syz-executor.5" exe="/root/syz-executor.5" sig=0 arch=c000003e syscall=202 compat=0 ip=0x458079 code=0x50000 binder: 5397:5405 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 audit: type=1326 audit(1552729326.435:46): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=5356 comm="syz-executor.5" exe="/root/syz-executor.5" sig=0 arch=c000003e syscall=202 compat=0 ip=0x458079 code=0x50000 audit: type=1326 audit(1552729326.435:47): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=5356 comm="syz-executor.5" exe="/root/syz-executor.5" sig=0 arch=c000003e syscall=202 compat=0 ip=0x458079 code=0x50000 binder: 5397:5459 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189 binder: undelivered TRANSACTION_ERROR: 29189 binder: 5468:5474 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: 5486:5504 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189 binder: 5512:5522 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: 5518:5523 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189 binder: 5532:5542 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189 binder: undelivered TRANSACTION_ERROR: 29189 binder: 5555:5557 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: 5562:5567 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189 binder: 5573:5591 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 ip6_tunnel: ip6tnl1 xmit: Local address not yet configured! binder: undelivered TRANSACTION_ERROR: 29189 binder: 5596:5599 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189 binder: 5603:5608 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189 binder: undelivered TRANSACTION_ERROR: 29189 binder: undelivered TRANSACTION_ERROR: 29189 binder: 5648:5664 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: 5649:5665 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189 binder: undelivered TRANSACTION_ERROR: 29189 binder: 5696:5711 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: 5702:5713 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189 binder: undelivered TRANSACTION_ERROR: 29189 binder: 5746:5765 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: 5743:5766 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189 binder: undelivered TRANSACTION_ERROR: 29189 binder: 5785:5802 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: 5784:5804 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189 binder: undelivered TRANSACTION_ERROR: 29189 binder: 5825:5828 transaction failed 29189/-22, size 3210520082187264776--4941763985495295841 line 3018 binder: undelivered TRANSACTION_ERROR: 29189