====================================================== WARNING: possible circular locking dependency detected 4.14.94+ #13 Not tainted ------------------------------------------------------ syz-executor1/16398 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: -> #2 (&sig->cred_guard_mutex){+.+.}: -> #1 (&p->lock){+.+.}: -> #0 (&pipe->mutex/1){+.+.}: 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-executor1/16398: #0: (&sig->cred_guard_mutex){+.+.}, at: [] prepare_bprm_creds+0x51/0x110 fs/exec.c:1389 stack backtrace: CPU: 1 PID: 16398 Comm: syz-executor1 Not tainted 4.14.94+ #13 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 ip6_tunnel: ip6tnl1 xmit: Local address not yet configured! binder_alloc: 3238: binder_alloc_buf, no vma EXT4-fs (loop4): VFS: Can't find ext4 filesystem binder: 16475:16479 transaction failed 29189/-3, size 0-0 line 3135 binder: undelivered TRANSACTION_ERROR: 29189 ip6_tunnel: ip6tnl2 xmit: Local address not yet configured! binder_alloc: 3238: binder_alloc_buf, no vma binder: 16496:16499 transaction failed 29189/-3, size 0-0 line 3135 binder: undelivered TRANSACTION_ERROR: 29189 binder_alloc: 3238: binder_alloc_buf, no vma binder: 16539:16550 transaction failed 29189/-3, size 0-0 line 3135 binder: undelivered TRANSACTION_ERROR: 29189 binder_alloc: 3238: binder_alloc_buf, no vma binder: 16566:16570 transaction failed 29189/-3, size 0-0 line 3135 binder: undelivered TRANSACTION_ERROR: 29189 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1541 sclass=netlink_route_socket pig=16610 comm=syz-executor3 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1541 sclass=netlink_route_socket pig=16632 comm=syz-executor3 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=1541 sclass=netlink_route_socket pig=16649 comm=syz-executor3 binder: 16709:16711 ioctl c0306201 0 returned -14 binder: 16732:16736 ioctl c0306201 0 returned -14 binder: 16760:16762 ioctl c0306201 0 returned -14 binder_alloc: 3238: binder_alloc_buf, no vma binder: 16883:16886 transaction failed 29189/-3, size 0-0 line 3135 binder: undelivered TRANSACTION_ERROR: 29189 binder: 16898:16905 unknown command 17 binder: 16898:16905 ioctl c0306201 20000040 returned -22 binder: 16918:16920 unknown command 17 binder: 16918:16920 ioctl c0306201 20000040 returned -22 binder: 16932:16937 unknown command 17 binder: 16932:16937 ioctl c0306201 20000040 returned -22 binder_alloc: 3238: binder_alloc_buf, no vma binder: 16973:16977 transaction failed 29189/-3, size 0-0 line 3135 binder: undelivered TRANSACTION_ERROR: 29189 binder: 16993:16997 unknown command 17 binder: 16993:16997 ioctl c0306201 20000040 returned -22 binder: 17008:17011 unknown command 17 binder: 17008:17011 ioctl c0306201 20000040 returned -22 binder: 17031:17034 unknown command 17 binder: 17031:17034 ioctl c0306201 20000040 returned -22 binder_alloc: 3238: binder_alloc_buf, no vma binder: 17042:17051 transaction failed 29189/-3, size 0-0 line 3135 binder: undelivered TRANSACTION_ERROR: 29189 binder: 17074:17080 unknown command 17 binder: 17074:17080 ioctl c0306201 20000040 returned -22 binder: 17093:17094 unknown command 17 binder: 17093:17094 ioctl c0306201 20000040 returned -22 binder: 17105:17113 unknown command 17 binder: 17105:17113 ioctl c0306201 20000040 returned -22 binder: 17128:17131 unknown command 4743953 binder: 17128:17131 ioctl c0306201 20000040 returned -22 binder: 17148:17150 unknown command 4743953 binder: 17148:17150 ioctl c0306201 20000040 returned -22 binder: 17163:17166 unknown command 4743953 binder: 17163:17166 ioctl c0306201 20000040 returned -22 ip6_tunnel: ip6tnl2 xmit: Local address not yet configured! ip6_tunnel: ip6tnl1 xmit: Local address not yet configured! audit: type=1326 audit(1548231967.717:20859): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=17822 comm="syz-executor2" exe="/root/syz-executor2" sig=9 arch=c000003e syscall=228 compat=0 ip=0x45aefa code=0x0 ip6_tunnel: ip6tnl2 xmit: Local address not yet configured! audit: type=1326 audit(1548231968.497:20860): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=17822 comm="syz-executor2" exe="/root/syz-executor2" sig=9 arch=c000003e syscall=228 compat=0 ip=0x45aefa code=0x0