====================================================== WARNING: possible circular locking dependency detected 4.14.91+ #3 Not tainted ------------------------------------------------------ syz-executor2/10563 is trying to acquire lock: (&sig->cred_guard_mutex){+.+.}, at: [] lock_trace+0x3f/0xc0 fs/proc/base.c:408 but task is already holding lock: audit: type=1400 audit(2000000253.771:120): avc: denied { map } for pid=10593 comm="syz-executor4" path="/dev/null" dev="devtmpfs" ino=1028 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:null_device_t:s0 tclass=chr_file permissive=1 (&p->lock){+.+.}, at: [] seq_read+0xcd/0x1180 fs/seq_file.c:165 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&p->lock){+.+.}: -> #1 (&pipe->mutex/1){+.+.}: -> #0 (&sig->cred_guard_mutex){+.+.}: other info that might help us debug this: Chain exists of: &sig->cred_guard_mutex --> &pipe->mutex/1 --> &p->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); lock(&pipe->mutex/1); lock(&p->lock); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 1 lock held by syz-executor2/10563: FAT-fs (loop3): bogus number of reserved sectors #0: (&p->lock){+.+.}, at: [] seq_read+0xcd/0x1180 fs/seq_file.c:165 stack backtrace: CPU: 0 PID: 10563 Comm: syz-executor2 Not tainted 4.14.91+ #3 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 FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem keychord: Insufficient bytes present for keycount 16 FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem keychord: Insufficient bytes present for keycount 16 FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem binder: 12022:12025 got transaction to invalid handle binder: 12022:12025 transaction failed 29201/-22, size 48-8 line 3012 binder: 12022:12042 got transaction to invalid handle binder: 12022:12042 transaction failed 29201/-22, size 48-8 line 3012 binder: undelivered TRANSACTION_ERROR: 29201 binder: undelivered TRANSACTION_ERROR: 29201 FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem binder: 12179:12183 got transaction to invalid handle binder: 12179:12183 transaction failed 29201/-22, size 48-8 line 3012 FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem binder: undelivered TRANSACTION_ERROR: 29201 binder: 12230:12238 got transaction to invalid handle FAT-fs (loop3): bogus number of reserved sectors FAT-fs (loop3): Can't find a valid FAT filesystem binder: 12230:12238 transaction failed 29201/-22, size 48-8 line 3012