====================================================== WARNING: possible circular locking dependency detected 4.14.94+ #12 Not tainted ------------------------------------------------------ syz-executor4/29926 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: (&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-executor4/29926: #0: (&p->lock){+.+.}, at: [] seq_read+0xcd/0x1180 fs/seq_file.c:165 stack backtrace: CPU: 0 PID: 29926 Comm: syz-executor4 Not tainted 4.14.94+ #12 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=1400 audit(1548013162.548:93): avc: denied { module_load } for pid=30045 comm="syz-executor2" path="/sys/kernel/debug/kcov" dev="debugfs" ino=5005 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:debugfs_t:s0 tclass=system permissive=1 F2FS-fs (loop1): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop1): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop5): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop1): invalid crc value F2FS-fs (loop1): invalid crc value F2FS-fs (loop5): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop1): Failed to get valid F2FS checkpoint F2FS-fs (loop1): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop5): invalid crc value F2FS-fs (loop1): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop5): invalid crc value F2FS-fs (loop1): invalid crc value F2FS-fs (loop5): Failed to get valid F2FS checkpoint F2FS-fs (loop1): invalid crc value F2FS-fs (loop5): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop1): Failed to get valid F2FS checkpoint F2FS-fs (loop5): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop5): invalid crc value F2FS-fs (loop5): invalid crc value F2FS-fs (loop5): Failed to get valid F2FS checkpoint F2FS-fs (loop5): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop5): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop5): invalid crc value ip6_tunnel: ip6tnl2 xmit: Local address not yet configured! F2FS-fs (loop5): invalid crc value F2FS-fs (loop5): Failed to get valid F2FS checkpoint F2FS-fs (loop5): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop5): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop5): invalid crc value F2FS-fs (loop5): invalid crc value F2FS-fs (loop5): Failed to get valid F2FS checkpoint F2FS-fs (loop4): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop4): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop4): invalid crc value F2FS-fs (loop4): invalid crc value F2FS-fs (loop4): Failed to get valid F2FS checkpoint F2FS-fs (loop4): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop4): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop4): invalid crc value F2FS-fs (loop4): invalid crc value F2FS-fs (loop4): Failed to get valid F2FS checkpoint F2FS-fs (loop5): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop5): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop5): invalid crc value F2FS-fs (loop5): invalid crc value F2FS-fs (loop5): Failed to get valid F2FS checkpoint F2FS-fs (loop5): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop5): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop5): invalid crc value F2FS-fs (loop5): invalid crc value F2FS-fs (loop1): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop5): Failed to get valid F2FS checkpoint F2FS-fs (loop1): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop1): invalid crc value F2FS-fs (loop1): invalid crc value F2FS-fs (loop1): Failed to get valid F2FS checkpoint F2FS-fs (loop1): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop1): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop1): invalid crc value F2FS-fs (loop1): invalid crc value F2FS-fs (loop1): Failed to get valid F2FS checkpoint ip6_tunnel: ip6tnl2 xmit: Local address not yet configured! ip6_tunnel: ip6tnl1 xmit: Local address not yet configured! F2FS-fs (loop3): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop3): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop3): invalid crc value F2FS-fs (loop3): invalid crc value F2FS-fs (loop3): Failed to get valid F2FS checkpoint F2FS-fs (loop3): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop3): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop3): invalid crc value F2FS-fs (loop3): invalid crc value F2FS-fs (loop3): Failed to get valid F2FS checkpoint F2FS-fs (loop4): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop4): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop4): invalid crc value F2FS-fs (loop4): invalid crc value F2FS-fs (loop4): Failed to get valid F2FS checkpoint F2FS-fs (loop4): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop4): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop4): invalid crc value F2FS-fs (loop4): invalid crc value F2FS-fs (loop4): Failed to get valid F2FS checkpoint F2FS-fs (loop3): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop3): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop3): invalid crc value F2FS-fs (loop3): invalid crc value F2FS-fs (loop3): Failed to get valid F2FS checkpoint F2FS-fs (loop3): Magic Mismatch, valid(0xf2f52010) - read(0x0) F2FS-fs (loop3): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop3): invalid crc value F2FS-fs (loop3): invalid crc value F2FS-fs (loop3): Failed to get valid F2FS checkpoint