** unsafe for production use. ** ** ** ** If you see this message and you are not debugging ** ====================================================== WARNING: possible circular locking dependency detected ** the kernel, report this immediately to your vendor! ** 4.14.91+ #3 Not tainted ------------------------------------------------------ syz-executor4/8816 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 ( ** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE ** &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-executor4/8816: #0: (&p->lock){+.+.}, at: [] seq_read+0xcd/0x1180 fs/seq_file.c:165 stack backtrace: CPU: 1 PID: 8816 Comm: syz-executor4 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 netlink: 12 bytes leftover after parsing attributes in process `syz-executor5'. audit: type=1400 audit(1546768023.599:109): avc: denied { create } for pid=8941 comm="syz-executor3" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_connector_socket permissive=1 audit: type=1400 audit(1546768026.499:110): avc: denied { map } for pid=8956 comm="syz-executor3" path="socket:[24221]" dev="sockfs" ino=24221 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=tcp_socket permissive=1 audit: type=1400 audit(1546768026.539:111): avc: denied { setattr } for pid=8959 comm="syz-executor1" name="NETLINK" dev="sockfs" ino=24229 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1 binder: 9049:9051 unknown command 1073769483 binder: 9049:9051 ioctl c0306201 20000400 returned -22 binder: 9049:9055 unknown command 1073769483 binder: 9049:9055 ioctl c0306201 20000400 returned -22