====================================================== WARNING: possible circular locking dependency detected 4.14.76+ #20 Not tainted ------------------------------------------------------ syz-executor1/8706 is trying to acquire lock: (&sig->cred_guard_mutex){+.+.}, at: [] do_io_accounting+0x1d7/0x770 fs/proc/base.c:2731 but task is already holding lock: (&p->lock){+.+.}, at: [] seq_read+0xd4/0x11d0 fs/seq_file.c:165 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf5/0x1480 kernel/locking/mutex.c:893 seq_read+0xd4/0x11d0 fs/seq_file.c:165 proc_reg_read+0xef/0x170 fs/proc/inode.c:217 do_loop_readv_writev fs/read_write.c:698 [inline] do_iter_read+0x3cc/0x580 fs/read_write.c:922 vfs_readv+0xe6/0x150 fs/read_write.c:984 kernel_readv fs/splice.c:361 [inline] default_file_splice_read+0x495/0x860 fs/splice.c:416 do_splice_to+0x102/0x150 fs/splice.c:880 do_splice fs/splice.c:1173 [inline] SYSC_splice fs/splice.c:1402 [inline] SyS_splice+0xf4d/0x12a0 fs/splice.c:1382 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #1 (&pipe->mutex/1){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf5/0x1480 kernel/locking/mutex.c:893 __pipe_lock fs/pipe.c:88 [inline] fifo_open+0x156/0x9d0 fs/pipe.c:921 do_dentry_open+0x426/0xda0 fs/open.c:764 vfs_open+0x11c/0x210 fs/open.c:878 do_last fs/namei.c:3408 [inline] path_openat+0x4eb/0x23a0 fs/namei.c:3550 do_filp_open+0x197/0x270 fs/namei.c:3584 do_open_execat+0x10d/0x5b0 fs/exec.c:849 do_execveat_common.isra.14+0x6cb/0x1d60 fs/exec.c:1740 do_execve fs/exec.c:1847 [inline] SYSC_execve fs/exec.c:1928 [inline] SyS_execve+0x34/0x40 fs/exec.c:1923 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (&sig->cred_guard_mutex){+.+.}: lock_acquire+0x10f/0x380 kernel/locking/lockdep.c:3991 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf5/0x1480 kernel/locking/mutex.c:893 do_io_accounting+0x1d7/0x770 fs/proc/base.c:2731 proc_single_show+0xf1/0x160 fs/proc/base.c:762 traverse+0x32b/0x8a0 fs/seq_file.c:111 seq_read+0xc94/0x11d0 fs/seq_file.c:192 do_loop_readv_writev fs/read_write.c:698 [inline] do_iter_read+0x3cc/0x580 fs/read_write.c:922 vfs_readv+0xe6/0x150 fs/read_write.c:984 do_preadv+0x187/0x230 fs/read_write.c:1068 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 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-executor1/8706: #0: (&p->lock){+.+.}, at: [] seq_read+0xd4/0x11d0 fs/seq_file.c:165 stack backtrace: CPU: 0 PID: 8706 Comm: syz-executor1 Not tainted 4.14.76+ #20 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xb9/0x11b lib/dump_stack.c:53 print_circular_bug.isra.18.cold.43+0x2d3/0x40c kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1901 [inline] check_prevs_add kernel/locking/lockdep.c:2018 [inline] validate_chain kernel/locking/lockdep.c:2460 [inline] __lock_acquire+0x2ff9/0x4320 kernel/locking/lockdep.c:3487 lock_acquire+0x10f/0x380 kernel/locking/lockdep.c:3991 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf5/0x1480 kernel/locking/mutex.c:893 do_io_accounting+0x1d7/0x770 fs/proc/base.c:2731 proc_single_show+0xf1/0x160 fs/proc/base.c:762 traverse+0x32b/0x8a0 fs/seq_file.c:111 seq_read+0xc94/0x11d0 fs/seq_file.c:192 do_loop_readv_writev fs/read_write.c:698 [inline] do_iter_read+0x3cc/0x580 fs/read_write.c:922 vfs_readv+0xe6/0x150 fs/read_write.c:984 do_preadv+0x187/0x230 fs/read_write.c:1068 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x457569 RSP: 002b:00007fd96af9cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000457569 RDX: 00000000000001d0 RSI: 00000000200017c0 RDI: 0000000000000004 RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 000000001f000000 R11: 0000000000000246 R12: 00007fd96af9d6d4 R13: 00000000004c3088 R14: 00000000004d4a40 R15: 00000000ffffffff tmpfs: Bad mount option pݏԭd?]-7&LalXXi;A%{ tmpfs: Bad mount option pݏԭd?]-7&LalXXi;A%{ binder: 8844:8846 ioctl 40106614 20000380 returned -22 binder: 8844:8846 ioctl 8904 20000280 returned -22 binder: 8844:8850 ioctl 40106614 20000380 returned -22 binder: 8844:8851 ioctl 8904 20000280 returned -22 binder: 8870:8878 ioctl 40106614 20000380 returned -22 binder: 8870:8878 ioctl 8904 20000280 returned -22 binder: 8897:8904 ioctl 40106614 20000380 returned -22 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=258 sclass=netlink_audit_socket pig=8898 comm=syz-executor2 binder: 8897:8904 ioctl 8904 20000280 returned -22 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=59584 sclass=netlink_audit_socket pig=8898 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=680 sclass=netlink_audit_socket pig=8898 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=9092 sclass=netlink_audit_socket pig=8898 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=1417 sclass=netlink_audit_socket pig=8898 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=10306 sclass=netlink_audit_socket pig=8898 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=0 sclass=netlink_audit_socket pig=8898 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=9364 sclass=netlink_audit_socket pig=8898 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=9284 sclass=netlink_audit_socket pig=8898 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=9 nlmsg_type=0 sclass=netlink_audit_socket pig=8898 comm=syz-executor2 audit: type=1400 audit(1539874885.902:53): avc: denied { relabelto } for pid=9746 comm="syz-executor3" name="UNIX" dev="sockfs" ino=24348 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:passwd_exec_t:s0 tclass=unix_stream_socket permissive=1 netlink: 12 bytes leftover after parsing attributes in process `syz-executor1'. netlink: 12 bytes leftover after parsing attributes in process `syz-executor1'. netlink: 20 bytes leftover after parsing attributes in process `syz-executor1'. netlink: 20 bytes leftover after parsing attributes in process `syz-executor1'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor1'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor1'. selinux_nlmsg_perm: 352 callbacks suppressed SELinux: unrecognized netlink message: protocol=0 nlmsg_type=55056 sclass=netlink_route_socket pig=10002 comm=syz-executor1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=55056 sclass=netlink_route_socket pig=10019 comm=syz-executor1 netlink: 12 bytes leftover after parsing attributes in process `syz-executor1'. netlink: 12 bytes leftover after parsing attributes in process `syz-executor1'. SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=10153 comm=syz-executor2 netlink: 12 bytes leftover after parsing attributes in process `syz-executor1'. audit: type=1400 audit(1539874887.582:54): avc: denied { module_load } for pid=10151 comm="syz-executor3" path="/selinux/avc/cache_threshold" dev="selinuxfs" ino=25 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:security_t:s0 tclass=system permissive=1 netlink: 12 bytes leftover after parsing attributes in process `syz-executor1'. SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=10171 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=59664 sclass=netlink_route_socket pig=10212 comm=syz-executor1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=8 sclass=netlink_route_socket pig=10329 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=8 sclass=netlink_route_socket pig=10345 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=8 sclass=netlink_route_socket pig=10386 comm=syz-executor2 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=8 sclass=netlink_route_socket pig=10400 comm=syz-executor2