====================================================== WARNING: possible circular locking dependency detected 4.14.167-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.5/26909 is trying to acquire lock: (&sig->cred_guard_mutex){+.+.}, at: [] proc_pid_attr_write+0x163/0x290 fs/proc/base.c:2585 but task is already holding lock: (&pipe->mutex/1){+.+.}, at: [] pipe_lock_nested fs/pipe.c:67 [inline] (&pipe->mutex/1){+.+.}, at: [] pipe_lock+0x63/0x80 fs/pipe.c:75 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&pipe->mutex/1){+.+.}: lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 pipe_lock_nested fs/pipe.c:67 [inline] pipe_lock+0x63/0x80 fs/pipe.c:75 iter_file_splice_write+0x15e/0xad0 fs/splice.c:699 do_splice_from fs/splice.c:851 [inline] do_splice fs/splice.c:1147 [inline] SYSC_splice fs/splice.c:1402 [inline] SyS_splice+0xd92/0x1430 fs/splice.c:1382 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #2 (sb_writers#4){.+.+}: lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x1ae/0x2f0 fs/super.c:1363 sb_start_write include/linux/fs.h:1548 [inline] mnt_want_write+0x3f/0xb0 fs/namespace.c:386 ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:25 ovl_xattr_set+0x4f/0x270 fs/overlayfs/inode.c:214 ovl_posix_acl_xattr_set+0x3f9/0x830 fs/overlayfs/super.c:762 __vfs_setxattr+0xd8/0x130 fs/xattr.c:150 __vfs_setxattr_noperm+0x102/0x3c0 fs/xattr.c:181 vfs_setxattr+0xc5/0xf0 fs/xattr.c:224 setxattr+0x1de/0x350 fs/xattr.c:453 path_setxattr+0x11f/0x140 fs/xattr.c:472 SYSC_lsetxattr fs/xattr.c:494 [inline] SyS_lsetxattr+0x38/0x50 fs/xattr.c:490 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #1 (&ovl_i_mutex_dir_key[depth]){++++}: lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 down_read+0x3b/0xb0 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:728 [inline] do_last fs/namei.c:3330 [inline] path_openat+0x191c/0x3f70 fs/namei.c:3566 do_filp_open+0x18e/0x250 fs/namei.c:3600 do_open_execat+0xe7/0x4a0 fs/exec.c:849 do_execveat_common.isra.0+0x6d5/0x1dd0 fs/exec.c:1740 do_execve fs/exec.c:1847 [inline] SYSC_execve fs/exec.c:1928 [inline] SyS_execve+0x39/0x50 fs/exec.c:1923 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (&sig->cred_guard_mutex){+.+.}: 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+0x2cb3/0x4620 kernel/locking/lockdep.c:3487 lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 mutex_lock_interruptible_nested+0x16/0x20 kernel/locking/mutex.c:930 proc_pid_attr_write+0x163/0x290 fs/proc/base.c:2585 __vfs_write+0x105/0x6b0 fs/read_write.c:480 __kernel_write+0xfc/0x370 fs/read_write.c:501 write_pipe_buf+0x148/0x1c0 fs/splice.c:797 splice_from_pipe_feed fs/splice.c:502 [inline] __splice_from_pipe+0x348/0x780 fs/splice.c:626 splice_from_pipe+0xf0/0x150 fs/splice.c:661 default_file_splice_write+0x3c/0x80 fs/splice.c:809 do_splice_from fs/splice.c:851 [inline] do_splice fs/splice.c:1147 [inline] SYSC_splice fs/splice.c:1402 [inline] SyS_splice+0xd92/0x1430 fs/splice.c:1382 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Chain exists of: &sig->cred_guard_mutex --> sb_writers#4 --> &pipe->mutex/1 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&pipe->mutex/1); lock(sb_writers#4); lock(&pipe->mutex/1); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 2 locks held by syz-executor.5/26909: #0: (sb_writers#7){.+.+}, at: [] file_start_write include/linux/fs.h:2707 [inline] #0: (sb_writers#7){.+.+}, at: [] do_splice fs/splice.c:1146 [inline] #0: (sb_writers#7){.+.+}, at: [] SYSC_splice fs/splice.c:1402 [inline] #0: (sb_writers#7){.+.+}, at: [] SyS_splice+0xf3a/0x1430 fs/splice.c:1382 #1: (&pipe->mutex/1){+.+.}, at: [] pipe_lock_nested fs/pipe.c:67 [inline] #1: (&pipe->mutex/1){+.+.}, at: [] pipe_lock+0x63/0x80 fs/pipe.c:75 stack backtrace: CPU: 0 PID: 26909 Comm: syz-executor.5 Not tainted 4.14.167-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x142/0x197 lib/dump_stack.c:58 print_circular_bug.isra.0.cold+0x1cc/0x28f 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+0x2cb3/0x4620 kernel/locking/lockdep.c:3487 lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 mutex_lock_interruptible_nested+0x16/0x20 kernel/locking/mutex.c:930 proc_pid_attr_write+0x163/0x290 fs/proc/base.c:2585 __vfs_write+0x105/0x6b0 fs/read_write.c:480 __kernel_write+0xfc/0x370 fs/read_write.c:501 write_pipe_buf+0x148/0x1c0 fs/splice.c:797 splice_from_pipe_feed fs/splice.c:502 [inline] __splice_from_pipe+0x348/0x780 fs/splice.c:626 splice_from_pipe+0xf0/0x150 fs/splice.c:661 default_file_splice_write+0x3c/0x80 fs/splice.c:809 do_splice_from fs/splice.c:851 [inline] do_splice fs/splice.c:1147 [inline] SYSC_splice fs/splice.c:1402 [inline] SyS_splice+0xd92/0x1430 fs/splice.c:1382 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45b349 RSP: 002b:00007f8194ae4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 00007f8194ae56d4 RCX: 000000000045b349 RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000080000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000b3e R14: 00000000004ccc7e R15: 000000000075bf2c selinux_nlmsg_perm: 235 callbacks suppressed SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27006 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27006 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27006 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27006 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27006 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27006 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27006 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27006 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27006 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27006 comm=syz-executor.5 x_tables: ip_tables: rpfilter match: used from hooks INPUT, but only valid from PREROUTING x_tables: ip_tables: rpfilter match: used from hooks INPUT, but only valid from PREROUTING audit: type=1804 audit(1579880755.027:283): pid=27197 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op="invalid_pcr" cause="ToMToU" comm="syz-executor.3" name="/root/syzkaller-testdir926441775/syzkaller.5vQr5P/2226/file0" dev="sda1" ino=16617 res=1 audit: type=1400 audit(1579880756.757:284): avc: denied { getattr } for pid=27285 comm="syz-executor.2" path="socket:[383848]" dev="sockfs" ino=383848 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 selinux_nlmsg_perm: 352 callbacks suppressed SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27350 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27350 comm=syz-executor.5 caif:caif_disconnect_client(): nothing to disconnect SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27350 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27350 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27350 comm=syz-executor.5 caif:caif_disconnect_client(): nothing to disconnect SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27350 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27350 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27350 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27350 comm=syz-executor.5 SELinux: unrecognized netlink message: protocol=4 nlmsg_type=0 sclass=netlink_tcpdiag_socket pig=27350 comm=syz-executor.5 overlayfs: unrecognized mount option "metacopy=off" or missing value audit: type=1804 audit(1579880759.737:285): pid=27513 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op="invalid_pcr" cause="open_writers" comm="syz-executor.1" name="file0" dev="sda1" ino=16909 res=1 audit: type=1804 audit(1579880759.797:286): pid=27522 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op="invalid_pcr" cause="open_writers" comm="syz-executor.1" name="file0" dev="sda1" ino=16909 res=1