====================================================== [ INFO: possible circular locking dependency detected ] 4.4.174+ #17 Not tainted ------------------------------------------------------- syz-executor.5/16314 is trying to acquire lock: (&pipe->mutex/1){+.+.+.}, at: [] pipe_lock_nested fs/pipe.c:65 [inline] (&pipe->mutex/1){+.+.+.}, at: [] pipe_lock+0x63/0x80 fs/pipe.c:73 but task is already holding lock: (sb_writers#4){.+.+.+}, at: [] file_start_write include/linux/fs.h:2543 [inline] (sb_writers#4){.+.+.+}, at: [] do_splice fs/splice.c:1403 [inline] (sb_writers#4){.+.+.+}, at: [] SYSC_splice fs/splice.c:1707 [inline] (sb_writers#4){.+.+.+}, at: [] SyS_splice+0xf2d/0x13a0 fs/splice.c:1690 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] percpu_down_read include/linux/percpu-rwsem.h:26 [inline] [] __sb_start_write+0x1af/0x310 fs/super.c:1239 [] sb_start_write include/linux/fs.h:1517 [inline] [] ext4_run_li_request fs/ext4/super.c:2685 [inline] [] ext4_lazyinit_thread fs/ext4/super.c:2784 [inline] [] ext4_lazyinit_thread+0x1e4/0x7b0 fs/ext4/super.c:2760 [] kthread+0x273/0x310 kernel/kthread.c:211 [] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:537 [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621 [] ext4_register_li_request+0x2fd/0x7d0 fs/ext4/super.c:2972 [] ext4_remount+0x1366/0x1b90 fs/ext4/super.c:4922 [] do_remount_sb2+0x41b/0x7a0 fs/super.c:781 [] do_remount fs/namespace.c:2347 [inline] [] do_mount+0xfdb/0x2a40 fs/namespace.c:2860 [] SYSC_mount fs/namespace.c:3063 [inline] [] SyS_mount+0x130/0x1d0 fs/namespace.c:3041 [] entry_SYSCALL_64_fastpath+0x1e/0x9a [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621 [] ext4_register_li_request+0x89/0x7d0 fs/ext4/super.c:2945 [] ext4_remount+0x1366/0x1b90 fs/ext4/super.c:4922 [] do_remount_sb2+0x41b/0x7a0 fs/super.c:781 [] do_remount fs/namespace.c:2347 [inline] [] do_mount+0xfdb/0x2a40 fs/namespace.c:2860 [] SYSC_mount fs/namespace.c:3063 [inline] [] SyS_mount+0x130/0x1d0 fs/namespace.c:3041 [] entry_SYSCALL_64_fastpath+0x1e/0x9a [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] down_read+0x42/0x60 kernel/locking/rwsem.c:22 [] iterate_supers+0xe1/0x250 fs/super.c:547 [] selinux_complete_init+0x2f/0x31 security/selinux/hooks.c:6154 [] security_load_policy+0x69d/0x9c0 security/selinux/ss/services.c:2060 [] sel_write_load+0x175/0xf90 security/selinux/selinuxfs.c:535 [] __vfs_write+0x116/0x3d0 fs/read_write.c:491 [] vfs_write+0x182/0x4e0 fs/read_write.c:540 [] SYSC_write fs/read_write.c:587 [inline] [] SyS_write+0xdc/0x1c0 fs/read_write.c:579 [] entry_SYSCALL_64_fastpath+0x1e/0x9a [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621 [] sel_commit_bools_write+0x89/0x260 security/selinux/selinuxfs.c:1142 [] __vfs_write+0x116/0x3d0 fs/read_write.c:491 [] __kernel_write+0x112/0x370 fs/read_write.c:513 [] write_pipe_buf+0x15d/0x1f0 fs/splice.c:1074 audit_printk_skb: 18 callbacks suppressed audit: type=1400 audit(1568012659.715:1282): avc: denied { write } for pid=16310 comm="syz-executor.3" 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 [] splice_from_pipe_feed fs/splice.c:776 [inline] [] __splice_from_pipe+0x37e/0x7a0 fs/splice.c:901 [] splice_from_pipe+0x108/0x170 fs/splice.c:936 [] default_file_splice_write+0x3c/0x80 fs/splice.c:1086 [] do_splice_from fs/splice.c:1128 [inline] [] do_splice fs/splice.c:1404 [inline] [] SYSC_splice fs/splice.c:1707 [inline] [] SyS_splice+0xd71/0x13a0 fs/splice.c:1690 [] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] [] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397 [] sysenter_flags_fixed+0xd/0x1a [] check_prev_add kernel/locking/lockdep.c:1853 [inline] [] check_prevs_add kernel/locking/lockdep.c:1958 [inline] [] validate_chain kernel/locking/lockdep.c:2144 [inline] [] __lock_acquire+0x37d6/0x4f50 kernel/locking/lockdep.c:3213 [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621 [] pipe_lock_nested fs/pipe.c:65 [inline] [] pipe_lock+0x63/0x80 fs/pipe.c:73 [] iter_file_splice_write+0x179/0xb30 fs/splice.c:974 [] do_splice_from fs/splice.c:1128 [inline] [] do_splice fs/splice.c:1404 [inline] [] SYSC_splice fs/splice.c:1707 [inline] [] SyS_splice+0xd71/0x13a0 fs/splice.c:1690 [] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] [] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397 audit: type=1400 audit(1568012659.835:1283): avc: denied { read } for pid=16310 comm="syz-executor.3" 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 [] sysenter_flags_fixed+0xd/0x1a audit: type=1400 audit(1568012659.865:1284): avc: denied { create } for pid=16310 comm="syz-executor.3" 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 audit: type=1400 audit(1568012659.865:1285): avc: denied { write } for pid=16310 comm="syz-executor.3" 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 audit: type=1400 audit(1568012659.885:1286): avc: denied { read } for pid=16310 comm="syz-executor.3" 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 other info that might help us debug this: Chain exists of: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_writers#4); lock(&eli->li_list_mtx); lock(sb_writers#4); lock(&pipe->mutex/1); *** DEADLOCK *** 1 lock held by syz-executor.5/16314: #0: (sb_writers#4){.+.+.+}, at: [] file_start_write include/linux/fs.h:2543 [inline] #0: (sb_writers#4){.+.+.+}, at: [] do_splice fs/splice.c:1403 [inline] #0: (sb_writers#4){.+.+.+}, at: [] SYSC_splice fs/splice.c:1707 [inline] #0: (sb_writers#4){.+.+.+}, at: [] SyS_splice+0xf2d/0x13a0 fs/splice.c:1690 stack backtrace: CPU: 1 PID: 16314 Comm: syz-executor.5 Not tainted 4.4.174+ #17 0000000000000000 0144692cba44d3b7 ffff8801d3bbf840 ffffffff81aad1a1 ffffffff84057a80 ffff8800b3c25f00 ffffffff83abd2b0 ffffffff83abc380 ffffffff83ac8080 ffff8801d3bbf890 ffffffff813abcda ffffffff83e1eb80 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [] print_circular_bug.cold+0x2f7/0x44e kernel/locking/lockdep.c:1226 [] check_prev_add kernel/locking/lockdep.c:1853 [inline] [] check_prevs_add kernel/locking/lockdep.c:1958 [inline] [] validate_chain kernel/locking/lockdep.c:2144 [inline] [] __lock_acquire+0x37d6/0x4f50 kernel/locking/lockdep.c:3213 [] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592 [] __mutex_lock_common kernel/locking/mutex.c:521 [inline] [] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621 [] pipe_lock_nested fs/pipe.c:65 [inline] [] pipe_lock+0x63/0x80 fs/pipe.c:73 [] iter_file_splice_write+0x179/0xb30 fs/splice.c:974 [] do_splice_from fs/splice.c:1128 [inline] [] do_splice fs/splice.c:1404 [inline] [] SYSC_splice fs/splice.c:1707 [inline] [] SyS_splice+0xd71/0x13a0 fs/splice.c:1690 [] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] [] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397 [] sysenter_flags_fixed+0xd/0x1a audit: type=1400 audit(1568012660.475:1287): avc: denied { create } for pid=16340 comm="syz-executor.4" 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 audit: type=1400 audit(1568012660.575:1288): avc: denied { write } for pid=16340 comm="syz-executor.4" 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 audit: type=1400 audit(1568012660.755:1289): avc: denied { read } for pid=16340 comm="syz-executor.4" 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 audit: type=1400 audit(1568012660.915:1290): avc: denied { create } for pid=16368 comm="syz-executor.2" 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 audit: type=1400 audit(1568012660.955:1291): avc: denied { write } for pid=16368 comm="syz-executor.2" 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 input: syz1 as /devices/virtual/input/input52 input: syz1 as /devices/virtual/input/input53 audit_printk_skb: 108 callbacks suppressed audit: type=1400 audit(1568012664.855:1328): avc: denied { create } for pid=16507 comm="syz-executor.4" 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: unrecognized netlink message: protocol=0 nlmsg_type=257 sclass=netlink_route_socket audit: type=1400 audit(1568012664.995:1329): avc: denied { write } for pid=16507 comm="syz-executor.4" 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 audit: type=1400 audit(1568012665.035:1330): avc: denied { create } for pid=16504 comm="syz-executor.5" 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 audit: type=1400 audit(1568012665.065:1331): avc: denied { create } for pid=16528 comm="syz-executor.2" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_netfilter_socket permissive=1 audit: type=1400 audit(1568012665.095:1332): avc: denied { write } for pid=16504 comm="syz-executor.5" 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 audit: type=1400 audit(1568012665.265:1333): avc: denied { read } for pid=16507 comm="syz-executor.4" 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 audit: type=1400 audit(1568012665.365:1334): avc: denied { create } for pid=16507 comm="syz-executor.4" 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 audit: type=1400 audit(1568012665.405:1335): avc: denied { create } for pid=16546 comm="syz-executor.2" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_netfilter_socket permissive=1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=257 sclass=netlink_route_socket audit: type=1400 audit(1568012665.535:1336): avc: denied { create } for pid=16547 comm="syz-executor.5" 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 audit: type=1400 audit(1568012665.615:1337): avc: denied { write } for pid=16547 comm="syz-executor.5" 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