audit: type=1400 audit(1541277656.098:721): avc:  denied  { create } for  pid=25578 comm="syz-executor4" 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

======================================================
[ INFO: possible circular locking dependency detected ]
4.4.162+ #117 Not tainted
-------------------------------------------------------
syz-executor2/25609 is trying to acquire lock:
 (&pipe->mutex/1){+.+.+.}, at: [<ffffffff814a9afe>] pipe_lock_nested fs/pipe.c:65 [inline]
 (&pipe->mutex/1){+.+.+.}, at: [<ffffffff814a9afe>] pipe_lock+0x5e/0x70 fs/pipe.c:73

but task is already holding lock:
 (sb_writers#4){.+.+.+}, at: [<ffffffff8153134a>] file_start_write include/linux/fs.h:2541 [inline]
 (sb_writers#4){.+.+.+}, at: [<ffffffff8153134a>] do_splice fs/splice.c:1403 [inline]
 (sb_writers#4){.+.+.+}, at: [<ffffffff8153134a>] SYSC_splice fs/splice.c:1707 [inline]
 (sb_writers#4){.+.+.+}, at: [<ffffffff8153134a>] SyS_splice+0xfaa/0x1430 fs/splice.c:1690

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

       [<ffffffff81202cde>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff81498cae>] percpu_down_read include/linux/percpu-rwsem.h:26 [inline]
       [<ffffffff81498cae>] __sb_start_write+0x1ae/0x310 fs/super.c:1221
       [<ffffffff816bafc7>] sb_start_write include/linux/fs.h:1515 [inline]
       [<ffffffff816bafc7>] ext4_run_li_request fs/ext4/super.c:2674 [inline]
       [<ffffffff816bafc7>] ext4_lazyinit_thread+0x1a7/0x750 fs/ext4/super.c:2773
       [<ffffffff81133e18>] kthread+0x268/0x300 kernel/kthread.c:211
       [<ffffffff827066c5>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510

       [<ffffffff81202cde>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff826fad9b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff826fad9b>] mutex_lock_nested+0xbb/0x8d0 kernel/locking/mutex.c:621
       [<ffffffff816c50c4>] ext4_register_li_request+0x304/0x7a0 fs/ext4/super.c:2961
       [<ffffffff816c68c8>] ext4_remount+0x1368/0x1bb0 fs/ext4/super.c:4911
       [<ffffffff8149bf58>] do_remount_sb2+0x428/0x7d0 fs/super.c:771
       [<ffffffff814fbe9e>] do_remount fs/namespace.c:2335 [inline]
       [<ffffffff814fbe9e>] do_mount+0x101e/0x2a10 fs/namespace.c:2848
       [<ffffffff814fe3e1>] SYSC_mount fs/namespace.c:3051 [inline]
       [<ffffffff814fe3e1>] SyS_mount+0x191/0x1c0 fs/namespace.c:3029
       [<ffffffff827062e1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

       [<ffffffff81202cde>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff826fad9b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff826fad9b>] mutex_lock_nested+0xbb/0x8d0 kernel/locking/mutex.c:621
       [<ffffffff816c4e47>] ext4_register_li_request+0x87/0x7a0 fs/ext4/super.c:2934
       [<ffffffff816c68c8>] ext4_remount+0x1368/0x1bb0 fs/ext4/super.c:4911
       [<ffffffff8149bf58>] do_remount_sb2+0x428/0x7d0 fs/super.c:771
       [<ffffffff814fbe9e>] do_remount fs/namespace.c:2335 [inline]
       [<ffffffff814fbe9e>] do_mount+0x101e/0x2a10 fs/namespace.c:2848
       [<ffffffff814fe3e1>] SYSC_mount fs/namespace.c:3051 [inline]
       [<ffffffff814fe3e1>] SyS_mount+0x191/0x1c0 fs/namespace.c:3029
       [<ffffffff827062e1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

       [<ffffffff81202cde>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff82701312>] down_read+0x42/0x60 kernel/locking/rwsem.c:22
       [<ffffffff8149b671>] iterate_supers+0xe1/0x260 fs/super.c:537
       [<ffffffff8199e104>] selinux_complete_init+0x2f/0x31 security/selinux/hooks.c:6154
       [<ffffffff8198fd56>] security_load_policy+0x886/0x9b0 security/selinux/ss/services.c:2060
       [<ffffffff81965c81>] sel_write_load+0x191/0xfc0 security/selinux/selinuxfs.c:535
       [<ffffffff81490c1c>] __vfs_write+0x11c/0x3e0 fs/read_write.c:489
       [<ffffffff814928ce>] vfs_write+0x17e/0x4e0 fs/read_write.c:538
       [<ffffffff81494f09>] SYSC_write fs/read_write.c:585 [inline]
       [<ffffffff81494f09>] SyS_write+0xd9/0x1c0 fs/read_write.c:577
       [<ffffffff827062e1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

       [<ffffffff81202cde>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff826fad9b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff826fad9b>] mutex_lock_nested+0xbb/0x8d0 kernel/locking/mutex.c:621
       [<ffffffff81963767>] sel_commit_bools_write+0x87/0x250 security/selinux/selinuxfs.c:1142
       [<ffffffff81490c1c>] __vfs_write+0x11c/0x3e0 fs/read_write.c:489
       [<ffffffff81490fea>] __kernel_write+0x10a/0x350 fs/read_write.c:511
       [<ffffffff8152c05d>] write_pipe_buf+0x15d/0x1f0 fs/splice.c:1074
       [<ffffffff8152cef4>] splice_from_pipe_feed fs/splice.c:776 [inline]
       [<ffffffff8152cef4>] __splice_from_pipe+0x364/0x790 fs/splice.c:901
       [<ffffffff8152ffb9>] splice_from_pipe+0xf9/0x170 fs/splice.c:936
       [<ffffffff815300bc>] default_file_splice_write+0x3c/0x80 fs/splice.c:1086
       [<ffffffff81531181>] do_splice_from fs/splice.c:1128 [inline]
       [<ffffffff81531181>] do_splice fs/splice.c:1404 [inline]
       [<ffffffff81531181>] SYSC_splice fs/splice.c:1707 [inline]
       [<ffffffff81531181>] SyS_splice+0xde1/0x1430 fs/splice.c:1690
       [<ffffffff827062e1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

       [<ffffffff811ff0fc>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
       [<ffffffff811ff0fc>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
       [<ffffffff811ff0fc>] validate_chain kernel/locking/lockdep.c:2144 [inline]
       [<ffffffff811ff0fc>] __lock_acquire+0x3e6c/0x5f10 kernel/locking/lockdep.c:3213
       [<ffffffff81202cde>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff826fad9b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff826fad9b>] mutex_lock_nested+0xbb/0x8d0 kernel/locking/mutex.c:621
       [<ffffffff814a9afe>] pipe_lock_nested fs/pipe.c:65 [inline]
       [<ffffffff814a9afe>] pipe_lock+0x5e/0x70 fs/pipe.c:73
       [<ffffffff8152d660>] iter_file_splice_write+0x160/0xb90 fs/splice.c:974
       [<ffffffff81531181>] do_splice_from fs/splice.c:1128 [inline]
       [<ffffffff81531181>] do_splice fs/splice.c:1404 [inline]
       [<ffffffff81531181>] SYSC_splice fs/splice.c:1707 [inline]
       [<ffffffff81531181>] SyS_splice+0xde1/0x1430 fs/splice.c:1690
       [<ffffffff827062e1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

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-executor2/25609:
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff8153134a>] file_start_write include/linux/fs.h:2541 [inline]
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff8153134a>] do_splice fs/splice.c:1403 [inline]
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff8153134a>] SYSC_splice fs/splice.c:1707 [inline]
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff8153134a>] SyS_splice+0xfaa/0x1430 fs/splice.c:1690

stack backtrace:
CPU: 0 PID: 25609 Comm: syz-executor2 Not tainted 4.4.162+ #117
 0000000000000000 ded63e75cc32ecf7 ffff8801d3717908 ffffffff81a994bd
 ffffffff83ac0040 ffffffff83ab4340 ffffffff83ab5270 ffff8800bab267e8
 ffff8800bab25f00 ffff8801d3717950 ffffffff813a834a 0000000000000001
Call Trace:
 [<ffffffff81a994bd>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81a994bd>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff813a834a>] print_circular_bug.cold.34+0x2f7/0x432 kernel/locking/lockdep.c:1226
 [<ffffffff811ff0fc>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
 [<ffffffff811ff0fc>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
 [<ffffffff811ff0fc>] validate_chain kernel/locking/lockdep.c:2144 [inline]
 [<ffffffff811ff0fc>] __lock_acquire+0x3e6c/0x5f10 kernel/locking/lockdep.c:3213
 [<ffffffff81202cde>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
 [<ffffffff826fad9b>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
 [<ffffffff826fad9b>] mutex_lock_nested+0xbb/0x8d0 kernel/locking/mutex.c:621
 [<ffffffff814a9afe>] pipe_lock_nested fs/pipe.c:65 [inline]
 [<ffffffff814a9afe>] pipe_lock+0x5e/0x70 fs/pipe.c:73
 [<ffffffff8152d660>] iter_file_splice_write+0x160/0xb90 fs/splice.c:974
 [<ffffffff81531181>] do_splice_from fs/splice.c:1128 [inline]
 [<ffffffff81531181>] do_splice fs/splice.c:1404 [inline]
 [<ffffffff81531181>] SYSC_splice fs/splice.c:1707 [inline]
 [<ffffffff81531181>] SyS_splice+0xde1/0x1430 fs/splice.c:1690
 [<ffffffff827062e1>] entry_SYSCALL_64_fastpath+0x1e/0x9a
SELinux: ebitmap: map size 2427262366 does not match my size 64 (high bit was -1880380919)
audit: type=1400 audit(1541277657.588:722): avc:  denied  { create } for  pid=25635 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_generic_socket permissive=1
audit: type=1400 audit(1541277657.668:723): avc:  denied  { write } for  pid=25635 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_generic_socket permissive=1
audit: type=1400 audit(1541277657.878:724): avc:  denied  { read } for  pid=25635 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_generic_socket permissive=1
audit: type=1400 audit(1541277657.948:725): avc:  denied  { create } for  pid=25650 comm="syz-executor0" 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=6 nlmsg_type=0 sclass=netlink_xfrm_socket
audit_printk_skb: 72 callbacks suppressed
audit: type=1400 audit(1541277660.308:750): avc:  denied  { create } for  pid=25761 comm="syz-executor0" 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(1541277660.398:751): avc:  denied  { write } for  pid=25761 comm="syz-executor0" 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(1541277660.538:752): avc:  denied  { read } for  pid=25761 comm="syz-executor0" 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(1541277660.848:753): avc:  denied  { create } for  pid=25787 comm="syz-executor0" 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(1541277660.908:754): avc:  denied  { write } for  pid=25787 comm="syz-executor0" 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(1541277661.088:755): avc:  denied  { read } for  pid=25787 comm="syz-executor0" 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(1541277661.508:756): avc:  denied  { create } for  pid=25810 comm="syz-executor0" 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(1541277661.578:757): avc:  denied  { write } for  pid=25810 comm="syz-executor0" 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(1541277661.648:758): avc:  denied  { create } for  pid=25822 comm="syz-executor5" 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(1541277661.678:759): avc:  denied  { read } for  pid=25810 comm="syz-executor0" 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_printk_skb: 51 callbacks suppressed
audit: type=1400 audit(1541277665.578:777): avc:  denied  { create } for  pid=25980 comm="syz-executor5" 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(1541277665.618:778): avc:  denied  { write } for  pid=25980 comm="syz-executor5" 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(1541277665.668:779): avc:  denied  { read } for  pid=25980 comm="syz-executor5" 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(1541277666.148:780): avc:  denied  { create } for  pid=26005 comm="syz-executor5" 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(1541277666.248:781): avc:  denied  { write } for  pid=26005 comm="syz-executor5" 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(1541277666.368:782): avc:  denied  { read } for  pid=26005 comm="syz-executor5" 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