WARNING: possible circular locking dependency detected 4.14.99+ #10 Not tainted ------------------------------------------------------ syz-executor.3/6081 is trying to acquire lock: (&sig->cred_guard_mutex){+.+.}, at: [] proc_pid_attr_write+0x152/0x280 fs/proc/base.c:2590 but task is already holding lock: (&pipe->mutex/1){+.+.}, at: [] pipe_lock_nested fs/pipe.c:67 [inline] (&pipe->mutex/1){+.+.}, at: [] pipe_lock+0x58/0x70 fs/pipe.c:75 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: audit: type=1400 audit(1550093955.556:2922): avc: denied { map } for pid=6071 comm="blkid" path="/etc/ld.so.cache" dev="sda1" ino=2503 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 -> #1 (&pipe->mutex/1){+.+.}: -> #0 (&sig->cred_guard_mutex){+.+.}: other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&pipe->mutex/1); lock(&sig->cred_guard_mutex); lock(&pipe->mutex/1); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 2 locks held by syz-executor.3/6081: #0: (sb_writers#7){.+.+}, at: [] file_start_write include/linux/fs.h:2726 [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+0xec1/0x12d0 fs/splice.c:1382 #1: (&pipe->mutex/1){+.+.}, at: [] pipe_lock_nested fs/pipe.c:67 [inline] #1: (&pipe->mutex/1){+.+.}, at: [] pipe_lock+0x58/0x70 fs/pipe.c:75 stack backtrace: CPU: 0 PID: 6081 Comm: syz-executor.3 Not tainted 4.14.99+ #10 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 audit: type=1400 audit(1550093955.556:2923): avc: denied { map } for pid=6071 comm="blkid" path="/lib/x86_64-linux-gnu/libblkid.so.1.1.0" dev="sda1" ino=2825 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093955.586:2924): avc: denied { map } for pid=6073 comm="blkid" path="/etc/ld.so.cache" dev="sda1" ino=2503 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093955.596:2925): avc: denied { map } for pid=6071 comm="blkid" path="/lib/x86_64-linux-gnu/libc-2.13.so" dev="sda1" ino=2784 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093955.596:2926): avc: denied { map } for pid=6073 comm="blkid" path="/lib/x86_64-linux-gnu/libblkid.so.1.1.0" dev="sda1" ino=2825 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093955.606:2928): avc: denied { map } for pid=6071 comm="blkid" path="/lib/x86_64-linux-gnu/libc-2.13.so" dev="sda1" ino=2784 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 EXT4-fs (loop0): VFS: Can't find ext4 filesystem audit: type=1400 audit(1550093955.606:2927): avc: denied { map } for pid=6073 comm="blkid" path="/lib/x86_64-linux-gnu/libblkid.so.1.1.0" dev="sda1" ino=2825 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093955.616:2929): avc: denied { map } for pid=6073 comm="blkid" path="/lib/x86_64-linux-gnu/libc-2.13.so" dev="sda1" ino=2784 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem kauditd_printk_skb: 444 callbacks suppressed audit: type=1400 audit(1550093960.556:3375): avc: denied { map } for pid=6252 comm="blkid" path="/lib/x86_64-linux-gnu/ld-2.13.so" dev="sda1" ino=2668 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093960.556:3376): avc: denied { map } for pid=6252 comm="blkid" path="/lib/x86_64-linux-gnu/ld-2.13.so" dev="sda1" ino=2668 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093960.556:3374): avc: denied { map } for pid=6250 comm="blkid" path="/etc/ld.so.cache" dev="sda1" ino=2503 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093960.596:3377): avc: denied { map } for pid=6250 comm="blkid" path="/lib/x86_64-linux-gnu/libblkid.so.1.1.0" dev="sda1" ino=2825 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 EXT4-fs (loop0): VFS: Can't find ext4 filesystem audit: type=1400 audit(1550093960.606:3378): avc: denied { map } for pid=6250 comm="blkid" path="/lib/x86_64-linux-gnu/libblkid.so.1.1.0" dev="sda1" ino=2825 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093960.606:3379): avc: denied { map } for pid=6252 comm="blkid" path="/etc/ld.so.cache" dev="sda1" ino=2503 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093960.626:3380): avc: denied { map } for pid=6250 comm="blkid" path="/lib/x86_64-linux-gnu/libc-2.13.so" dev="sda1" ino=2784 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093960.626:3381): avc: denied { map } for pid=6250 comm="blkid" path="/lib/x86_64-linux-gnu/libc-2.13.so" dev="sda1" ino=2784 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 EXT4-fs (loop0): VFS: Can't find ext4 filesystem audit: type=1400 audit(1550093960.636:3382): avc: denied { map } for pid=6252 comm="blkid" path="/lib/x86_64-linux-gnu/libblkid.so.1.1.0" dev="sda1" ino=2825 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1550093960.646:3383): avc: denied { map } for pid=6250 comm="blkid" path="/lib/x86_64-linux-gnu/libuuid.so.1.3.0" dev="sda1" ino=2819 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem EXT4-fs (loop0): VFS: Can't find ext4 filesystem