audit: type=1400 audit(1539634491.780:8): avc: denied { associate } for pid=2071 comm="syz-executor3" name="syz3" scontext=unconfined_u:object_r:unlabeled_t:s0 tcontext=system_u:object_r:unlabeled_t:s0 tclass=filesystem permissive=1 audit: type=1400 audit(1539634501.510:9): avc: denied { dac_override } for pid=6238 comm="syz-executor1" capability=1 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 ====================================================== [ INFO: possible circular locking dependency detected ] 4.9.133+ #6 Not tainted ------------------------------------------------------- syz-executor1/6242 is trying to acquire lock: (&sig->cred_guard_mutex){+.+.+.}, at: [] lock_trace+0x44/0xc0 fs/proc/base.c:431 but task is already holding lock: (&p->lock){+.+.+.}, at: [] seq_read+0xdd/0x12d0 fs/seq_file.c:178 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756 __mutex_lock_common kernel/locking/mutex.c:521 [inline] mutex_lock_nested+0xc0/0x900 kernel/locking/mutex.c:621 seq_read+0xdd/0x12d0 fs/seq_file.c:178 proc_reg_read+0xfd/0x180 fs/proc/inode.c:203 do_loop_readv_writev.part.1+0xd5/0x280 fs/read_write.c:718 do_loop_readv_writev fs/read_write.c:707 [inline] do_readv_writev+0x56e/0x7b0 fs/read_write.c:873 vfs_readv+0x84/0xc0 fs/read_write.c:897 kernel_readv fs/splice.c:363 [inline] default_file_splice_read+0x451/0x7f0 fs/splice.c:435 do_splice_to+0x10c/0x170 fs/splice.c:899 do_splice fs/splice.c:1192 [inline] SYSC_splice fs/splice.c:1416 [inline] SyS_splice+0x10d2/0x14d0 fs/splice.c:1399 do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390 entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756 __mutex_lock_common kernel/locking/mutex.c:521 [inline] mutex_lock_nested+0xc0/0x900 kernel/locking/mutex.c:621 __pipe_lock fs/pipe.c:87 [inline] fifo_open+0x15c/0x9e0 fs/pipe.c:921 do_dentry_open+0x3ef/0xc90 fs/open.c:766 vfs_open+0x11c/0x210 fs/open.c:879 do_last fs/namei.c:3410 [inline] path_openat+0x542/0x2790 fs/namei.c:3534 do_filp_open+0x197/0x270 fs/namei.c:3568 do_open_execat+0x10f/0x640 fs/exec.c:844 do_execveat_common.isra.14+0x687/0x1ed0 fs/exec.c:1723 compat_do_execve fs/exec.c:1856 [inline] C_SYSC_execve fs/exec.c:1931 [inline] compat_SyS_execve+0x48/0x60 fs/exec.c:1927 do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390 entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 check_prev_add kernel/locking/lockdep.c:1828 [inline] check_prevs_add kernel/locking/lockdep.c:1938 [inline] validate_chain kernel/locking/lockdep.c:2265 [inline] __lock_acquire+0x3189/0x4a10 kernel/locking/lockdep.c:3345 lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756 __mutex_lock_common kernel/locking/mutex.c:521 [inline] mutex_lock_killable_nested+0xcc/0x9f0 kernel/locking/mutex.c:641 lock_trace+0x44/0xc0 fs/proc/base.c:431 proc_pid_syscall+0xa9/0x260 fs/proc/base.c:663 proc_single_show+0xfd/0x170 fs/proc/base.c:785 seq_read+0x4b6/0x12d0 fs/seq_file.c:240 do_loop_readv_writev.part.1+0xd5/0x280 fs/read_write.c:718 do_loop_readv_writev fs/read_write.c:707 [inline] do_readv_writev+0x56e/0x7b0 fs/read_write.c:873 vfs_readv+0x84/0xc0 fs/read_write.c:897 kernel_readv fs/splice.c:363 [inline] default_file_splice_read+0x451/0x7f0 fs/splice.c:435 do_splice_to+0x10c/0x170 fs/splice.c:899 splice_direct_to_actor+0x23f/0x7e0 fs/splice.c:971 do_splice_direct+0x1a3/0x270 fs/splice.c:1080 do_sendfile+0x4f0/0xc30 fs/read_write.c:1393 C_SYSC_sendfile fs/read_write.c:1469 [inline] compat_SyS_sendfile+0xd1/0x160 fs/read_write.c:1458 do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390 entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 other info that might help us debug this: Chain exists of: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); lock(&pipe->mutex/1); lock(&p->lock); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 2 locks held by syz-executor1/6242: #0: (sb_writers#7){.+.+.+}, at: [] file_start_write include/linux/fs.h:2640 [inline] #0: (sb_writers#7){.+.+.+}, at: [] do_sendfile+0xa80/0xc30 fs/read_write.c:1392 #1: (&p->lock){+.+.+.}, at: [] seq_read+0xdd/0x12d0 fs/seq_file.c:178 stack backtrace: CPU: 1 PID: 6242 Comm: syz-executor1 Not tainted 4.9.133+ #6 ffff8801c9ec6e28 ffffffff81b37069 ffffffff83caa7a0 ffffffff83ca4e30