[ 36.304927][ T26] audit: type=1800 audit(1550671241.835:27): pid=7600 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 36.325733][ T26] audit: type=1800 audit(1550671241.835:28): pid=7600 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="ssh" dev="sda1" ino=2417 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. [ 36.993004][ T26] audit: type=1800 audit(1550671242.575:29): pid=7600 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="rc.local" dev="sda1" ino=2432 res=0 [ 37.013146][ T26] audit: type=1800 audit(1550671242.575:30): pid=7600 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="rmnologin" dev="sda1" ino=2423 res=0 Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.40' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 47.249493][ T7757] [ 47.251836][ T7757] ====================================================== [ 47.258840][ T7757] WARNING: possible circular locking dependency detected [ 47.265831][ T7757] 5.0.0-rc7-next-20190220 #39 Not tainted [ 47.271517][ T7757] ------------------------------------------------------ [ 47.278539][ T7757] syz-executor146/7757 is trying to acquire lock: [ 47.284923][ T7757] 00000000c2b211d3 (&sig->cred_guard_mutex){+.+.}, at: proc_pid_attr_write+0x200/0x580 [ 47.294542][ T7757] [ 47.294542][ T7757] but task is already holding lock: [ 47.301896][ T7757] 00000000f5c8291b (&pipe->mutex/1){+.+.}, at: pipe_lock+0x6e/0x80 [ 47.309768][ T7757] [ 47.309768][ T7757] which lock already depends on the new lock. [ 47.309768][ T7757] [ 47.320156][ T7757] [ 47.320156][ T7757] the existing dependency chain (in reverse order) is: [ 47.329155][ T7757] [ 47.329155][ T7757] -> #1 (&pipe->mutex/1){+.+.}: [ 47.336168][ T7757] __mutex_lock+0xf7/0x1310 [ 47.341169][ T7757] mutex_lock_nested+0x16/0x20 [ 47.346429][ T7757] fifo_open+0x159/0xb00 [ 47.351168][ T7757] do_dentry_open+0x488/0x1160 [ 47.356426][ T7757] vfs_open+0xa0/0xd0 [ 47.360918][ T7757] path_openat+0x10e9/0x46e0 [ 47.366002][ T7757] do_filp_open+0x1a1/0x280 [ 47.371004][ T7757] do_open_execat+0x137/0x690 [ 47.376179][ T7757] __do_execve_file.isra.0+0x178d/0x23f0 [ 47.382304][ T7757] __x64_sys_execve+0x8f/0xc0 [ 47.387479][ T7757] do_syscall_64+0x103/0x610 [ 47.392565][ T7757] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 47.398947][ T7757] [ 47.398947][ T7757] -> #0 (&sig->cred_guard_mutex){+.+.}: [ 47.406665][ T7757] lock_acquire+0x16f/0x3f0 [ 47.411679][ T7757] __mutex_lock+0xf7/0x1310 [ 47.416692][ T7757] mutex_lock_interruptible_nested+0x16/0x20 [ 47.423184][ T7757] proc_pid_attr_write+0x200/0x580 [ 47.428807][ T7757] __vfs_write+0x8d/0x110 [ 47.433643][ T7757] __kernel_write+0x110/0x3b0 [ 47.438833][ T7757] write_pipe_buf+0x15d/0x1f0 [ 47.444022][ T7757] __splice_from_pipe+0x395/0x7d0 [ 47.449558][ T7757] splice_from_pipe+0x108/0x170 [ 47.454918][ T7757] default_file_splice_write+0x3c/0x90 [ 47.460889][ T7757] do_splice+0x644/0x1260 [ 47.465727][ T7757] __x64_sys_splice+0x2c6/0x330 [ 47.471089][ T7757] do_syscall_64+0x103/0x610 [ 47.476192][ T7757] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 47.482588][ T7757] [ 47.482588][ T7757] other info that might help us debug this: [ 47.482588][ T7757] [ 47.492803][ T7757] Possible unsafe locking scenario: [ 47.492803][ T7757] [ 47.500242][ T7757] CPU0 CPU1 [ 47.505589][ T7757] ---- ---- [ 47.510937][ T7757] lock(&pipe->mutex/1); [ 47.515255][ T7757] lock(&sig->cred_guard_mutex); [ 47.522786][ T7757] lock(&pipe->mutex/1); [ 47.529622][ T7757] lock(&sig->cred_guard_mutex); [ 47.534632][ T7757] [ 47.534632][ T7757] *** DEADLOCK *** [ 47.534632][ T7757] [ 47.543217][ T7757] 2 locks held by syz-executor146/7757: [ 47.548743][ T7757] #0: 000000004faff977 (sb_writers#6){.+.+}, at: do_splice+0xcf4/0x1260 [ 47.557164][ T7757] #1: 00000000f5c8291b (&pipe->mutex/1){+.+.}, at: pipe_lock+0x6e/0x80 [ 47.565490][ T7757] [ 47.565490][ T7757] stack backtrace: [ 47.571376][ T7757] CPU: 0 PID: 7757 Comm: syz-executor146 Not tainted 5.0.0-rc7-next-20190220 #39 [ 47.580463][ T7757] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 47.590501][ T7757] Call Trace: [ 47.593788][ T7757] dump_stack+0x172/0x1f0 [ 47.598113][ T7757] print_circular_bug.isra.0.cold+0x1cc/0x28f [ 47.604188][ T7757] __lock_acquire+0x2fca/0x4710 [ 47.609033][ T7757] ? trace_hardirqs_on+0x67/0x230 [ 47.614049][ T7757] ? kasan_check_read+0x11/0x20 [ 47.618891][ T7757] ? mark_held_locks+0xf0/0xf0 [ 47.623647][ T7757] ? __kmalloc_track_caller+0x158/0x740 [ 47.629182][ T7757] ? memdup_user+0x26/0xb0 [ 47.633587][ T7757] ? proc_pid_attr_write+0x19c/0x580 [ 47.638863][ T7757] ? __vfs_write+0x8d/0x110 [ 47.643355][ T7757] ? __kernel_write+0x110/0x3b0 [ 47.648477][ T7757] ? write_pipe_buf+0x15d/0x1f0 [ 47.653319][ T7757] ? __splice_from_pipe+0x395/0x7d0 [ 47.658513][ T7757] ? do_syscall_64+0x103/0x610 [ 47.663271][ T7757] ? add_lock_to_list.isra.0+0x17c/0x330 [ 47.668893][ T7757] lock_acquire+0x16f/0x3f0 [ 47.673388][ T7757] ? proc_pid_attr_write+0x200/0x580 [ 47.678665][ T7757] ? proc_pid_attr_write+0x200/0x580 [ 47.683949][ T7757] __mutex_lock+0xf7/0x1310 [ 47.688441][ T7757] ? proc_pid_attr_write+0x200/0x580 [ 47.693714][ T7757] ? proc_pid_attr_write+0x200/0x580 [ 47.698992][ T7757] ? mutex_trylock+0x1e0/0x1e0 [ 47.703748][ T7757] ? check_stack_object+0x114/0x160 [ 47.708935][ T7757] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 47.715178][ T7757] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 47.721407][ T7757] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 47.727636][ T7757] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 47.733874][ T7757] ? _copy_from_user+0xdd/0x150 [ 47.738718][ T7757] mutex_lock_interruptible_nested+0x16/0x20 [ 47.744688][ T7757] ? mutex_lock_interruptible_nested+0x16/0x20 [ 47.750849][ T7757] proc_pid_attr_write+0x200/0x580 [ 47.755953][ T7757] __vfs_write+0x8d/0x110 [ 47.760277][ T7757] ? proc_loginuid_write+0x4d0/0x4d0 [ 47.765556][ T7757] __kernel_write+0x110/0x3b0 [ 47.770231][ T7757] write_pipe_buf+0x15d/0x1f0 [ 47.774901][ T7757] ? do_splice_direct+0x2a0/0x2a0 [ 47.779915][ T7757] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 47.786167][ T7757] ? splice_from_pipe_next.part.0+0x255/0x2f0 [ 47.792229][ T7757] __splice_from_pipe+0x395/0x7d0 [ 47.797340][ T7757] ? do_splice_direct+0x2a0/0x2a0 [ 47.802360][ T7757] ? do_splice_direct+0x2a0/0x2a0 [ 47.807373][ T7757] splice_from_pipe+0x108/0x170 [ 47.812214][ T7757] ? splice_shrink_spd+0xd0/0xd0 [ 47.817163][ T7757] default_file_splice_write+0x3c/0x90 [ 47.822610][ T7757] ? generic_splice_sendpage+0x50/0x50 [ 47.828063][ T7757] do_splice+0x644/0x1260 [ 47.832385][ T7757] ? opipe_prep.part.0+0x2d0/0x2d0 [ 47.837491][ T7757] ? __fget_light+0x1a9/0x230 [ 47.842184][ T7757] __x64_sys_splice+0x2c6/0x330 [ 47.847026][ T7757] do_syscall_64+0x103/0x610 [ 47.851610][ T7757] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 47.857491][ T7757] RIP: 0033:0x445779 [ 47.861380][ T7757] Code: e8 6c b6 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 2b 12 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 47.880986][ T7757] RSP: 002b:00007fe969e9ada8 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 [ 47.889385][ T7757] RAX: ffffffffffffffda RBX: 00000000006dac68 RCX: 0000000000445779 [ 47.897343][ T7757] RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003 [ 47.905301][ T7757] RBP: 00000000006dac60 R08: 0000020000000003 R09: 0000000000000009 [ 47.913262][ T7757] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac6c [ 47.921224][ T7757] R13: 00007fff981fceff R14: 00007fe969e9b9c0 R15: 20c49ba5e353f7cf