[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c.
Starting mcstransd: 
[....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c.
[....] Starting OpenBSD Secure Shell server: sshd[   11.657102] random: sshd: uninitialized urandom read (32 bytes read)
[?25l[?1c7[ ok 8[?25h[?0c.
[   11.806499] random: crng init done

Debian GNU/Linux 7 syzkaller ttyS0

Warning: Permanently added '10.128.0.30' (ECDSA) to the list of known hosts.
executing program
executing program
syzkaller login: [   38.602669] 
[   38.603213] ======================================================
[   38.604374] [ INFO: possible circular locking dependency detected ]
[   38.605394] 4.9.128+ #41 Not tainted
[   38.605925] -------------------------------------------------------
[   38.607046] syz-executor842/2060 is trying to acquire lock:
[   38.607916]  (&p->lock){+.+.+.}, at: [<ffffffff8155eafd>] seq_read+0xdd/0x12d0

[   38.609289] but task is already holding lock:
[   38.610098]  (&pipe->mutex/1){+.+.+.}, at: [<ffffffff815044be>] pipe_lock+0x5e/0x70

[   38.611432] which lock already depends on the new lock.
[   38.611432] 
[   38.612549] 
[   38.612549] the existing dependency chain (in reverse order) is:
[   38.613741] 
-> #2 (&pipe->mutex/1){+.+.+.}:
[   38.614642]        lock_acquire+0x130/0x3e0
[   38.615415]        mutex_lock_nested+0xc0/0x870
[   38.616174]        fifo_open+0x15c/0x9e0
[   38.616764]        do_dentry_open+0x3ef/0xc90
[   38.617459]        vfs_open+0x11c/0x210
[   38.618046]        path_openat+0x542/0x2790
[   38.618758]        do_filp_open+0x197/0x270
[   38.619590]        do_open_execat+0x10f/0x640
[   38.620262]        do_execveat_common.isra.15+0x687/0x1f80
[   38.621146]        SyS_execve+0x42/0x50
[   38.621725]        do_syscall_64+0x19f/0x480
[   38.622402]        entry_SYSCALL_64_after_swapgs+0x5d/0xdb
[   38.623901] 
-> #1 (&sig->cred_guard_mutex){+.+.+.}:
[   38.629553]        lock_acquire+0x130/0x3e0
[   38.633847]        mutex_lock_killable_nested+0xcc/0x960
[   38.639275]        do_io_accounting+0x1fb/0x7e0
[   38.643919]        proc_tgid_io_accounting+0x22/0x30
[   38.649013]        proc_single_show+0xfd/0x170
[   38.653572]        seq_read+0x4b6/0x12d0
[   38.657626]        __vfs_read+0x115/0x560
[   38.661752]        vfs_read+0x124/0x390
[   38.665706]        SyS_pread64+0x145/0x170
[   38.669920]        do_syscall_64+0x19f/0x480
[   38.674448]        entry_SYSCALL_64_after_swapgs+0x5d/0xdb
[   38.680149] 
-> #0 (&p->lock){+.+.+.}:
[   38.684603]        __lock_acquire+0x3189/0x4a10
[   38.689247]        lock_acquire+0x130/0x3e0
[   38.693615]        mutex_lock_nested+0xc0/0x870
[   38.698267]        seq_read+0xdd/0x12d0
[   38.702225]        proc_reg_read+0xfd/0x180
[   38.706522]        do_loop_readv_writev.part.1+0xd5/0x280
[   38.712063]        do_readv_writev+0x56e/0x7b0
[   38.716636]        vfs_readv+0x84/0xc0
[   38.720498]        default_file_splice_read+0x44b/0x7e0
[   38.725834]        do_splice_to+0x10c/0x170
[   38.730142]        SyS_splice+0x10d2/0x14d0
[   38.734435]        do_syscall_64+0x19f/0x480
[   38.738836]        entry_SYSCALL_64_after_swapgs+0x5d/0xdb
[   38.744432] 
[   38.744432] other info that might help us debug this:
[   38.744432] 
[   38.752552] Chain exists of:
  &p->lock --> &sig->cred_guard_mutex --> &pipe->mutex/1

[   38.761598]  Possible unsafe locking scenario:
[   38.761598] 
[   38.767642]        CPU0                    CPU1
[   38.772285]        ----                    ----
[   38.776923]   lock(&pipe->mutex/1);
[   38.780873]                                lock(&sig->cred_guard_mutex);
[   38.788053]                                lock(&pipe->mutex/1);
[   38.794529]   lock(&p->lock);
[   38.797845] 
[   38.797845]  *** DEADLOCK ***
[   38.797845] 
[   38.803981] 1 lock held by syz-executor842/2060:
[   38.808710]  #0:  (&pipe->mutex/1){+.+.+.}, at: [<ffffffff815044be>] pipe_lock+0x5e/0x70
[   38.817504] 
[   38.817504] stack backtrace:
[   38.821985] CPU: 1 PID: 2060 Comm: syz-executor842 Not tainted 4.9.128+ #41
[   38.829092]  ffff8801ced2f278 ffffffff81af2469 ffffffff83aa1330 ffffffff83aa87a0
[   38.837099]  ffffffff83aa34f0 ffff8801d262e7d0 ffff8801d262df00 ffff8801ced2f2c0
[   38.845187]  ffffffff813e79ed 0000000000000001 00000000d262e7b0 0000000000000001
[   38.853168] Call Trace:
[   38.855732]  [<ffffffff81af2469>] dump_stack+0xc1/0x128
[   38.861190]  [<ffffffff813e79ed>] print_circular_bug.cold.36+0x2f7/0x432
[   38.868013]  [<ffffffff81202779>] __lock_acquire+0x3189/0x4a10
[   38.873962]  [<ffffffff810aaadd>] ? unwind_next_frame+0x7d/0xd0
[   38.880006]  [<ffffffff811ff5f0>] ? trace_hardirqs_on+0x10/0x10
[   38.886121]  [<ffffffff81204b10>] lock_acquire+0x130/0x3e0
[   38.891780]  [<ffffffff8155eafd>] ? seq_read+0xdd/0x12d0
[   38.897211]  [<ffffffff8155eafd>] ? seq_read+0xdd/0x12d0
[   38.902635]  [<ffffffff827826d0>] mutex_lock_nested+0xc0/0x870
[   38.908579]  [<ffffffff8155eafd>] ? seq_read+0xdd/0x12d0
[   38.914200]  [<ffffffff82782610>] ? mutex_trylock+0x3e0/0x3e0
[   38.920059]  [<ffffffff811fefe7>] ? mark_held_locks+0xc7/0x130
[   38.926038]  [<ffffffff8140e050>] ? get_page_from_freelist+0xae0/0x18e0
[   38.932867]  [<ffffffff8155eafd>] seq_read+0xdd/0x12d0
[   38.938251]  [<ffffffff815bced4>] ? fsnotify+0x114/0x1100
[   38.943763]  [<ffffffff8155ea20>] ? seq_lseek+0x3c0/0x3c0
[   38.949282]  [<ffffffff815bcdc0>] ? __fsnotify_inode_delete+0x30/0x30
[   38.955838]  [<ffffffff8163438d>] proc_reg_read+0xfd/0x180
[   38.961432]  [<ffffffff8155ea20>] ? seq_lseek+0x3c0/0x3c0
[   38.966940]  [<ffffffff814ea805>] do_loop_readv_writev.part.1+0xd5/0x280
[   38.973749]  [<ffffffff814ebeae>] do_readv_writev+0x56e/0x7b0
[   38.979606]  [<ffffffff814eb940>] ? vfs_write+0x520/0x520
[   38.985114]  [<ffffffff814d2c35>] ? kasan_unpoison_shadow+0x35/0x50
[   38.991493]  [<ffffffff81b2f6f2>] ? push_pipe+0x3e2/0x770
[   38.997004]  [<ffffffff81b36e5e>] ? iov_iter_get_pages_alloc+0x2be/0xee0
[   39.004046]  [<ffffffff814ec174>] vfs_readv+0x84/0xc0
[   39.009208]  [<ffffffff81588a1b>] default_file_splice_read+0x44b/0x7e0
[   39.015999]  [<ffffffff815885d0>] ? do_splice_direct+0x270/0x270
[   39.022120]  [<ffffffff811ff5f0>] ? trace_hardirqs_on+0x10/0x10
[   39.028151]  [<ffffffff811ff5f0>] ? trace_hardirqs_on+0x10/0x10
[   39.034185]  [<ffffffff815bcdc0>] ? __fsnotify_inode_delete+0x30/0x30
[   39.040766]  [<ffffffff815be1c0>] ? __fsnotify_update_child_dentry_flags.part.0+0x300/0x300
[   39.049483]  [<ffffffff819a3129>] ? avc_policy_seqno+0x9/0x20
[   39.055340]  [<ffffffff819b8272>] ? selinux_file_permission+0x82/0x470
[   39.062020]  [<ffffffff8199a76f>] ? security_file_permission+0x8f/0x1e0
[   39.068749]  [<ffffffff814eaed5>] ? rw_verify_area+0xe5/0x2a0
[   39.074603]  [<ffffffff815885d0>] ? do_splice_direct+0x270/0x270
[   39.080718]  [<ffffffff81587b1c>] do_splice_to+0x10c/0x170
[   39.086311]  [<ffffffff8158d062>] SyS_splice+0x10d2/0x14d0
[   39.092045]  [<ffffffff812976cc>] ? SyS_futex+0x26c/0x370
[   39.097557]  [<ffffffff8158bf90>] ? compat_SyS_vmsplice+0x160/0x160
executing program
[   39.104104]  [<ffffffff810053f8>] ? do_syscall_64+0x48/0x480
[   39.109896]  [<ffffffff8158bf90>] ? compat_SyS_vmsplice+0x160/0x160
[   39.116274]  [<ffffffff8100554f>] do_syscall_64+0x19f/0x480
[   39.121959]  [<ffffffff8278df13>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
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