Warning: Permanently added '10.128.0.89' (ECDSA) to the list of known hosts.
executing program
syzkaller login: [ 38.409306]
[ 38.411005] ======================================================
[ 38.417344] [ INFO: possible circular locking dependency detected ]
[ 38.423784] 4.4.174+ #4 Not tainted
[ 38.427391] -------------------------------------------------------
[ 38.433774] syz-executor366/2077 is trying to acquire lock:
[ 38.439458] (&pipe->mutex/1){+.+.+.}, at: [<ffffffff814b28fd>] fifo_open+0x15d/0xa00
[ 38.448018]
[ 38.448018] but task is already holding lock:
[ 38.454091] (&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff814acb45>] prepare_bprm_creds+0x55/0x120
[ 38.463969]
[ 38.463969] which lock already depends on the new lock.
[ 38.463969]
[ 38.472264]
[ 38.472264] the existing dependency chain (in reverse order) is:
[ 38.479979]
-> #1 (&sig->cred_guard_mutex){+.+.+.}:
[ 38.485694] [<ffffffff81205f6e>] lock_acquire+0x15e/0x450
[ 38.491940] [<ffffffff8270e5a2>] mutex_lock_interruptible_nested+0xd2/0xce0
[ 38.499762] [<ffffffff815e7f78>] proc_pid_attr_write+0x1a8/0x2a0
[ 38.506627] [<ffffffff81496916>] __vfs_write+0x116/0x3d0
[ 38.512797] [<ffffffff81496ce2>] __kernel_write+0x112/0x370
[ 38.519308] [<ffffffff81532e6d>] write_pipe_buf+0x15d/0x1f0
[ 38.525817] [<ffffffff81533b6e>] __splice_from_pipe+0x37e/0x7a0
[ 38.532624] [<ffffffff81536be8>] splice_from_pipe+0x108/0x170
[ 38.539265] [<ffffffff81536cdc>] default_file_splice_write+0x3c/0x80
[ 38.546489] [<ffffffff81537d31>] SyS_splice+0xd71/0x13a0
[ 38.552655] [<ffffffff82718ba1>] entry_SYSCALL_64_fastpath+0x1e/0x9a
[ 38.559862]
-> #0 (&pipe->mutex/1){+.+.+.}:
[ 38.565037] [<ffffffff81202d86>] __lock_acquire+0x37d6/0x4f50
[ 38.571645] [<ffffffff81205f6e>] lock_acquire+0x15e/0x450
[ 38.577902] [<ffffffff8270c191>] mutex_lock_nested+0xc1/0xb80
[ 38.584498] [<ffffffff814b28fd>] fifo_open+0x15d/0xa00
[ 38.590543] [<ffffffff8149154f>] do_dentry_open+0x38f/0xbd0
[ 38.596973] [<ffffffff81494d3b>] vfs_open+0x10b/0x210
[ 38.602877] [<ffffffff814c5ddf>] path_openat+0x136f/0x4470
[ 38.609282] [<ffffffff814ccab1>] do_filp_open+0x1a1/0x270
[ 38.615542] [<ffffffff814a7c8c>] do_open_execat+0x10c/0x6e0
[ 38.621969] [<ffffffff814ad306>] do_execveat_common.isra.0+0x6f6/0x1e90
[ 38.629515] [<ffffffff814af422>] SyS_execve+0x42/0x50
[ 38.635497] [<ffffffff82718ef5>] return_from_execve+0x0/0x23
[ 38.642016]
[ 38.642016] other info that might help us debug this:
[ 38.642016]
[ 38.650173] Possible unsafe locking scenario:
[ 38.650173]
[ 38.656216] CPU0 CPU1
[ 38.660864] ---- ----
[ 38.665508] lock(&sig->cred_guard_mutex);
[ 38.670041] lock(&pipe->mutex/1);
[ 38.676531] lock(&sig->cred_guard_mutex);
[ 38.683579] lock(&pipe->mutex/1);
[ 38.687539]
[ 38.687539] *** DEADLOCK ***
[ 38.687539]
[ 38.693649] 1 lock held by syz-executor366/2077:
[ 38.698522] #0: (&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff814acb45>] prepare_bprm_creds+0x55/0x120
[ 38.708926]
[ 38.708926] stack backtrace:
[ 38.713401] CPU: 0 PID: 2077 Comm: syz-executor366 Not tainted 4.4.174+ #4
[ 38.720438] 0000000000000000 8cdf25ee026bbb30 ffff8800b6fff530 ffffffff81aad1a1
[ 38.728462] ffffffff84057a80 ffff8801d5d8af80 ffffffff83abd100 ffffffff83ab6500
[ 38.736455] ffffffff83abd100 ffff8800b6fff580 ffffffff813abcda ffff8800b6fff660
[ 38.744454] Call Trace:
[ 38.747024] [<ffffffff81aad1a1>] dump_stack+0xc1/0x120
[ 38.752375] [<ffffffff813abcda>] print_circular_bug.cold+0x2f7/0x44e
[ 38.758938] [<ffffffff81202d86>] __lock_acquire+0x37d6/0x4f50
[ 38.764944] [<ffffffff811ff5b0>] ? trace_hardirqs_on+0x10/0x10
[ 38.771128] [<ffffffff814ccab1>] ? do_filp_open+0x1a1/0x270
[ 38.776918] [<ffffffff814ad306>] ? do_execveat_common.isra.0+0x6f6/0x1e90
[ 38.783924] [<ffffffff814af422>] ? SyS_execve+0x42/0x50
[ 38.789354] [<ffffffff82718ef5>] ? stub_execve+0x5/0x5
[ 38.794818] [<ffffffff8123a761>] ? debug_lockdep_rcu_enabled+0x71/0xa0
[ 38.801571] [<ffffffff8123a761>] ? debug_lockdep_rcu_enabled+0x71/0xa0
[ 38.808317] [<ffffffff81205f6e>] lock_acquire+0x15e/0x450
[ 38.813923] [<ffffffff814b28fd>] ? fifo_open+0x15d/0xa00
[ 38.819448] [<ffffffff814b28fd>] ? fifo_open+0x15d/0xa00
[ 38.824982] [<ffffffff8270c191>] mutex_lock_nested+0xc1/0xb80
[ 38.830960] [<ffffffff814b28fd>] ? fifo_open+0x15d/0xa00
[ 38.836485] [<ffffffff8123a761>] ? debug_lockdep_rcu_enabled+0x71/0xa0
[ 38.843262] [<ffffffff8270c0d0>] ? mutex_trylock+0x500/0x500
[ 38.849177] [<ffffffff814b29ed>] ? fifo_open+0x24d/0xa00
[ 38.854723] [<ffffffff814b2a2c>] ? fifo_open+0x28c/0xa00
[ 38.860251] [<ffffffff814b28fd>] fifo_open+0x15d/0xa00
[ 38.865595] [<ffffffff8149154f>] do_dentry_open+0x38f/0xbd0
[ 38.871373] [<ffffffff814b6d8e>] ? __inode_permission2+0x9e/0x250
[ 38.877699] [<ffffffff814b27a0>] ? pipe_release+0x250/0x250
[ 38.883494] [<ffffffff81494d3b>] vfs_open+0x10b/0x210
[ 38.888755] [<ffffffff814c4947>] ? may_open.isra.0+0xe7/0x210
[ 38.894754] [<ffffffff814c5ddf>] path_openat+0x136f/0x4470
[ 38.900457] [<ffffffff81b46d63>] ? depot_save_stack+0x1c3/0x5f0
[ 38.906607] [<ffffffff814c4a70>] ? may_open.isra.0+0x210/0x210
[ 38.912656] [<ffffffff81409597>] ? kmemdup+0x27/0x60
[ 38.917907] [<ffffffff81965573>] ? selinux_cred_prepare+0x43/0xa0
[ 38.924234] [<ffffffff8194f053>] ? security_prepare_creds+0x83/0xc0
[ 38.930724] [<ffffffff8113a098>] ? prepare_creds+0x228/0x2b0
[ 38.936648] [<ffffffff8113b3b2>] ? prepare_exec_creds+0x12/0xf0
[ 38.942792] [<ffffffff814acee6>] ? do_execveat_common.isra.0+0x2d6/0x1e90
[ 38.949790] [<ffffffff82718ef5>] ? stub_execve+0x5/0x5
[ 38.955148] [<ffffffff81484197>] ? kasan_kmalloc+0xb7/0xd0
[ 38.960857] [<ffffffff8148475f>] ? kasan_slab_alloc+0xf/0x20
[ 38.966743] [<ffffffff8147fe9c>] ? kmem_cache_alloc+0xdc/0x2c0
[ 38.972799] [<ffffffff81139e98>] ? prepare_creds+0x28/0x2b0
[ 38.978597] [<ffffffff8113b3b2>] ? prepare_exec_creds+0x12/0xf0
[ 38.984737] [<ffffffff814ccab1>] do_filp_open+0x1a1/0x270
[ 38.990348] [<ffffffff8102e3c6>] ? save_stack_trace+0x26/0x50
[ 38.996304] [<ffffffff814cc910>] ? user_path_mountpoint_at+0x50/0x50
[ 39.002876] [<ffffffff814af422>] ? SyS_execve+0x42/0x50
[ 39.008315] [<ffffffff82718ef5>] ? stub_execve+0x5/0x5
[ 39.013672] [<ffffffff811fffff>] ? __lock_acquire+0xa4f/0x4f50
[ 39.019727] [<ffffffff811ff5b0>] ? trace_hardirqs_on+0x10/0x10
[ 39.025766] [<ffffffff8123a98b>] ? rcu_read_lock_sched_held+0x10b/0x130
[ 39.032596] [<ffffffff814a7c8c>] do_open_execat+0x10c/0x6e0
[ 39.038380] [<ffffffff8123a761>] ? debug_lockdep_rcu_enabled+0x71/0xa0
[ 39.045172] [<ffffffff814a7b80>] ? setup_arg_pages+0x7b0/0x7b0
[ 39.051219] [<ffffffff814ad2c8>] ? do_execveat_common.isra.0+0x6b8/0x1e90
[ 39.058219] [<ffffffff814ad306>] do_execveat_common.isra.0+0x6f6/0x1e90
[ 39.065086] [<ffffffff814ad032>] ? do_execveat_common.isra.0+0x422/0x1e90
[ 39.072095] [<ffffffff8148ad12>] ? __check_object_size+0x222/0x332
[ 39.078529] [<ffffffff81b46400>] ? strncpy_from_user+0xd0/0x230
[ 39.084666] [<ffffffff814acc10>] ? prepare_bprm_creds+0x120/0x120
[ 39.090980] [<ffffffff814ca5d2>] ? getname_flags+0x232/0x550
[ 39.096857] [<ffffffff814af422>] SyS_execve+0x42/0x50
[ 39.102119] [<ffffffff82718ef5>] stub_execve+0x5/0x5
[ 39.107288] [<ffffffff82718cb7>] ? tracesys+0x88/0x8d