Warning: Permanently added '10.128.0.137' (ECDSA) to the list of known hosts. executing program [ 38.585159] [ 38.586834] ====================================================== [ 38.593157] [ INFO: possible circular locking dependency detected ] [ 38.599535] 4.4.174+ #17 Not tainted [ 38.603228] ------------------------------------------------------- [ 38.609615] syz-executor149/2079 is trying to acquire lock: [ 38.615337] (&pipe->mutex/1){+.+.+.}, at: [] fifo_open+0x15d/0xa00 [ 38.623900] [ 38.623900] but task is already holding lock: [ 38.629845] (&sig->cred_guard_mutex){+.+.+.}, at: [] prepare_bprm_creds+0x55/0x120 [ 38.639772] [ 38.639772] which lock already depends on the new lock. [ 38.639772] [ 38.648077] [ 38.648077] the existing dependency chain (in reverse order) is: [ 38.655681] -> #1 (&sig->cred_guard_mutex){+.+.+.}: [ 38.661388] [] lock_acquire+0x15e/0x450 [ 38.667715] [] mutex_lock_interruptible_nested+0xd2/0xce0 [ 38.675548] [] proc_pid_attr_write+0x1a8/0x2a0 [ 38.682413] [] __vfs_write+0x116/0x3d0 [ 38.688635] [] __kernel_write+0x112/0x370 [ 38.695052] [] write_pipe_buf+0x15d/0x1f0 [ 38.701592] [] __splice_from_pipe+0x37e/0x7a0 [ 38.708362] [] splice_from_pipe+0x108/0x170 [ 38.714966] [] default_file_splice_write+0x3c/0x80 [ 38.722183] [] SyS_splice+0xd71/0x13a0 [ 38.728355] [] do_fast_syscall_32+0x32d/0xa90 [ 38.735132] [] sysenter_flags_fixed+0xd/0x1a [ 38.741814] -> #0 (&pipe->mutex/1){+.+.+.}: [ 38.746892] [] __lock_acquire+0x37d6/0x4f50 [ 38.753479] [] lock_acquire+0x15e/0x450 [ 38.759786] [] mutex_lock_nested+0xc1/0xb80 [ 38.766379] [] fifo_open+0x15d/0xa00 [ 38.772363] [] do_dentry_open+0x38f/0xbd0 [ 38.778778] [] vfs_open+0x10b/0x210 [ 38.784667] [] path_openat+0x136f/0x4470 [ 38.790994] [] do_filp_open+0x1a1/0x270 [ 38.797287] [] do_open_execat+0x10c/0x6e0 [ 38.803761] [] do_execveat_common.isra.0+0x6f6/0x1e90 [ 38.811348] [] compat_SyS_execve+0x48/0x60 [ 38.817855] [] do_fast_syscall_32+0x32d/0xa90 [ 38.824648] [] sysenter_flags_fixed+0xd/0x1a [ 38.831333] [ 38.831333] other info that might help us debug this: [ 38.831333] [ 38.839496] Possible unsafe locking scenario: [ 38.839496] [ 38.845535] CPU0 CPU1 [ 38.850176] ---- ---- [ 38.854928] lock(&sig->cred_guard_mutex); [ 38.859585] lock(&pipe->mutex/1); [ 38.866126] lock(&sig->cred_guard_mutex); [ 38.873230] lock(&pipe->mutex/1); [ 38.877207] [ 38.877207] *** DEADLOCK *** [ 38.877207] [ 38.883241] 1 lock held by syz-executor149/2079: [ 38.887972] #0: (&sig->cred_guard_mutex){+.+.+.}, at: [] prepare_bprm_creds+0x55/0x120 [ 38.898446] [ 38.898446] stack backtrace: [ 38.902925] CPU: 1 PID: 2079 Comm: syz-executor149 Not tainted 4.4.174+ #17 [ 38.909997] 0000000000000000 ced614b29b890d80 ffff8800b648f4c0 ffffffff81aad1a1 [ 38.917991] ffffffff84057a80 ffff8801d5e497c0 ffffffff83abd610 ffffffff83ab6500 [ 38.925986] ffffffff83abd610 ffff8800b648f510 ffffffff813abcda ffff8800b648f5f0 [ 38.933982] Call Trace: [ 38.936546] [] dump_stack+0xc1/0x120 [ 38.941891] [] print_circular_bug.cold+0x2f7/0x44e [ 38.948454] [] __lock_acquire+0x37d6/0x4f50 [ 38.954406] [] ? trace_hardirqs_on+0x10/0x10 [ 38.960459] [] ? do_filp_open+0x1a1/0x270 [ 38.966235] [] ? do_execveat_common.isra.0+0x6f6/0x1e90 [ 38.973223] [] ? compat_SyS_execve+0x48/0x60 [ 38.979303] [] ? do_fast_syscall_32+0x32d/0xa90 [ 38.985606] [] ? sysenter_flags_fixed+0xd/0x1a [ 38.991816] [] ? debug_lockdep_rcu_enabled+0x71/0xa0 [ 38.998544] [] ? debug_lockdep_rcu_enabled+0x71/0xa0 [ 39.005279] [] lock_acquire+0x15e/0x450 [ 39.010884] [] ? fifo_open+0x15d/0xa00 [ 39.016442] [] ? fifo_open+0x15d/0xa00 [ 39.021959] [] mutex_lock_nested+0xc1/0xb80 [ 39.027911] [] ? fifo_open+0x15d/0xa00 [ 39.033431] [] ? debug_lockdep_rcu_enabled+0x71/0xa0 [ 39.040166] [] ? mutex_trylock+0x500/0x500 [ 39.046028] [] ? fifo_open+0x24d/0xa00 [ 39.051539] [] ? fifo_open+0x28c/0xa00 [ 39.057052] [] fifo_open+0x15d/0xa00 [ 39.062396] [] do_dentry_open+0x38f/0xbd0 [ 39.068173] [] ? __inode_permission2+0x9e/0x250 [ 39.074555] [] ? pipe_release+0x250/0x250 [ 39.080340] [] vfs_open+0x10b/0x210 [ 39.085600] [] ? may_open.isra.0+0xe7/0x210 [ 39.091554] [] path_openat+0x136f/0x4470 [ 39.097249] [] ? depot_save_stack+0x1c3/0x5f0 [ 39.103373] [] ? may_open.isra.0+0x210/0x210 [ 39.109409] [] ? kmemdup+0x27/0x60 [ 39.114613] [] ? selinux_cred_prepare+0x43/0xa0 [ 39.120979] [] ? security_prepare_creds+0x83/0xc0 [ 39.127453] [] ? prepare_creds+0x228/0x2b0 [ 39.133316] [] ? prepare_exec_creds+0x12/0xf0 [ 39.139458] [] ? do_execveat_common.isra.0+0x2d6/0x1e90 [ 39.146455] [] ? do_fast_syscall_32+0x32d/0xa90 [ 39.152761] [] ? kasan_kmalloc+0xb7/0xd0 [ 39.158452] [] ? kasan_slab_alloc+0xf/0x20 [ 39.164319] [] ? kmem_cache_alloc+0xdc/0x2c0 [ 39.170354] [] ? prepare_creds+0x28/0x2b0 [ 39.176125] [] ? prepare_exec_creds+0x12/0xf0 [ 39.182299] [] do_filp_open+0x1a1/0x270 [ 39.187912] [] ? save_stack_trace+0x26/0x50 [ 39.193861] [] ? user_path_mountpoint_at+0x50/0x50 [ 39.200423] [] ? compat_SyS_execve+0x48/0x60 [ 39.206463] [] ? do_fast_syscall_32+0x32d/0xa90 [ 39.212758] [] ? sysenter_flags_fixed+0xd/0x1a [ 39.218968] [] ? __lock_acquire+0xa4f/0x4f50 [ 39.225000] [] ? trace_hardirqs_on+0x10/0x10 [ 39.231144] [] ? rcu_read_lock_sched_held+0x10b/0x130 [ 39.237966] [] do_open_execat+0x10c/0x6e0 [ 39.243741] [] ? debug_lockdep_rcu_enabled+0x71/0xa0 [ 39.250467] [] ? setup_arg_pages+0x7b0/0x7b0 [ 39.256531] [] ? do_execveat_common.isra.0+0x6b8/0x1e90 [ 39.263558] [] do_execveat_common.isra.0+0x6f6/0x1e90 [ 39.270376] [] ? do_execveat_common.isra.0+0x422/0x1e90 [ 39.277368] [] ? __check_object_size+0x222/0x332 [ 39.283751] [] ? strncpy_from_user+0xd1/0x230 [ 39.289869] [] ? prepare_bprm_creds+0x120/0x120 [ 39.296161] [] ? getname_flags+0x232/0x550 [ 39.302021] [] compat_SyS_execve+0x48/0x60 [ 39.307880] [] ? SyS_execveat+0x70/0x70 [ 39.313484] [] do_fast_syscall_32+0x32d/0xa90 [ 39.319604] [] sysenter_flags_fixed+0xd/0x1a