[....] Starting OpenBSD Secure Shell server: sshd[ 11.749652] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 35.670570] random: sshd: uninitialized urandom read (32 bytes read) [ 36.144647] audit: type=1400 audit(1549026142.033:6): avc: denied { map } for pid=1768 comm="bash" path="/bin/bash" dev="sda1" ino=1457 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 [ 36.204620] random: sshd: uninitialized urandom read (32 bytes read) [ 36.697367] random: sshd: uninitialized urandom read (32 bytes read) [ 36.844772] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.9' (ECDSA) to the list of known hosts. [ 42.537117] random: sshd: uninitialized urandom read (32 bytes read) [ 42.638411] audit: type=1400 audit(1549026148.523:7): avc: denied { map } for pid=1786 comm="syz-executor125" path="/root/syz-executor125085709" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 executing program executing program [ 44.657602] audit: type=1400 audit(1549026150.543:8): avc: denied { map } for pid=1935 comm="syz-executor125" path="/dev/ashmem" dev="devtmpfs" ino=5069 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:device_t:s0 tclass=chr_file permissive=1 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 51.944127] [ 51.945803] ====================================================== [ 51.952122] WARNING: possible circular locking dependency detected [ 51.958425] 4.14.96+ #20 Not tainted [ 51.962110] ------------------------------------------------------ [ 51.968415] syz-executor125/2270 is trying to acquire lock: [ 51.974113] (&mm->mmap_sem){++++}, at: [] __do_page_fault+0x871/0xb80 [ 51.982326] [ 51.982326] but task is already holding lock: [ 51.988269] (&sb->s_type->i_mutex_key#10){+.+.}, at: [] generic_file_write_iter+0x99/0x650 [ 51.998306] [ 51.998306] which lock already depends on the new lock. [ 51.998306] [ 52.006596] [ 52.006596] the existing dependency chain (in reverse order) is: [ 52.014204] [ 52.014204] -> #2 (&sb->s_type->i_mutex_key#10){+.+.}: [ 52.020936] [ 52.020936] -> #1 (ashmem_mutex){+.+.}: [ 52.026360] [ 52.026360] -> #0 (&mm->mmap_sem){++++}: [ 52.031872] [ 52.031872] other info that might help us debug this: [ 52.031872] [ 52.040004] Chain exists of: [ 52.040004] &mm->mmap_sem --> ashmem_mutex --> &sb->s_type->i_mutex_key#10 [ 52.040004] [ 52.051533] Possible unsafe locking scenario: [ 52.051533] [ 52.057563] CPU0 CPU1 [ 52.062201] ---- ---- [ 52.066841] lock(&sb->s_type->i_mutex_key#10); [ 52.071585] lock(ashmem_mutex); [ 52.077556] lock(&sb->s_type->i_mutex_key#10); [ 52.084803] lock(&mm->mmap_sem); [ 52.088315] [ 52.088315] *** DEADLOCK *** [ 52.088315] [ 52.094347] 2 locks held by syz-executor125/2270: [ 52.099158] #0: (sb_writers#6){.+.+}, at: [] vfs_write+0x3d8/0x4d0 [ 52.107209] #1: (&sb->s_type->i_mutex_key#10){+.+.}, at: [] generic_file_write_iter+0x99/0x650 [ 52.117681] [ 52.117681] stack backtrace: [ 52.122153] CPU: 1 PID: 2270 Comm: syz-executor125 Not tainted 4.14.96+ #20 [ 52.129221] Call Trace: [ 52.131807] dump_stack+0xb9/0x10e [ 52.135327] print_circular_bug.isra.0.cold+0x2dc/0x425 [ 52.140682] ? __lock_acquire+0x2d83/0x3fa0 [ 52.144977] ? trace_hardirqs_on+0x10/0x10 [ 52.149190] ? trace_hardirqs_on+0x10/0x10 [ 52.153419] ? cmp_ex_search+0x71/0x90 [ 52.157297] ? bsearch+0x87/0xa0 [ 52.160647] ? lock_acquire+0x10f/0x380 [ 52.164597] ? __do_page_fault+0x871/0xb80 [ 52.168807] ? down_read+0x37/0xa0 [ 52.172323] ? __do_page_fault+0x871/0xb80 [ 52.176551] ? __do_page_fault+0x871/0xb80 [ 52.180773] ? mark_held_locks+0xa6/0xf0 [ 52.184809] ? bad_area_access_error+0x340/0x340 [ 52.189539] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 52.194356] ? page_fault+0x22/0x50 [ 52.197960] ? iov_iter_fault_in_readable+0x29c/0x350 [ 52.203123] ? iov_iter_fault_in_readable+0x296/0x350 [ 52.208287] ? iov_iter_init+0x1c0/0x1c0 [ 52.212340] ? generic_perform_write+0x158/0x450 [ 52.217070] ? filemap_page_mkwrite+0x2d0/0x2d0 [ 52.221715] ? current_time+0xb0/0xb0 [ 52.225494] ? lock_acquire+0x10f/0x380 [ 52.229482] ? __generic_file_write_iter+0x32e/0x550 [ 52.234594] ? generic_file_write_iter+0x36f/0x650 [ 52.239499] ? __vfs_write+0x401/0x5a0 executing program [ 52.243366] ? kernel_read+0x110/0x110 [ 52.247233] ? rcu_lockdep_current_cpu_online+0xed/0x140 [ 52.252662] ? rcu_read_lock_sched_held+0x10a/0x130 [ 52.257673] ? vfs_write+0x17f/0x4d0 [ 52.261363] ? SyS_write+0xc0/0x1a0 [ 52.264962] ? SyS_read+0x1a0/0x1a0 [ 52.268579] ? SyS_memfd_create+0x2a0/0x310 [ 52.272889] ? kfree+0xf5/0x310 [ 52.276142] ? do_syscall_64+0x43/0x4b0 [ 52.280095] ? SyS_read+0x1a0/0x1a0 [ 52.283694] ? do_syscall_64+0x19b/0x4b0 [ 52.287732] ? entry_SYSCALL_64_after_hwframe+0x42/0xb7 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program