[....] Starting OpenBSD Secure Shell server: sshd[ 10.317608] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 30.835682] random: sshd: uninitialized urandom read (32 bytes read) [ 31.100942] audit: type=1400 audit(1545407109.499:6): avc: denied { map } for pid=1779 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 [ 31.143626] random: sshd: uninitialized urandom read (32 bytes read) [ 31.592575] random: sshd: uninitialized urandom read (32 bytes read) [ 52.478930] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.6' (ECDSA) to the list of known hosts. [ 58.144215] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 58.239954] audit: type=1400 audit(1545407136.629:7): avc: denied { map } for pid=1803 comm="syz-executor383" path="/root/syz-executor383919513" dev="sda1" ino=16461 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 [ 58.272860] audit: type=1400 audit(1545407136.669:8): avc: denied { map } for pid=1804 comm="syz-executor383" path="/dev/ashmem" dev="devtmpfs" ino=5416 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 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 70.622426] [ 70.624097] ====================================================== [ 70.630389] WARNING: possible circular locking dependency detected [ 70.636681] 4.14.90+ #29 Not tainted [ 70.640367] ------------------------------------------------------ [ 70.646670] syz-executor383/2408 is trying to acquire lock: [ 70.652390] (&mm->mmap_sem){++++}, at: [] __do_page_fault+0x868/0xb60 [ 70.660633] [ 70.660633] but task is already holding lock: [ 70.666595] (&sb->s_type->i_mutex_key#10){+.+.}, at: [] generic_file_write_iter+0x99/0x650 [ 70.676642] [ 70.676642] which lock already depends on the new lock. [ 70.676642] [ 70.684932] [ 70.684932] the existing dependency chain (in reverse order) is: [ 70.692523] [ 70.692523] -> #2 (&sb->s_type->i_mutex_key#10){+.+.}: [ 70.699259] down_write+0x34/0x90 [ 70.703210] shmem_fallocate+0x149/0xb20 [ 70.707767] ashmem_shrink_scan+0x1b6/0x4e0 [ 70.712586] ashmem_ioctl+0x2cc/0xe20 [ 70.716888] do_vfs_ioctl+0x1a0/0x1030 [ 70.721274] SyS_ioctl+0x7e/0xb0 [ 70.725136] do_syscall_64+0x19b/0x4b0 [ 70.729521] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 70.735224] [ 70.735224] -> #1 (ashmem_mutex){+.+.}: [ 70.740658] __mutex_lock+0xf5/0x1480 [ 70.744955] ashmem_mmap+0x4c/0x430 [ 70.749089] mmap_region+0x836/0xfb0 [ 70.753300] do_mmap+0x551/0xb80 [ 70.757162] vm_mmap_pgoff+0x180/0x1d0 [ 70.761545] SyS_mmap_pgoff+0xf8/0x1a0 [ 70.765933] do_syscall_64+0x19b/0x4b0 [ 70.770316] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 70.776026] [ 70.776026] -> #0 (&mm->mmap_sem){++++}: [ 70.781546] lock_acquire+0x10f/0x380 [ 70.785842] down_read+0x37/0xa0 [ 70.789707] __do_page_fault+0x868/0xb60 [ 70.794265] page_fault+0x22/0x50 [ 70.798222] iov_iter_fault_in_readable+0x2b9/0x370 [ 70.803735] generic_perform_write+0x166/0x430 [ 70.808811] __generic_file_write_iter+0x345/0x540 [ 70.814244] generic_file_write_iter+0x36f/0x650 [ 70.819509] __vfs_write+0x417/0x5c0 [ 70.823735] vfs_write+0x17f/0x4d0 [ 70.827768] SyS_write+0xc2/0x1a0 [ 70.831716] do_syscall_64+0x19b/0x4b0 [ 70.836131] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 70.841827] [ 70.841827] other info that might help us debug this: [ 70.841827] [ 70.849944] Chain exists of: [ 70.849944] &mm->mmap_sem --> ashmem_mutex --> &sb->s_type->i_mutex_key#10 [ 70.849944] [ 70.861450] Possible unsafe locking scenario: [ 70.861450] [ 70.867479] CPU0 CPU1 [ 70.872120] ---- ---- [ 70.876760] lock(&sb->s_type->i_mutex_key#10); [ 70.881490] lock(ashmem_mutex); [ 70.887439] lock(&sb->s_type->i_mutex_key#10); [ 70.894719] lock(&mm->mmap_sem); [ 70.898245] [ 70.898245] *** DEADLOCK *** [ 70.898245] [ 70.904276] 2 locks held by syz-executor383/2408: [ 70.909121] #0: (sb_writers#6){.+.+}, at: [] vfs_write+0x3d7/0x4d0 [ 70.917173] #1: (&sb->s_type->i_mutex_key#10){+.+.}, at: [] generic_file_write_iter+0x99/0x650 [ 70.927641] [ 70.927641] stack backtrace: [ 70.932112] CPU: 0 PID: 2408 Comm: syz-executor383 Not tainted 4.14.90+ #29 [ 70.939181] Call Trace: [ 70.941747] dump_stack+0xb9/0x11b [ 70.945265] print_circular_bug.isra.18.cold.43+0x2d3/0x40c [ 70.950954] ? save_trace+0xd6/0x250 [ 70.954665] __lock_acquire+0x2ff9/0x4320 [ 70.958789] ? mark_held_locks+0xc2/0x130 [ 70.962912] ? finish_task_switch+0x1bd/0x610 [ 70.967387] ? trace_hardirqs_on+0x10/0x10 [ 70.971598] ? __schedule+0x731/0x1ed0 [ 70.975461] ? retint_kernel+0x2d/0x2d [ 70.979334] ? cmp_ex_search+0x6f/0x90 [ 70.983291] ? bsearch+0x83/0xa0 [ 70.986636] lock_acquire+0x10f/0x380 [ 70.990414] ? __do_page_fault+0x868/0xb60 [ 70.994626] down_read+0x37/0xa0 [ 70.997968] ? __do_page_fault+0x868/0xb60 [ 71.002180] __do_page_fault+0x868/0xb60 [ 71.006219] ? bad_area_access_error+0x330/0x330 [ 71.010950] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 71.015766] page_fault+0x22/0x50 [ 71.019195] RIP: 0010:iov_iter_fault_in_readable+0x2b9/0x370 [ 71.024966] RSP: 0018:ffff8881ca32f9f8 EFLAGS: 00010297 [ 71.030306] RAX: 0000000000000000 RBX: 000000000000007f RCX: 0000000000001000 [ 71.037550] RDX: 0000000000000000 RSI: 0000000000001000 RDI: ffff8881ca32fcf8 [ 71.044813] RBP: 1ffff11039465f40 R08: 0000000000001000 R09: ffffea0007449640 [ 71.052064] R10: ffffffff856814a0 R11: ffff8881d1259fff R12: 0000000000000000 [ 71.059324] R13: 0000000020cfa23f R14: 0000000000001000 R15: ffff8881ca32fcf0 [ 71.066598] ? shmem_put_link+0xd0/0xd0 [ 71.070558] ? iov_iter_fault_in_readable+0x2b3/0x370 [ 71.075731] ? flex_array_free_parts+0xd0/0xd0 [ 71.080289] ? __set_page_dirty_no_writeback+0xa7/0x100 [ 71.085640] ? iov_iter_advance+0x1cf/0xc20 [ 71.089941] generic_perform_write+0x166/0x430 [ 71.094508] ? filemap_page_mkwrite+0x2d0/0x2d0 [ 71.099158] ? file_update_time+0xbc/0x390 [ 71.103385] ? current_time+0xb0/0xb0 [ 71.107159] ? lock_acquire+0x10f/0x380 [ 71.111107] __generic_file_write_iter+0x345/0x540 [ 71.116037] generic_file_write_iter+0x36f/0x650 [ 71.120770] ? iov_iter_init+0xa8/0x1c0 [ 71.124721] __vfs_write+0x417/0x5c0 [ 71.128423] ? kernel_read+0x110/0x110 [ 71.132985] ? rcu_read_lock_sched_held+0x102/0x120 [ 71.137978] vfs_write+0x17f/0x4d0 [ 71.141493] SyS_write+0xc2/0x1a0 [ 71.144939] ? SyS_read+0x1a0/0x1a0 [ 71.148557] ? do_syscall_64+0x43/0x4b0 [ 71.152504] ? SyS_read+0x1a0/0x1a0 [ 71.156107] do_syscall_64+0x19b/0x4b0 [ 71.159990] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 71.165175] RIP: 0033:0x446369 executing program executing program [ 71.168359] RSP: 002b:00007fe1f7ad2da8 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 [ 71.176038] RAX: ffffffffffffffda RBX: 00000000006dbc28 RCX: 0000000000446369 [ 71.183290] RDX: 00000000fffffe48 RSI: 0000000020004240 RDI: 0000000000000003 [ 71.190535] RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000 [ 71.197781] R10: 0000000000000000 R11: 0000000000000293 R12: 00000000006dbc2c [ 71.205026] R13: 5f7869736f70275b R14: 6873612f7665642f R15: 00000000006dbd2c executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program