[....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.403893] random: sshd: uninitialized urandom read (32 bytes read) [ 20.690917] audit: type=1400 audit(1546744492.611:6): avc: denied { map } for pid=1765 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 [ 20.731639] random: sshd: uninitialized urandom read (32 bytes read) [ 21.207080] random: sshd: uninitialized urandom read (32 bytes read) [ 24.638407] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.115' (ECDSA) to the list of known hosts. [ 30.278369] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 30.367423] audit: type=1400 audit(1546744502.281:7): avc: denied { map } for pid=1783 comm="syz-executor242" path="/root/syz-executor242195828" 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 [ 30.395413] audit: type=1400 audit(1546744502.301:8): avc: denied { map } for pid=1784 comm="syz-executor242" 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 [ 30.421630] [ 30.423293] ====================================================== [ 30.429591] WARNING: possible circular locking dependency detected [ 30.436029] 4.14.91+ #3 Not tainted [ 30.439631] ------------------------------------------------------ [ 30.445921] syz-executor242/1785 is trying to acquire lock: [ 30.451645] (&mm->mmap_sem){++++}, at: [] __do_page_fault+0x871/0xb80 [ 30.459873] [ 30.459873] but task is already holding lock: [ 30.465818] (&sb->s_type->i_mutex_key#10){+.+.}, at: [] generic_file_write_iter+0x99/0x650 [ 30.475856] [ 30.475856] which lock already depends on the new lock. [ 30.475856] [ 30.484154] [ 30.484154] the existing dependency chain (in reverse order) is: [ 30.491761] [ 30.491761] -> #2 (&sb->s_type->i_mutex_key#10){+.+.}: [ 30.498490] [ 30.498490] -> #1 (ashmem_mutex){+.+.}: [ 30.503919] [ 30.503919] -> #0 (&mm->mmap_sem){++++}: [ 30.509436] [ 30.509436] other info that might help us debug this: [ 30.509436] [ 30.517550] Chain exists of: [ 30.517550] &mm->mmap_sem --> ashmem_mutex --> &sb->s_type->i_mutex_key#10 [ 30.517550] [ 30.529159] Possible unsafe locking scenario: [ 30.529159] [ 30.535235] CPU0 CPU1 [ 30.539877] ---- ---- [ 30.544517] lock(&sb->s_type->i_mutex_key#10); [ 30.549254] lock(ashmem_mutex); [ 30.555204] lock(&sb->s_type->i_mutex_key#10); [ 30.562564] lock(&mm->mmap_sem); [ 30.566097] [ 30.566097] *** DEADLOCK *** [ 30.566097] [ 30.572132] 2 locks held by syz-executor242/1785: [ 30.576949] #0: (sb_writers#6){.+.+}, at: [] vfs_write+0x3d8/0x4d0 [ 30.585104] #1: (&sb->s_type->i_mutex_key#10){+.+.}, at: [] generic_file_write_iter+0x99/0x650 [ 30.595679] [ 30.595679] stack backtrace: [ 30.600153] CPU: 0 PID: 1785 Comm: syz-executor242 Not tainted 4.14.91+ #3 [ 30.607140] Call Trace: [ 30.609787] dump_stack+0xb9/0x10e [ 30.613319] print_circular_bug.isra.0.cold+0x2dc/0x425 [ 30.618661] ? __lock_acquire+0x2d83/0x3fa0 [ 30.622960] ? trace_hardirqs_on+0x10/0x10 [ 30.627174] ? trace_hardirqs_on+0x10/0x10 [ 30.631397] ? cmp_ex_search+0x71/0x90 [ 30.635263] ? bsearch+0x87/0xa0 [ 30.638610] ? lock_acquire+0x10f/0x380 [ 30.642561] ? __do_page_fault+0x871/0xb80 [ 30.646772] ? down_read+0x37/0xa0 [ 30.650294] ? __do_page_fault+0x871/0xb80 [ 30.654517] ? __do_page_fault+0x871/0xb80 [ 30.658727] ? mark_held_locks+0xa6/0xf0 [ 30.662762] ? bad_area_access_error+0x340/0x340 [ 30.667498] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 30.672322] ? page_fault+0x22/0x50 [ 30.675931] ? iov_iter_fault_in_readable+0x29c/0x350 [ 30.681102] ? iov_iter_fault_in_readable+0x296/0x350 [ 30.686270] ? iov_iter_init+0x1c0/0x1c0 [ 30.690355] ? generic_perform_write+0x158/0x450 [ 30.695096] ? filemap_page_mkwrite+0x2d0/0x2d0 [ 30.699745] ? current_time+0xb0/0xb0 [ 30.703668] ? lock_acquire+0x10f/0x380 [ 30.707639] ? __generic_file_write_iter+0x32e/0x550 [ 30.712736] ? generic_file_write_iter+0x36f/0x650 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 30.717642] ? iov_iter_init+0xa6/0x1c0 [ 30.721596] ? __vfs_write+0x401/0x5a0 [ 30.725463] ? kernel_read+0x110/0x110 [ 30.729333] ? rcu_lockdep_current_cpu_online+0xed/0x140 [ 30.734764] ? rcu_read_lock_sched_held+0x10a/0x130 [ 30.739759] ? vfs_write+0x17f/0x4d0 [ 30.743648] ? SyS_write+0xc0/0x1a0 [ 30.747256] ? SyS_read+0x1a0/0x1a0 [ 30.750862] ? do_syscall_64+0x43/0x4b0 [ 30.754811] ? 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