[....] Starting file context maintaining daemon: restorecond[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.147666] random: sshd: uninitialized urandom read (32 bytes read, 32 bits of entropy available) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.953127] random: sshd: uninitialized urandom read (32 bytes read, 36 bits of entropy available) [ 21.254869] random: sshd: uninitialized urandom read (32 bytes read, 37 bits of entropy available) [ 22.126450] random: sshd: uninitialized urandom read (32 bytes read, 101 bits of entropy available) [ 22.304419] random: sshd: uninitialized urandom read (32 bytes read, 105 bits of entropy available) Warning: Permanently added '10.128.0.11' (ECDSA) to the list of known hosts. [ 27.695110] random: sshd: uninitialized urandom read (32 bytes read, 113 bits of entropy available) executing program [ 27.794126] [ 27.795798] ====================================================== [ 27.802093] [ INFO: possible circular locking dependency detected ] [ 27.808482] 4.4.113-ge70c132 #34 Not tainted [ 27.812860] ------------------------------------------------------- [ 27.819232] syzkaller100514/3312 is trying to acquire lock: [ 27.824910] (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [] shmem_file_llseek+0xf1/0x240 [ 27.835181] [ 27.835181] but task is already holding lock: [ 27.841121] (ashmem_mutex){+.+.+.}, at: [] ashmem_llseek+0x56/0x1f0 [ 27.849630] [ 27.849630] which lock already depends on the new lock. [ 27.849630] [ 27.857917] [ 27.857917] the existing dependency chain (in reverse order) is: [ 27.865508] -> #2 (ashmem_mutex){+.+.+.}: [ 27.870287] [] lock_acquire+0x15e/0x460 [ 27.876522] [] mutex_lock_nested+0xbb/0x850 [ 27.883107] [] ashmem_mmap+0x53/0x400 [ 27.889167] [] mmap_region+0x94f/0x1250 [ 27.895432] [] do_mmap+0x4fd/0x9d0 [ 27.901241] [] vm_mmap_pgoff+0x16e/0x1c0 [ 27.907562] [] SyS_mmap_pgoff+0x33f/0x560 [ 27.913983] [] SyS_mmap+0x16/0x20 [ 27.919694] [] entry_SYSCALL_64_fastpath+0x1c/0x98 [ 27.926887] -> #1 (&mm->mmap_sem){++++++}: [ 27.931734] [] lock_acquire+0x15e/0x460 [ 27.937969] [] __might_fault+0x14a/0x1d0 [ 27.944288] [] filldir+0x162/0x2d0 [ 27.950271] [] dcache_readdir+0x11e/0x7b0 [ 27.956677] [] iterate_dir+0x1c8/0x420 [ 27.962825] [] SyS_getdents+0x14a/0x270 [ 27.969072] [] entry_SYSCALL_64_fastpath+0x1c/0x98 [ 27.976351] -> #0 (&sb->s_type->i_mutex_key#10){+.+.+.}: [ 27.982538] [] __lock_acquire+0x371f/0x4b50 [ 27.989131] [] lock_acquire+0x15e/0x460 [ 27.995374] [] mutex_lock_nested+0xbb/0x850 [ 28.001965] [] shmem_file_llseek+0xf1/0x240 [ 28.008559] [] vfs_llseek+0xa2/0xd0 [ 28.014450] [] ashmem_llseek+0xe7/0x1f0 [ 28.020683] [] SyS_lseek+0xeb/0x170 [ 28.026572] [] entry_SYSCALL_64_fastpath+0x1c/0x98 [ 28.033763] [ 28.033763] other info that might help us debug this: [ 28.033763] [ 28.041874] Chain exists of: &sb->s_type->i_mutex_key#10 --> &mm->mmap_sem --> ashmem_mutex [ 28.051613] Possible unsafe locking scenario: [ 28.051613] [ 28.057641] CPU0 CPU1 [ 28.062277] ---- ---- [ 28.066914] lock(ashmem_mutex); [ 28.070574] lock(&mm->mmap_sem); [ 28.076854] lock(ashmem_mutex); [ 28.083068] lock(&sb->s_type->i_mutex_key#10); [ 28.088160] [ 28.088160] *** DEADLOCK *** [ 28.088160] [ 28.094189] 1 lock held by syzkaller100514/3312: [ 28.099011] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_llseek+0x56/0x1f0 [ 28.108074] [ 28.108074] stack backtrace: [ 28.112546] CPU: 1 PID: 3312 Comm: syzkaller100514 Not tainted 4.4.113-ge70c132 #34 [ 28.120320] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.129646] 0000000000000000 6dda2dfb751b9936 ffff8801d169fad8 ffffffff81d0278d [ 28.137635] ffffffff851a03b0 ffffffff851a9ef0 ffffffff851be140 ffff8801d1ab6798 [ 28.145611] ffff8801d1ab5f00 ffff8801d169fb20 ffffffff81232b51 ffff8801d1ab6798 [ 28.153599] Call Trace: [ 28.156178] [] dump_stack+0xc1/0x124 [ 28.161532] [] print_circular_bug+0x271/0x310 [ 28.167663] [] __lock_acquire+0x371f/0x4b50 [ 28.173613] [] ? perf_event_mmap+0x93/0x910 [ 28.179565] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 28.186582] [] ? vma_link+0xe4/0x170 [ 28.191921] [] ? __lock_is_held+0xa1/0xf0 [ 28.197691] [] lock_acquire+0x15e/0x460 [ 28.203287] [] ? shmem_file_llseek+0xf1/0x240 [ 28.209415] [] ? shmem_file_llseek+0xf1/0x240 [ 28.215552] [] mutex_lock_nested+0xbb/0x850 [ 28.221501] [] ? shmem_file_llseek+0xf1/0x240 [ 28.227617] [] ? mutex_lock_nested+0x5d4/0x850 [ 28.233820] [] ? __ww_mutex_lock+0x14f0/0x14f0 [ 28.240023] [] ? mutex_lock_nested+0x560/0x850