[....] Starting file context maintaining daemon: restorecond[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting O[ 16.703959] random: sshd: uninitialized urandom read (32 bytes read, 33 bits of entropy available) penBSD Secure Shell server: sshd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.158794] random: sshd: uninitialized urandom read (32 bytes read, 39 bits of entropy available) [ 21.679370] random: sshd: uninitialized urandom read (32 bytes read, 40 bits of entropy available) [ 22.635324] random: sshd: uninitialized urandom read (32 bytes read, 117 bits of entropy available) [ 22.805400] random: sshd: uninitialized urandom read (32 bytes read, 121 bits of entropy available) Warning: Permanently added '10.128.15.245' (ECDSA) to the list of known hosts. [ 28.172499] random: nonblocking pool is initialized executing program [ 28.276488] [ 28.278147] ====================================================== [ 28.284438] [ INFO: possible circular locking dependency detected ] [ 28.290810] 4.4.112-g3fc4284 #32 Not tainted [ 28.295190] ------------------------------------------------------- [ 28.301566] syzkaller274914/3322 is trying to acquire lock: [ 28.307243] (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [] shmem_file_llseek+0xf1/0x240 [ 28.317510] [ 28.317510] but task is already holding lock: [ 28.323463] (ashmem_mutex){+.+.+.}, at: [] ashmem_llseek+0x56/0x1f0 [ 28.331968] [ 28.331968] which lock already depends on the new lock. [ 28.331968] [ 28.340253] [ 28.340253] the existing dependency chain (in reverse order) is: [ 28.347929] -> #2 (ashmem_mutex){+.+.+.}: [ 28.352688] [] lock_acquire+0x15e/0x460 [ 28.358931] [] mutex_lock_nested+0xbb/0x850 [ 28.365514] [] ashmem_mmap+0x53/0x400 [ 28.371576] [] mmap_region+0x94f/0x1250 [ 28.377812] [] do_mmap+0x4fd/0x9d0 [ 28.383609] [] vm_mmap_pgoff+0x16e/0x1c0 [ 28.389928] [] SyS_mmap_pgoff+0x33f/0x560 [ 28.396348] [] SyS_mmap+0x16/0x20 [ 28.402061] [] entry_SYSCALL_64_fastpath+0x16/0x92 [ 28.409252] -> #1 (&mm->mmap_sem){++++++}: [ 28.414091] [] lock_acquire+0x15e/0x460 [ 28.420324] [] __might_fault+0x14a/0x1d0 [ 28.426656] [] filldir+0x162/0x2d0 [ 28.432455] [] dcache_readdir+0x11e/0x7b0 [ 28.438862] [] iterate_dir+0x1c8/0x420 [ 28.445008] [] SyS_getdents+0x14a/0x270 [ 28.451236] [] entry_SYSCALL_64_fastpath+0x16/0x92 [ 28.458425] -> #0 (&sb->s_type->i_mutex_key#10){+.+.+.}: [ 28.464614] [] __lock_acquire+0x371f/0x4b50 [ 28.471192] [] lock_acquire+0x15e/0x460 [ 28.477420] [] mutex_lock_nested+0xbb/0x850 [ 28.484005] [] shmem_file_llseek+0xf1/0x240 [ 28.490580] [] vfs_llseek+0xa2/0xd0 [ 28.496465] [] ashmem_llseek+0xe7/0x1f0 [ 28.502694] [] SyS_lseek+0xeb/0x170 [ 28.508574] [] entry_SYSCALL_64_fastpath+0x16/0x92 [ 28.515776] [ 28.515776] other info that might help us debug this: [ 28.515776] [ 28.523888] Chain exists of: &sb->s_type->i_mutex_key#10 --> &mm->mmap_sem --> ashmem_mutex [ 28.533606] Possible unsafe locking scenario: [ 28.533606] [ 28.539630] CPU0 CPU1 [ 28.544266] ---- ---- [ 28.548920] lock(ashmem_mutex); [ 28.552575] lock(&mm->mmap_sem); [ 28.558832] lock(ashmem_mutex); [ 28.565010] lock(&sb->s_type->i_mutex_key#10); [ 28.570086] [ 28.570086] *** DEADLOCK *** [ 28.570086] [ 28.576126] 1 lock held by syzkaller274914/3322: [ 28.580848] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_llseek+0x56/0x1f0 [ 28.589892] [ 28.589892] stack backtrace: [ 28.594365] CPU: 1 PID: 3322 Comm: syzkaller274914 Not tainted 4.4.112-g3fc4284 #32 [ 28.602127] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.611454] 0000000000000000 018b6d96822d437d ffff8801d091fad8 ffffffff81d054ed [ 28.619435] ffffffff8519e370 ffffffff851a8060 ffffffff851bc970 ffff8801d0d90898 [ 28.627418] ffff8801d0d90000 ffff8801d091fb20 ffffffff81232b91 ffff8801d0d90898 [ 28.635387] Call Trace: [ 28.637948] [] dump_stack+0xc1/0x124 [ 28.643282] [] print_circular_bug+0x271/0x310 [ 28.649398] [] __lock_acquire+0x371f/0x4b50 [ 28.655357] [] ? perf_event_mmap+0x93/0x910 [ 28.661303] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 28.668299] [] ? vma_link+0xe4/0x170 [ 28.673632] [] ? __lock_is_held+0xa1/0xf0 [ 28.679399] [] lock_acquire+0x15e/0x460 [ 28.684990] [] ? shmem_file_llseek+0xf1/0x240 [ 28.691101] [] ? shmem_file_llseek+0xf1/0x240 [ 28.697216] [] mutex_lock_nested+0xbb/0x850 [ 28.703156] [] ? shmem_file_llseek+0xf1/0x240 [ 28.709283] [] ? mutex_lock_nested+0x5d4/0x850 [ 28.715484] [] ? __ww_mutex_lock+0x14f0/0x14f0 [ 28.721685] [] ? mutex_lock_nested+0x560/0x850 [ 28.