[ 22.047512] random: sshd: uninitialized urandom read (32 bytes read, 35 bits of entropy available) [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 25.354908] random: sshd: uninitialized urandom read (32 bytes read, 39 bits of entropy available) [ 25.997681] random: sshd: uninitialized urandom read (32 bytes read, 39 bits of entropy available) [ 26.993000] random: sshd: uninitialized urandom read (32 bytes read, 108 bits of entropy available) [ 27.164078] random: sshd: uninitialized urandom read (32 bytes read, 112 bits of entropy available) Warning: Permanently added '10.128.0.16' (ECDSA) to the list of known hosts. [ 32.598299] random: sshd: uninitialized urandom read (32 bytes read, 119 bits of entropy available) executing program [ 32.690397] [ 32.692038] ====================================================== [ 32.698320] [ INFO: possible circular locking dependency detected ] [ 32.704702] 4.4.120-gd63fdf6 #28 Not tainted [ 32.709074] ------------------------------------------------------- [ 32.715449] syzkaller026568/3793 is trying to acquire lock: [ 32.721128] (&mm->mmap_sem){++++++}, at: [] __might_fault+0xe4/0x1d0 [ 32.729746] [ 32.729746] but task is already holding lock: [ 32.735695] (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x367/0xfa0 [ 32.744226] [ 32.744226] which lock already depends on the new lock. [ 32.744226] [ 32.752511] [ 32.752511] the existing dependency chain (in reverse order) is: [ 32.760109] -> #1 (ashmem_mutex){+.+.+.}: [ 32.764867] [] lock_acquire+0x15e/0x460 [ 32.771104] [] mutex_lock_nested+0xbb/0x850 [ 32.777693] [] ashmem_mmap+0x53/0x400 [ 32.783749] [] mmap_region+0x94f/0x1250 [ 32.789988] [] do_mmap+0x4fd/0x9d0 [ 32.795779] [] vm_mmap_pgoff+0x16e/0x1c0 [ 32.802095] [] SyS_mmap_pgoff+0x33f/0x560 [ 32.808498] [] SyS_mmap+0x16/0x20 [ 32.814213] [] entry_SYSCALL_64_fastpath+0x1c/0x98 [ 32.821408] -> #0 (&mm->mmap_sem){++++++}: [ 32.826279] [] __lock_acquire+0x371f/0x4b50 [ 32.832864] [] lock_acquire+0x15e/0x460 [ 32.839098] [] __might_fault+0x14a/0x1d0 [ 32.845425] [] ashmem_ioctl+0x3b4/0xfa0 [ 32.851666] [] do_vfs_ioctl+0x7aa/0xee0 [ 32.857901] [] SyS_ioctl+0x8f/0xc0 [ 32.863699] [] entry_SYSCALL_64_fastpath+0x1c/0x98 [ 32.870897] [ 32.870897] other info that might help us debug this: [ 32.870897] [ 32.879010] Possible unsafe locking scenario: [ 32.879010] [ 32.885037] CPU0 CPU1 [ 32.889686] ---- ---- [ 32.894320] lock(ashmem_mutex); [ 32.897976] lock(&mm->mmap_sem); [ 32.904239] lock(ashmem_mutex); [ 32.910408] lock(&mm->mmap_sem); [ 32.914147] [ 32.914147] *** DEADLOCK *** [ 32.914147] [ 32.920174] 1 lock held by syzkaller026568/3793: [ 32.924901] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x367/0xfa0 [ 32.933954] [ 32.933954] stack backtrace: [ 32.938419] CPU: 1 PID: 3793 Comm: syzkaller026568 Not tainted 4.4.120-gd63fdf6 #28 [ 32.946179] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.955504] 0000000000000000 b5cbab0221867501 ffff8800b76af9b8 ffffffff81d0408d [ 32.963480] ffffffff851a0010 ffffffff851a0010 ffffffff851bdda0 ffff8800bb9188f8 [ 32.971464] ffff8800bb918000 ffff8800b76afa00 ffffffff81233ba1 ffff8800bb9188f8 [ 32.979441] Call Trace: [ 32.982006] [] dump_stack+0xc1/0x124 [ 32.987343] [] print_circular_bug+0x271/0x310 [ 32.993457] [] __lock_acquire+0x371f/0x4b50 [ 32.999412] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 33.006393] [] ? mark_held_locks+0xaf/0x100 [ 33.012342] [] ? __lock_is_held+0xa1/0xf0 [ 33.018115] [] lock_acquire+0x15e/0x460 [ 33.023721] [] ? __might_fault+0xe4/0x1d0 [ 33.029486] [] __might_fault+0x14a/0x1d0 [ 33.035164] [] ? __might_fault+0xe4/0x1d0 [ 33.040932] [] ashmem_ioctl+0x3b4/0xfa0 [ 33.046525] [] ? mmap_region+0x3f9/0x1250 [ 33.052303] [] ? ashmem_shrink_scan+0x390/0x390 [ 33.058591] [] ? vm_mmap_pgoff+0x180/0x1c0 [ 33.064450] [] ? ashmem_shrink_scan+0x390/0x390 [ 33.070747] [] do_vfs_ioctl+0x7aa/0xee0 [ 33.076338] [] ? ioctl_preallocate+0x1f0/0x1f0 [ 33.082558] [] ? fput+0x20/0x150 [ 33.087545] [] ? SyS_mmap_pgoff+0