[ 21.140997] random: sshd: uninitialized urandom read (32 bytes read, 33 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: [ 25.199355] random: sshd: uninitialized urandom read (32 bytes read, 38 bits of entropy available) [ 25.668189] random: sshd: uninitialized urandom read (32 bytes read, 38 bits of entropy available) [ 26.601105] random: sshd: uninitialized urandom read (32 bytes read, 105 bits of entropy available) [ 26.787214] random: sshd: uninitialized urandom read (32 bytes read, 110 bits of entropy available) Warning: Permanently added '10.128.15.196' (ECDSA) to the list of known hosts. [ 32.192086] random: sshd: uninitialized urandom read (32 bytes read, 118 bits of entropy available) executing program [ 32.295776] [ 32.297423] ====================================================== [ 32.303709] [ INFO: possible circular locking dependency detected ] [ 32.310081] 4.4.118-g5f7f76a #24 Not tainted [ 32.314454] ------------------------------------------------------- [ 32.320831] syzkaller815429/3792 is trying to acquire lock: [ 32.326508] (&mm->mmap_sem){++++++}, at: [] __might_fault+0xe4/0x1d0 [ 32.335096] [ 32.335096] but task is already holding lock: [ 32.341033] (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x367/0xfa0 [ 32.349531] [ 32.349531] which lock already depends on the new lock. [ 32.349531] [ 32.357814] [ 32.357814] the existing dependency chain (in reverse order) is: [ 32.365400] -> #1 (ashmem_mutex){+.+.+.}: [ 32.370155] [] lock_acquire+0x15e/0x460 [ 32.376398] [] mutex_lock_nested+0xbb/0x850 [ 32.382976] [] ashmem_mmap+0x53/0x400 [ 32.389034] [] mmap_region+0x94f/0x1250 [ 32.395265] [] do_mmap+0x4fd/0x9d0 [ 32.401057] [] vm_mmap_pgoff+0x16e/0x1c0 [ 32.407373] [] SyS_mmap_pgoff+0x33f/0x560 [ 32.413775] [] SyS_mmap+0x16/0x20 [ 32.419485] [] entry_SYSCALL_64_fastpath+0x1c/0x98 [ 32.426668] -> #0 (&mm->mmap_sem){++++++}: [ 32.431509] [] __lock_acquire+0x371f/0x4b50 [ 32.438084] [] lock_acquire+0x15e/0x460 [ 32.444312] [] __might_fault+0x14a/0x1d0 [ 32.450806] [] ashmem_ioctl+0x3b4/0xfa0 [ 32.457050] [] do_vfs_ioctl+0x7aa/0xee0 [ 32.463279] [] SyS_ioctl+0x8f/0xc0 [ 32.469074] [] entry_SYSCALL_64_fastpath+0x1c/0x98 [ 32.476260] [ 32.476260] other info that might help us debug this: [ 32.476260] [ 32.484367] Possible unsafe locking scenario: [ 32.484367] [ 32.490401] CPU0 CPU1 [ 32.495036] ---- ---- [ 32.499669] lock(ashmem_mutex); [ 32.503321] lock(&mm->mmap_sem); [ 32.509574] lock(ashmem_mutex); [ 32.515741] lock(&mm->mmap_sem); [ 32.519490] [ 32.519490] *** DEADLOCK *** [ 32.519490] [ 32.525515] 1 lock held by syzkaller815429/3792: [ 32.530232] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x367/0xfa0 [ 32.539276] [ 32.539276] stack backtrace: [ 32.543740] CPU: 0 PID: 3792 Comm: syzkaller815429 Not tainted 4.4.118-g5f7f76a #24 [ 32.551509] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.560832] 0000000000000000 a336f7fc926736a2 ffff8800bac079b8 ffffffff81d0402d [ 32.568800] ffffffff851a0010 ffffffff851a0010 ffffffff851be610 ffff8801c508a0f8 [ 32.576774] ffff8801c5089800 ffff8800bac07a00 ffffffff81233ba1 ffff8801c508a0f8 [ 32.584740] Call Trace: [ 32.587297] [] dump_stack+0xc1/0x124 [ 32.592636] [] print_circular_bug+0x271/0x310 [ 32.598748] [] __lock_acquire+0x371f/0x4b50 [ 32.604685] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 32.611667] [] ? mark_held_locks+0xaf/0x100 [ 32.617606] [] ? __lock_is_held+0xa1/0xf0 [ 32.623376] [] lock_acquire+0x15e/0x460 [ 32.628969] [] ? __might_fault+0xe4/0x1d0 [ 32.634734] [] __might_fault+0x14a/0x1d0 [ 32.640413] [] ? __might_fault+0xe4/0x1d0 [ 32.646177] [] ashmem_ioctl+0x3b4/0xfa0 [ 32.651768] [] ? mmap_region+0x3f9/0x1250 [ 32.657534] [] ? ashmem_shrink_scan+0x390/0x390 [ 32.663821] [] ? vm_mmap_pgoff+0x180/0x1c0 [ 32.669696] [] ? ashmem_shrink_scan+0x390/0x390 [ 32.675983] [] do_vfs_ioctl+0x7aa/0xee0 [ 32.681572] [] ? ioctl_preallocate+0x1f0/0x1f0 [ 32.687783] [] ? fput+0x20/0x150 [ 32.692768] [] ? SyS_mmap_pgoff+0