Starting mcstransd: [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 21.503679] random: sshd: uninitialized urandom read (32 bytes read, 36 bits of entropy available) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 24.749080] random: sshd: uninitialized urandom read (32 bytes read, 41 bits of entropy available) [ 25.075204] random: sshd: uninitialized urandom read (32 bytes read, 41 bits of entropy available) [ 26.042492] random: nonblocking pool is initialized Warning: Permanently added '10.128.0.54' (ECDSA) to the list of known hosts. 2018/03/21 22:43:33 parsed 1 programs 2018/03/21 22:43:33 executed programs: 0 [ 31.964982] IPVS: Creating netns size=2552 id=1 [ 31.995760] [ 31.997402] ====================================================== [ 32.003686] [ INFO: possible circular locking dependency detected ] [ 32.010058] 4.4.120-gd63fdf6 #29 Not tainted [ 32.014434] ------------------------------------------------------- [ 32.020806] syz-executor0/3809 is trying to acquire lock: [ 32.026310] (&mm->mmap_sem){++++++}, at: [] __might_fault+0xe4/0x1d0 [ 32.034913] [ 32.034913] but task is already holding lock: [ 32.040854] (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x367/0xfa0 [ 32.049362] [ 32.049362] which lock already depends on the new lock. [ 32.049362] [ 32.057644] [ 32.057644] the existing dependency chain (in reverse order) is: [ 32.065232] -> #1 (ashmem_mutex){+.+.+.}: [ 32.069984] [] lock_acquire+0x15e/0x460 [ 32.076226] [] mutex_lock_nested+0xbb/0x850 [ 32.082807] [] ashmem_mmap+0x53/0x400 [ 32.088867] [] mmap_region+0x94f/0x1250 [ 32.095096] [] do_mmap+0x4fd/0x9d0 [ 32.100892] [] vm_mmap_pgoff+0x16e/0x1c0 [ 32.107208] [] SyS_mmap_pgoff+0x33f/0x560 [ 32.113612] [] do_fast_syscall_32+0x321/0x8a0 [ 32.120370] [] sysenter_flags_fixed+0xd/0x17 [ 32.127033] -> #0 (&mm->mmap_sem){++++++}: [ 32.131879] [] __lock_acquire+0x371f/0x4b50 [ 32.138455] [] lock_acquire+0x15e/0x460 [ 32.144687] [] __might_fault+0x14a/0x1d0 [ 32.151002] [] ashmem_ioctl+0x3b4/0xfa0 [ 32.157230] [] compat_ashmem_ioctl+0x3e/0x50 [ 32.163894] [] compat_SyS_ioctl+0x28a/0x2540 [ 32.170558] [] do_fast_syscall_32+0x321/0x8a0 [ 32.177318] [] sysenter_flags_fixed+0xd/0x17 [ 32.183984] [ 32.183984] other info that might help us debug this: [ 32.183984] [ 32.192101] Possible unsafe locking scenario: [ 32.192101] [ 32.198154] CPU0 CPU1 [ 32.202787] ---- ---- [ 32.207421] lock(ashmem_mutex); [ 32.211074] lock(&mm->mmap_sem); [ 32.217329] lock(ashmem_mutex); [ 32.223517] lock(&mm->mmap_sem); [ 32.227251] [ 32.227251] *** DEADLOCK *** [ 32.227251] [ 32.233279] 1 lock held by syz-executor0/3809: [ 32.237832] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x367/0xfa0 [ 32.246884] [ 32.246884] stack backtrace: [ 32.251352] CPU: 0 PID: 3809 Comm: syz-executor0 Not tainted 4.4.120-gd63fdf6 #29 [ 32.258937] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 32.268257] 0000000000000000 c635996826bac0c2 ffff8800a9e8f8a8 ffffffff81d0408d [ 32.276232] ffffffff8519fe60 ffffffff8519fe60 ffffffff851bf030 ffff8801c4c950f8 [ 32.284203] ffff8801c4c94800 ffff8800a9e8f8f0 ffffffff81233ba1 ffff8801c4c950f8 [ 32.292167] Call Trace: [ 32.294725] [] dump_stack+0xc1/0x124 [ 32.300060] [] print_circular_bug+0x271/0x310 [ 32.306175] [] __lock_acquire+0x371f/0x4b50 [ 32.312130] [] ? avc_has_extended_perms+0xe2/0xf30 [ 32.318679] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 32.325661] [] ? mark_held_locks+0xaf/0x100 [ 32.331603] [] ? __lock_is_held+0xa1/0xf0 [ 32.337373] [] lock_acquire+0x15e/0x460 [ 32.342965] [] ? __might_fault+0xe4/0x1d0 [ 32.348732] [] __might_fault+0x14a/0x1d0 [ 32.354410] [] ? __might_fault+0xe4/0x1d0 [ 32.360178] [] ashmem_ioctl+0x3b4/0xfa0 [ 32.365769] [] ? selinux_file_ioctl+0x363/0x570 [ 32.372057] [] ? selinux_capable+0x30/0x30 [ 32.377930] [] ? ashmem_shrink_scan+0x390/0x390 [ 32.384221] [] ? vma_set_page_prot+0x10b/0x150 [ 32.390443] [] ? exit_robust_list+0x240/0x240 [ 32.396564] [] compat_ashmem_ioctl+0x3e/0x50 [ 32.402592] [] compat_SyS_ioctl+0x28a/0x2540 [ 32.408620] [] ? vm_mmap_pgoff+0x180/0x1c0 [ 32.414472] [] ? ashmem_ioctl+0xfa0/0xfa0 [ 32.420249] [] ? compat_SyS_ppoll+0x420/0x420 [ 32.426361] [] ? vm_mmap_pgoff+0xdf/0x1c0 [ 32.432129] [] ? compat_SyS_futex+0x1f9/0x2a0 [ 32.438241] [] ? compat_SyS_get_robust_list+0x300/0x300 [ 32.445232] [