[....] Starting enhanced syslogd: rsyslogd[ 13.436956] audit: type=1400 audit(1521173899.678:4): avc: denied { syslog } for pid=3649 comm="rsyslogd" capability=34 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=capability2 permissive=1 [?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. Starting mcstransd: [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.33' (ECDSA) to the list of known hosts. 2018/03/16 04:18:31 parsed 1 programs 2018/03/16 04:18:31 executed programs: 0 syzkaller login: [ 25.154032] IPVS: Creating netns size=2536 id=1 [ 25.171593] [ 25.173270] ====================================================== [ 25.179557] [ INFO: possible circular locking dependency detected ] [ 25.185929] 4.9.87-gd6f2774 #5 Not tainted [ 25.190131] ------------------------------------------------------- [ 25.196504] syz-executor0/3819 is trying to acquire lock: [ 25.202010] (&mm->mmap_sem){++++++}, at: [] __might_fault+0xe4/0x1d0 [ 25.210493] but task is already holding lock: [ 25.215137] (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 25.223528] which lock already depends on the new lock. [ 25.223528] [ 25.230510] [ 25.230510] the existing dependency chain (in reverse order) is: [ 25.238098] -> #1 (ashmem_mutex){+.+.+.}: [ 25.242863] lock_acquire+0x12e/0x410 [ 25.247155] mutex_lock_nested+0xbb/0x870 [ 25.251792] ashmem_mmap+0x53/0x400 [ 25.255911] mmap_region+0x7dd/0xfd0 [ 25.260114] do_mmap+0x57b/0xbe0 [ 25.263974] vm_mmap_pgoff+0x16b/0x1b0 [ 25.268350] SyS_mmap_pgoff+0x33f/0x560 [ 25.272815] do_fast_syscall_32+0x2f5/0x870 [ 25.277630] entry_SYSENTER_compat+0x90/0xa2 [ 25.282526] -> #0 (&mm->mmap_sem){++++++}: [ 25.287369] __lock_acquire+0x2bf9/0x3640 [ 25.292007] lock_acquire+0x12e/0x410 [ 25.296309] __might_fault+0x14a/0x1d0 [ 25.300687] ashmem_ioctl+0x3c0/0xfe0 [ 25.304977] compat_ashmem_ioctl+0x3e/0x50 [ 25.309702] compat_SyS_ioctl+0x15f/0x2050 [ 25.314437] do_fast_syscall_32+0x2f5/0x870 [ 25.319260] entry_SYSENTER_compat+0x90/0xa2 [ 25.324157] [ 25.324157] other info that might help us debug this: [ 25.324157] [ 25.332265] Possible unsafe locking scenario: [ 25.332265] [ 25.338290] CPU0 CPU1 [ 25.342927] ---- ---- [ 25.347571] lock(ashmem_mutex); [ 25.351230] lock(&mm->mmap_sem); [ 25.357488] lock(ashmem_mutex); [ 25.363663] lock(&mm->mmap_sem); [ 25.367411] [ 25.367411] *** DEADLOCK *** [ 25.367411] [ 25.373452] 1 lock held by syz-executor0/3819: [ 25.378001] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 25.386937] [ 25.386937] stack backtrace: [ 25.391411] CPU: 1 PID: 3819 Comm: syz-executor0 Not tainted 4.9.87-gd6f2774 #5 [ 25.398847] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.408179] ffff8801b0c37a38 ffffffff81d95bd9 ffffffff853a4cd0 ffffffff853a4cd0 [ 25.416162] ffffffff853c5490 ffff8801d82ee8d8 ffff8801d82ee000 ffff8801b0c37a80 [ 25.424154] ffffffff81238961 ffff8801d82ee8d8 00000000d82ee8b0 ffff8801d82ee8d8 [ 25.432130] Call Trace: [ 25.434692] [] dump_stack+0xc1/0x128 [ 25.440028] [] print_circular_bug+0x271/0x310 [ 25.446141] [] __lock_acquire+0x2bf9/0x3640 [ 25.452088] [] ? avc_has_extended_perms+0x3fc/0xf10 [ 25.458726] [] ? avc_has_extended_perms+0xe2/0xf10 [ 25.465280] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 25.472276] [] ? mark_held_locks+0xaf/0x100 [ 25.478229] [] ? mutex_lock_nested+0x5e3/0x870 [ 25.484455] [] ? __lock_is_held+0xa1/0xf0 [ 25.490223] [] lock_acquire+0x12e/0x410 [ 25.495818] [] ? __might_fault+0xe4/0x1d0 [ 25.501589] [] __might_fault+0x14a/0x1d0 [ 25.507287] [] ? __might_fault+0xe4/0x1d0 [ 25.513057] [] ashmem_ioctl+0x3c0/0xfe0 [ 25.518660] [] ? selinux_file_ioctl+0x355/0x530 [ 25.524952] [] ? selinux_capable+0x40/0x40 [ 25.530826] [] ? get_name+0x250/0x250 [ 25.536265] [] ? compat_SyS_futex+0x1f9/0x2a0 [ 25.542384] [] compat_ashmem_ioctl+0x3e/0x50 [ 25.548419] [] compat_SyS_ioctl+0x15f/0x2050 [ 25.554461]