[....] Starting enhanced syslogd: rsyslogd[ 12.837205] audit: type=1400 audit(1521303670.836:4): avc: denied { syslog } for pid=3653 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 '10.128.10.18' (ECDSA) to the list of known hosts. 2018/03/17 16:21:18 parsed 1 programs 2018/03/17 16:21:18 executed programs: 0 syzkaller login: [ 20.806275] IPVS: Creating netns size=2536 id=1 [ 20.823520] [ 20.825158] ====================================================== [ 20.831441] [ INFO: possible circular locking dependency detected ] [ 20.837817] 4.9.87-gfc8bd0f #6 Not tainted [ 20.842015] ------------------------------------------------------- [ 20.848388] syz-executor0/3816 is trying to acquire lock: [ 20.853895] (&mm->mmap_sem){++++++}, at: [] __might_fault+0xe4/0x1d0 [ 20.862363] but task is already holding lock: [ 20.866994] (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 20.875378] which lock already depends on the new lock. [ 20.875378] [ 20.882403] [ 20.882403] the existing dependency chain (in reverse order) is: [ 20.889993] -> #1 (ashmem_mutex){+.+.+.}: [ 20.894763] lock_acquire+0x12e/0x410 [ 20.899059] mutex_lock_nested+0xbb/0x870 [ 20.903697] ashmem_mmap+0x53/0x400 [ 20.907814] mmap_region+0x7dd/0xfd0 [ 20.912019] do_mmap+0x57b/0xbe0 [ 20.915874] vm_mmap_pgoff+0x16b/0x1b0 [ 20.920250] SyS_mmap_pgoff+0x33f/0x560 [ 20.924714] do_fast_syscall_32+0x2f5/0x870 [ 20.929526] entry_SYSENTER_compat+0x90/0xa2 [ 20.934420] -> #0 (&mm->mmap_sem){++++++}: [ 20.939274] __lock_acquire+0x2bf9/0x3640 [ 20.943911] lock_acquire+0x12e/0x410 [ 20.948201] __might_fault+0x14a/0x1d0 [ 20.952578] ashmem_ioctl+0x3c0/0xfe0 [ 20.956878] compat_ashmem_ioctl+0x3e/0x50 [ 20.961610] compat_SyS_ioctl+0x15f/0x2050 [ 20.966335] do_fast_syscall_32+0x2f5/0x870 [ 20.971146] entry_SYSENTER_compat+0x90/0xa2 [ 20.976043] [ 20.976043] other info that might help us debug this: [ 20.976043] [ 20.984151] Possible unsafe locking scenario: [ 20.984151] [ 20.990172] CPU0 CPU1 [ 20.994808] ---- ---- [ 20.999448] lock(ashmem_mutex); [ 21.003099] lock(&mm->mmap_sem); [ 21.009352] lock(ashmem_mutex); [ 21.015518] lock(&mm->mmap_sem); [ 21.019255] [ 21.019255] *** DEADLOCK *** [ 21.019255] [ 21.025283] 1 lock held by syz-executor0/3816: [ 21.029831] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 21.038760] [ 21.038760] stack backtrace: [ 21.043228] CPU: 1 PID: 3816 Comm: syz-executor0 Not tainted 4.9.87-gfc8bd0f #6 [ 21.050641] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.059966] ffff8801d7db7a38 ffffffff81d95bd9 ffffffff853a4cd0 ffffffff853a4cd0 [ 21.067934] ffffffff853c52e0 ffff8801b3eda0d8 ffff8801b3ed9800 ffff8801d7db7a80 [ 21.075899] ffffffff81238961 ffff8801b3eda0d8 00000000b3eda0b0 ffff8801b3eda0d8 [ 21.083893] Call Trace: [ 21.086450] [] dump_stack+0xc1/0x128 [ 21.091786] [] print_circular_bug+0x271/0x310 [ 21.097897] [] __lock_acquire+0x2bf9/0x3640 [ 21.103836] [] ? avc_has_extended_perms+0x3fc/0xf10 [ 21.110471] [] ? avc_has_extended_perms+0xe2/0xf10 [ 21.117019] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 21.124005] [] ? mark_held_locks+0xaf/0x100 [ 21.129946] [] ? mutex_lock_nested+0x5e3/0x870 [ 21.136148] [] ? __lock_is_held+0xa1/0xf0 [ 21.141914] [] lock_acquire+0x12e/0x410 [ 21.147509] [] ? __might_fault+0xe4/0x1d0 [ 21.153279] [] __might_fault+0x14a/0x1d0 [ 21.158960] [] ? __might_fault+0xe4/0x1d0 [ 21.164728] [] ashmem_ioctl+0x3c0/0xfe0 [ 21.170321] [] ? selinux_file_ioctl+0x355/0x530 [ 21.176605] [] ? selinux_capable+0x40/0x40 [ 21.182458] [] ? get_name+0x250/0x250 [ 21.187879] [] ? compat_SyS_futex+0x1f9/0x2a0 [ 21.193991] [] compat_ashmem_ioctl+0x3e/0x50 [ 21.200027] [] compat_SyS_ioctl+0x15f/0x2050 [ 21.206051] [