[....] Starting enhanced syslogd: rsyslogd[ 12.933408] audit: type=1400 audit(1520235852.120:4): avc: denied { syslog } for pid=3646 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 '10.128.0.20' (ECDSA) to the list of known hosts. 2018/03/05 07:44:25 parsed 1 programs 2018/03/05 07:44:25 executed programs: 0 syzkaller login: [ 26.809974] IPVS: Creating netns size=2536 id=1 [ 26.829185] [ 26.830833] ====================================================== [ 26.837165] [ INFO: possible circular locking dependency detected ] [ 26.843541] 4.9.86-gb324a70 #58 Not tainted [ 26.847839] ------------------------------------------------------- [ 26.854213] syz-executor0/3815 is trying to acquire lock: [ 26.859717] (&mm->mmap_sem){++++++}, at: [] __might_fault+0xe4/0x1d0 [ 26.868191] but task is already holding lock: [ 26.872832] (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 26.881272] which lock already depends on the new lock. [ 26.881272] [ 26.888257] [ 26.888257] the existing dependency chain (in reverse order) is: [ 26.895847] -> #1 (ashmem_mutex){+.+.+.}: [ 26.900626] lock_acquire+0x12e/0x410 [ 26.904923] mutex_lock_nested+0xbb/0x870 [ 26.909573] ashmem_mmap+0x53/0x400 [ 26.913693] mmap_region+0x7dd/0xfd0 [ 26.917896] do_mmap+0x57b/0xbe0 [ 26.921758] vm_mmap_pgoff+0x16b/0x1b0 [ 26.926142] SyS_mmap_pgoff+0x33f/0x560 [ 26.930621] do_fast_syscall_32+0x2f5/0x870 [ 26.935436] entry_SYSENTER_compat+0x90/0xa2 [ 26.940339] -> #0 (&mm->mmap_sem){++++++}: [ 26.945195] __lock_acquire+0x2bf9/0x3640 [ 26.949833] lock_acquire+0x12e/0x410 [ 26.954126] __might_fault+0x14a/0x1d0 [ 26.958506] ashmem_ioctl+0x3c0/0xfe0 [ 26.962797] compat_ashmem_ioctl+0x3e/0x50 [ 26.967523] compat_SyS_ioctl+0x15f/0x2050 [ 26.972251] do_fast_syscall_32+0x2f5/0x870 [ 26.977063] entry_SYSENTER_compat+0x90/0xa2 [ 26.981958] [ 26.981958] other info that might help us debug this: [ 26.981958] [ 26.990069] Possible unsafe locking scenario: [ 26.990069] [ 26.996095] CPU0 CPU1 [ 27.000741] ---- ---- [ 27.005379] lock(ashmem_mutex); [ 27.009047] lock(&mm->mmap_sem); [ 27.015307] lock(ashmem_mutex); [ 27.021491] lock(&mm->mmap_sem); [ 27.025240] [ 27.025240] *** DEADLOCK *** [ 27.025240] [ 27.031275] 1 lock held by syz-executor0/3815: [ 27.035824] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 27.044777] [ 27.044777] stack backtrace: [ 27.049245] CPU: 0 PID: 3815 Comm: syz-executor0 Not tainted 4.9.86-gb324a70 #58 [ 27.056748] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.066076] ffff8801d7e97a38 ffffffff81d956f9 ffffffff853a4cd0 ffffffff853a4cd0 [ 27.074069] ffffffff853c57f0 ffff8801d89950d8 ffff8801d8994800 ffff8801d7e97a80 [ 27.082050] ffffffff812387f1 ffff8801d89950d8 00000000d89950b0 ffff8801d89950d8 [ 27.090026] Call Trace: [ 27.092590] [] dump_stack+0xc1/0x128 [ 27.097929] [] print_circular_bug+0x271/0x310 [ 27.104046] [] __lock_acquire+0x2bf9/0x3640 [ 27.109993] [] ? avc_has_extended_perms+0x3fc/0xf10 [ 27.116630] [] ? avc_has_extended_perms+0xe2/0xf10 [ 27.123182] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 27.130166] [] ? mark_held_locks+0xaf/0x100 [ 27.136112] [] ? mutex_lock_nested+0x5e3/0x870 [ 27.142331] [] ? __lock_is_held+0xa1/0xf0 [ 27.148099] [] lock_acquire+0x12e/0x410 [ 27.153699] [] ? __might_fault+0xe4/0x1d0 [ 27.159472] [] __might_fault+0x14a/0x1d0 [ 27.165167] [] ? __might_fault+0xe4/0x1d0 [ 27.170936] [] ashmem_ioctl+0x3c0/0xfe0 [ 27.176534] [] ? selinux_file_ioctl+0x355/0x530 [ 27.182823] [] ? selinux_capable+0x40/0x40 [ 27.188680] [] ? get_name+0x250/0x250 [ 27.194104] [] ? compat_SyS_futex+0x1f9/0x2a0 [ 27.200231] [] compat_ashmem_ioctl+0x3e/0x50 [ 27.206263] [] compat_SyS_ioctl+0x15f/0x