[....] Starting enhanced syslogd: rsyslogd[ 13.337905] audit: type=1400 audit(1520889727.690:4): avc: denied { syslog } for pid=3651 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 '10.128.10.7' (ECDSA) to the list of known hosts. 2018/03/12 21:22:20 parsed 1 programs 2018/03/12 21:22:20 executed programs: 0 syzkaller login: [ 26.357125] IPVS: Creating netns size=2536 id=1 [ 26.374923] [ 26.376556] ====================================================== [ 26.382839] [ INFO: possible circular locking dependency detected ] [ 26.389210] 4.9.87-ga290494 #1 Not tainted [ 26.393407] ------------------------------------------------------- [ 26.399777] syz-executor0/3820 is trying to acquire lock: [ 26.405278] (&mm->mmap_sem){++++++}, at: [] __might_fault+0xe4/0x1d0 [ 26.413746] but task is already holding lock: [ 26.418390] (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 26.426773] which lock already depends on the new lock. [ 26.426773] [ 26.433753] [ 26.433753] the existing dependency chain (in reverse order) is: [ 26.441337] -> #1 (ashmem_mutex){+.+.+.}: [ 26.446095] lock_acquire+0x12e/0x410 [ 26.450390] mutex_lock_nested+0xbb/0x870 [ 26.455026] ashmem_mmap+0x53/0x400 [ 26.459140] mmap_region+0x7dd/0xfd0 [ 26.463339] do_mmap+0x57b/0xbe0 [ 26.467198] vm_mmap_pgoff+0x16b/0x1b0 [ 26.471574] SyS_mmap_pgoff+0x33f/0x560 [ 26.476046] do_fast_syscall_32+0x2f5/0x870 [ 26.480870] entry_SYSENTER_compat+0x90/0xa2 [ 26.485768] -> #0 (&mm->mmap_sem){++++++}: [ 26.490614] __lock_acquire+0x2bf9/0x3640 [ 26.495250] lock_acquire+0x12e/0x410 [ 26.499541] __might_fault+0x14a/0x1d0 [ 26.503919] ashmem_ioctl+0x3c0/0xfe0 [ 26.508205] compat_ashmem_ioctl+0x3e/0x50 [ 26.512927] compat_SyS_ioctl+0x15f/0x2050 [ 26.517650] do_fast_syscall_32+0x2f5/0x870 [ 26.522460] entry_SYSENTER_compat+0x90/0xa2 [ 26.527356] [ 26.527356] other info that might help us debug this: [ 26.527356] [ 26.535466] Possible unsafe locking scenario: [ 26.535466] [ 26.541488] CPU0 CPU1 [ 26.546120] ---- ---- [ 26.550754] lock(ashmem_mutex); [ 26.554407] lock(&mm->mmap_sem); [ 26.560657] lock(ashmem_mutex); [ 26.566822] lock(&mm->mmap_sem); [ 26.570566] [ 26.570566] *** DEADLOCK *** [ 26.570566] [ 26.576592] 1 lock held by syz-executor0/3820: [ 26.581140] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 26.590075] [ 26.590075] stack backtrace: [ 26.594543] CPU: 0 PID: 3820 Comm: syz-executor0 Not tainted 4.9.87-ga290494 #1 [ 26.601961] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.611283] ffff8801d8877a38 ffffffff81d95a19 ffffffff853a4b20 ffffffff853a4b20 [ 26.619250] ffffffff853c52e0 ffff8801d7e268d8 ffff8801d7e26000 ffff8801d8877a80 [ 26.627237] ffffffff81238961 ffff8801d7e268d8 00000000d7e268b0 ffff8801d7e268d8 [ 26.635210] Call Trace: [ 26.637772] [] dump_stack+0xc1/0x128 [ 26.643105] [] print_circular_bug+0x271/0x310 [ 26.649222] [] __lock_acquire+0x2bf9/0x3640 [ 26.655163] [] ? avc_has_extended_perms+0x3fc/0xf10 [ 26.661795] [] ? avc_has_extended_perms+0xe2/0xf10 [ 26.668350] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 26.675333] [] ? mark_held_locks+0xaf/0x100 [ 26.681271] [] ? mutex_lock_nested+0x5e3/0x870 [ 26.687471] [] ? __lock_is_held+0xa1/0xf0 [ 26.693240] [] lock_acquire+0x12e/0x410 [ 26.698833] [] ? __might_fault+0xe4/0x1d0 [ 26.704608] [] __might_fault+0x14a/0x1d0 [ 26.710289] [] ? __might_fault+0xe4/0x1d0 [ 26.716054] [] ashmem_ioctl+0x3c0/0xfe0 [ 26.721649] [] ? selinux_file_ioctl+0x355/0x530 [ 26.727936] [] ? selinux_capable+0x40/0x40 [ 26.733790] [] ? get_name+0x250/0x250 [ 26.739214] [] ? compat_SyS_futex+0x1f9/0x2a0 [ 26.745327] [] compat_ashmem_ioctl+0x3e/0x50 [ 26.751358] [] compat_SyS_ioctl+0x15f/0x2050 [ 26.757383] [