[....] Starting enhanced syslogd: rsyslogd[ 12.252416] audit: type=1400 audit(1519943160.737:4): avc: denied { syslog } for pid=3487 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 '10.128.0.2' (ECDSA) to the list of known hosts. 2018/03/01 22:26:08 parsed 1 programs 2018/03/01 22:26:08 executed programs: 0 syzkaller login: [ 20.419625] IPVS: Creating netns size=2536 id=1 [ 20.438015] [ 20.439655] ====================================================== [ 20.445951] [ INFO: possible circular locking dependency detected ] [ 20.452334] 4.9.85-g4c4262a #55 Not tainted [ 20.456622] ------------------------------------------------------- [ 20.462998] syz-executor0/3648 is trying to acquire lock: [ 20.468501] (&mm->mmap_sem){++++++}, at: [] __might_fault+0xe4/0x1d0 [ 20.476970] but task is already holding lock: [ 20.481608] (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 20.489983] which lock already depends on the new lock. [ 20.489983] [ 20.496970] [ 20.496970] the existing dependency chain (in reverse order) is: [ 20.504570] -> #1 (ashmem_mutex){+.+.+.}: [ 20.509341] lock_acquire+0x12e/0x410 [ 20.513643] mutex_lock_nested+0xbb/0x870 [ 20.518292] ashmem_mmap+0x53/0x400 [ 20.522420] mmap_region+0x7dd/0xfd0 [ 20.526683] do_mmap+0x57b/0xbe0 [ 20.530546] vm_mmap_pgoff+0x16b/0x1b0 [ 20.534925] SyS_mmap_pgoff+0x33f/0x560 [ 20.539396] do_fast_syscall_32+0x2f5/0x870 [ 20.544211] entry_SYSENTER_compat+0x90/0xa2 [ 20.549109] -> #0 (&mm->mmap_sem){++++++}: [ 20.553956] __lock_acquire+0x2bf9/0x3640 [ 20.558597] lock_acquire+0x12e/0x410 [ 20.562891] __might_fault+0x14a/0x1d0 [ 20.567270] ashmem_ioctl+0x3c0/0xfe0 [ 20.571562] compat_ashmem_ioctl+0x3e/0x50 [ 20.576295] compat_SyS_ioctl+0x15f/0x2050 [ 20.581023] do_fast_syscall_32+0x2f5/0x870 [ 20.585843] entry_SYSENTER_compat+0x90/0xa2 [ 20.590738] [ 20.590738] other info that might help us debug this: [ 20.590738] [ 20.598850] Possible unsafe locking scenario: [ 20.598850] [ 20.604875] CPU0 CPU1 [ 20.609512] ---- ---- [ 20.614145] lock(ashmem_mutex); [ 20.617801] lock(&mm->mmap_sem); [ 20.624060] lock(ashmem_mutex); [ 20.630226] lock(&mm->mmap_sem); [ 20.633979] [ 20.633979] *** DEADLOCK *** [ 20.633979] [ 20.640009] 1 lock held by syz-executor0/3648: [ 20.644558] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 20.653493] [ 20.653493] stack backtrace: [ 20.657961] CPU: 1 PID: 3648 Comm: syz-executor0 Not tainted 4.9.85-g4c4262a #55 [ 20.665462] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 20.674785] ffff8801d8d7fa38 ffffffff81d95739 ffffffff853a2cd0 ffffffff853a2cd0 [ 20.682756] ffffffff853c3640 ffff8801c313d0d8 ffff8801c313c800 ffff8801d8d7fa80 [ 20.690732] ffffffff812387f1 ffff8801c313d0d8 00000000c313d0b0 ffff8801c313d0d8 [ 20.698699] Call Trace: [ 20.701259] [] dump_stack+0xc1/0x128 [ 20.706594] [] print_circular_bug+0x271/0x310 [ 20.712707] [] __lock_acquire+0x2bf9/0x3640 [ 20.718647] [] ? avc_has_extended_perms+0x3fc/0xf10 [ 20.725286] [] ? avc_has_extended_perms+0xe2/0xf10 [ 20.731841] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 20.738827] [] ? mark_held_locks+0xaf/0x100 [ 20.744773] [] ? mutex_lock_nested+0x5e3/0x870 [ 20.750978] [] ? __lock_is_held+0xa1/0xf0 [ 20.756746] [] lock_acquire+0x12e/0x410 [ 20.762344] [] ? __might_fault+0xe4/0x1d0 [ 20.768112] [] __might_fault+0x14a/0x1d0 [ 20.773792] [] ? __might_fault+0xe4/0x1d0 [ 20.779577] [] ashmem_ioctl+0x3c0/0xfe0 [ 20.785186] [] ? selinux_file_ioctl+0x355/0x530 [ 20.791481] [] ? selinux_capable+0x40/0x40 [ 20.797342] [] ? get_name+0x250/0x250 [ 20.802763] [] ? compat_SyS_futex+0x1f9/0x2a0 [ 20.808877] [] compat_ashmem_ioctl+0x3e/0x50 [ 20.814908] [] compat_SyS_ioctl+0x15f/0x2050 [ 2