[....] Starting enhanced syslogd: rsyslogd[ 11.574292] audit: type=1400 audit(1520076881.118:4): avc: denied { syslog } for pid=3597 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 '10.128.0.18' (ECDSA) to the list of known hosts. 2018/03/03 11:34:50 parsed 1 programs 2018/03/03 11:34:50 executed programs: 0 syzkaller login: [ 20.949860] IPVS: Creating netns size=2536 id=1 [ 20.967800] [ 20.969439] ====================================================== [ 20.975723] [ INFO: possible circular locking dependency detected ] [ 20.982094] 4.9.85-ge0b05e6 #57 Not tainted [ 20.986380] ------------------------------------------------------- [ 20.992749] syz-executor0/3759 is trying to acquire lock: [ 20.998251] (&mm->mmap_sem){++++++}, at: [] __might_fault+0xe4/0x1d0 [ 21.006722] but task is already holding lock: [ 21.011358] (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 21.019733] which lock already depends on the new lock. [ 21.019733] [ 21.026722] [ 21.026722] the existing dependency chain (in reverse order) is: [ 21.034311] -> #1 (ashmem_mutex){+.+.+.}: [ 21.039073] lock_acquire+0x12e/0x410 [ 21.043364] mutex_lock_nested+0xbb/0x870 [ 21.048001] ashmem_mmap+0x53/0x400 [ 21.052116] mmap_region+0x7dd/0xfd0 [ 21.056336] do_mmap+0x57b/0xbe0 [ 21.060198] vm_mmap_pgoff+0x16b/0x1b0 [ 21.064577] SyS_mmap_pgoff+0x33f/0x560 [ 21.069047] do_fast_syscall_32+0x2f5/0x870 [ 21.073857] entry_SYSENTER_compat+0x90/0xa2 [ 21.078756] -> #0 (&mm->mmap_sem){++++++}: [ 21.083601] __lock_acquire+0x2bf9/0x3640 [ 21.088245] lock_acquire+0x12e/0x410 [ 21.092541] __might_fault+0x14a/0x1d0 [ 21.096921] ashmem_ioctl+0x3c0/0xfe0 [ 21.101212] compat_ashmem_ioctl+0x3e/0x50 [ 21.105937] compat_SyS_ioctl+0x15f/0x2050 [ 21.110661] do_fast_syscall_32+0x2f5/0x870 [ 21.115481] entry_SYSENTER_compat+0x90/0xa2 [ 21.120376] [ 21.120376] other info that might help us debug this: [ 21.120376] [ 21.128487] Possible unsafe locking scenario: [ 21.128487] [ 21.134510] CPU0 CPU1 [ 21.139142] ---- ---- [ 21.143776] lock(ashmem_mutex); [ 21.147430] lock(&mm->mmap_sem); [ 21.153692] lock(ashmem_mutex); [ 21.159874] lock(&mm->mmap_sem); [ 21.163621] [ 21.163621] *** DEADLOCK *** [ 21.163621] [ 21.169656] 1 lock held by syz-executor0/3759: [ 21.174202] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 21.183130] [ 21.183130] stack backtrace: [ 21.187603] CPU: 1 PID: 3759 Comm: syz-executor0 Not tainted 4.9.85-ge0b05e6 #57 [ 21.195111] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.204435] ffff8801d829fa38 ffffffff81d95739 ffffffff853a2b20 ffffffff853a2b20 [ 21.212419] ffffffff853c32e0 ffff8801d828b8d8 ffff8801d828b000 ffff8801d829fa80 [ 21.220399] ffffffff812387f1 ffff8801d828b8d8 00000000d828b8b0 ffff8801d828b8d8 [ 21.228363] Call Trace: [ 21.230922] [] dump_stack+0xc1/0x128 [ 21.236257] [] print_circular_bug+0x271/0x310 [ 21.242372] [] __lock_acquire+0x2bf9/0x3640 [ 21.248312] [] ? avc_has_extended_perms+0x3fc/0xf10 [ 21.254947] [] ? avc_has_extended_perms+0xe2/0xf10 [ 21.261495] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 21.268477] [] ? mark_held_locks+0xaf/0x100 [ 21.274416] [] ? mutex_lock_nested+0x5e3/0x870 [ 21.280617] [] ? __lock_is_held+0xa1/0xf0 [ 21.286386] [] lock_acquire+0x12e/0x410 [ 21.291983] [] ? __might_fault+0xe4/0x1d0 [ 21.297751] [] __might_fault+0x14a/0x1d0 [ 21.303433] [] ? __might_fault+0xe4/0x1d0 [ 21.309203] [] ashmem_ioctl+0x3c0/0xfe0 [ 21.314800] [] ? selinux_file_ioctl+0x355/0x530 [ 21.321086] [] ? selinux_capable+0x40/0x40 [ 21.326938] [] ? get_name+0x250/0x250 [ 21.332357] [] ? compat_SyS_futex+0x1f9/0x2a0 [ 21.338472] [] compat_ashmem_ioctl+0x3e/0x50 [ 21.344506] [] compat_SyS_ioctl+0x15f/0x2050 [ 21.350533