[....] Starting enhanced syslogd: rsyslogd[ 12.852648] audit: type=1400 audit(1519637511.041:4): avc: denied { syslog } for pid=3652 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 mcstransd: [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] 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. executing program syzkaller login: [ 26.829044] [ 26.830705] ====================================================== [ 26.836992] [ INFO: possible circular locking dependency detected ] [ 26.843370] 4.9.84-ga9d0273 #44 Not tainted [ 26.847663] ------------------------------------------------------- [ 26.854049] syzkaller022277/3808 is trying to acquire lock: [ 26.859729] (&mm->mmap_sem){++++++}, at: [] __might_fault+0xe4/0x1d0 [ 26.868221] but task is already holding lock: [ 26.872861] (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 26.881258] which lock already depends on the new lock. [ 26.881258] [ 26.888250] [ 26.888250] the existing dependency chain (in reverse order) is: [ 26.895839] -> #1 (ashmem_mutex){+.+.+.}: [ 26.900606] lock_acquire+0x12e/0x410 [ 26.904899] mutex_lock_nested+0xbb/0x870 [ 26.909538] ashmem_mmap+0x53/0x400 [ 26.913657] mmap_region+0x7dd/0xfd0 [ 26.917860] do_mmap+0x57b/0xbe0 [ 26.921722] vm_mmap_pgoff+0x16b/0x1b0 [ 26.926099] SyS_mmap_pgoff+0x33f/0x560 [ 26.930566] SyS_mmap+0x16/0x20 [ 26.934333] do_syscall_64+0x1a4/0x490 [ 26.938710] entry_SYSCALL_64_after_swapgs+0x47/0xc5 [ 26.944298] -> #0 (&mm->mmap_sem){++++++}: [ 26.949147] __lock_acquire+0x2bf9/0x3640 [ 26.953785] lock_acquire+0x12e/0x410 [ 26.958077] __might_fault+0x14a/0x1d0 [ 26.962453] ashmem_ioctl+0x3c0/0xfe0 [ 26.966764] do_vfs_ioctl+0x1aa/0x1140 [ 26.971141] SyS_ioctl+0x8f/0xc0 [ 26.974995] do_syscall_64+0x1a4/0x490 [ 26.979374] entry_SYSCALL_64_after_swapgs+0x47/0xc5 [ 26.984965] [ 26.984965] other info that might help us debug this: [ 26.984965] [ 26.993074] Possible unsafe locking scenario: [ 26.993074] [ 26.999101] CPU0 CPU1 [ 27.003736] ---- ---- [ 27.008372] lock(ashmem_mutex); [ 27.012034] lock(&mm->mmap_sem); [ 27.018299] lock(ashmem_mutex); [ 27.024476] lock(&mm->mmap_sem); [ 27.028222] [ 27.028222] *** DEADLOCK *** [ 27.028222] [ 27.034254] 1 lock held by syzkaller022277/3808: [ 27.038979] #0: (ashmem_mutex){+.+.+.}, at: [] ashmem_ioctl+0x371/0xfe0 [ 27.047922] [ 27.047922] stack backtrace: [ 27.052393] CPU: 0 PID: 3808 Comm: syzkaller022277 Not tainted 4.9.84-ga9d0273 #44 [ 27.060069] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.069397] ffff8801d8d2f908 ffffffff81d956b9 ffffffff853a2cd0 ffffffff853a2cd0 [ 27.077387] ffffffff853c2f80 ffff8801d97908d8 ffff8801d9790000 ffff8801d8d2f950 [ 27.085372] ffffffff812387f1 ffff8801d97908d8 00000000d97908b0 ffff8801d97908d8 [ 27.093356] Call Trace: [ 27.095919] [] dump_stack+0xc1/0x128 [ 27.101258] [] print_circular_bug+0x271/0x310 [ 27.107376] [] __lock_acquire+0x2bf9/0x3640 [ 27.113319] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 27.120304] [] ? debug_check_no_locks_freed+0x2c0/0x2c0 [ 27.127297] [] ? mark_held_locks+0xaf/0x100 [ 27.133239] [] ? mutex_lock_nested+0x5e3/0x870 [ 27.139443] [] ? __lock_is_held+0xa1/0xf0 [ 27.145212] [] lock_acquire+0x12e/0x410 [ 27.150807] [] ? __might_fault+0xe4/0x1d0 [ 27.156577] [] __might_fault+0x14a/0x1d0 [ 27.162259] [] ? __might_fault+0xe4/0x1d0 [ 27.168032] [] ashmem_ioctl+0x3c0/0xfe0 [ 27.173627] [] ? vma_wants_writenotify+0x51/0x380 [ 27.180092] [] ? vma_set_page_prot+0x10f/0x180 [ 27.186296] [] ? get_name+0x250/0x250 [ 27.191718] [] ? mmap_region+0x161/0xfd0 [ 27.197401] [] ? get_name+0x250/0x250 [ 27.202823] [] do_vfs_ioctl+0x1aa/0x1140 [ 27.208506] [] ? ioctl_preallocate+0x220/0x220 [ 27.214708] [] ? selinux_file_ioctl+0x355/0x530 [ 27.220997] [] ? selinux_capable+0x40/0x40 [ 27.226858] [] ? fput+0xd