[....] Starting enhanced syslogd: rsyslogd[ 11.647348] audit: type=1400 audit(1521303619.894:4): avc: denied { syslog } for pid=3631 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[1G[[32m ok [39;49m8[?25h[?0c.
[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c.
Starting mcstransd:
[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c.
[....] Starting file context maintaining daemon: restorecond[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c.
Debian GNU/Linux 7 syzkaller ttyS0
Warning: Permanently added '10.128.0.15' (ECDSA) to the list of known hosts.
executing program
syzkaller login: [ 29.250282]
[ 29.251916] ======================================================
[ 29.258198] [ INFO: possible circular locking dependency detected ]
[ 29.264568] 4.9.87-gfc8bd0f #58 Not tainted
[ 29.268851] -------------------------------------------------------
[ 29.275217] syzkaller028250/3790 is trying to acquire lock:
[ 29.280888] (&mm->mmap_sem){++++++}, at: [<ffffffff814c2984>] __might_fault+0xe4/0x1d0
[ 29.289344] but task is already holding lock:
[ 29.293974] (ashmem_mutex){+.+.+.}, at: [<ffffffff82d4b891>] ashmem_ioctl+0x371/0xfe0
[ 29.302342] which lock already depends on the new lock.
[ 29.302342]
[ 29.309318]
[ 29.309318] the existing dependency chain (in reverse order) is:
[ 29.316901]
-> #1 (ashmem_mutex){+.+.+.}:
[ 29.321649] lock_acquire+0x12e/0x410
[ 29.325935] mutex_lock_nested+0xbb/0x870
[ 29.330568] ashmem_mmap+0x53/0x400
[ 29.334681] mmap_region+0x7dd/0xfd0
[ 29.338880] do_mmap+0x57b/0xbe0
[ 29.342736] vm_mmap_pgoff+0x16b/0x1b0
[ 29.347111] SyS_mmap_pgoff+0x33f/0x560
[ 29.351570] SyS_mmap+0x16/0x20
[ 29.355338] do_syscall_64+0x1a4/0x490
[ 29.359710] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
[ 29.365298]
-> #0 (&mm->mmap_sem){++++++}:
[ 29.370128] __lock_acquire+0x2bf9/0x3640
[ 29.374762] lock_acquire+0x12e/0x410
[ 29.379047] __might_fault+0x14a/0x1d0
[ 29.383419] ashmem_ioctl+0x3c0/0xfe0
[ 29.387707] do_vfs_ioctl+0x1aa/0x1140
[ 29.392081] SyS_ioctl+0x8f/0xc0
[ 29.395933] do_syscall_64+0x1a4/0x490
[ 29.400304] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
[ 29.405892]
[ 29.405892] other info that might help us debug this:
[ 29.405892]
[ 29.413996] Possible unsafe locking scenario:
[ 29.413996]
[ 29.420020] CPU0 CPU1
[ 29.424653] ---- ----
[ 29.429282] lock(ashmem_mutex);
[ 29.432934] lock(&mm->mmap_sem);
[ 29.439187] lock(ashmem_mutex);
[ 29.445352] lock(&mm->mmap_sem);
[ 29.449083]
[ 29.449083] *** DEADLOCK ***
[ 29.449083]
[ 29.455105] 1 lock held by syzkaller028250/3790:
[ 29.459822] #0: (ashmem_mutex){+.+.+.}, at: [<ffffffff82d4b891>] ashmem_ioctl+0x371/0xfe0
[ 29.468736]
[ 29.468736] stack backtrace:
[ 29.473201] CPU: 1 PID: 3790 Comm: syzkaller028250 Not tainted 4.9.87-gfc8bd0f #58
[ 29.480873] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[ 29.490192] ffff8801d875f908 ffffffff81d95bd9 ffffffff853a4b20 ffffffff853a4b20
[ 29.498146] ffffffff853c4710 ffff8801b98fe8d8 ffff8801b98fe000 ffff8801d875f950
[ 29.506103] ffffffff81238961 ffff8801b98fe8d8 00000000b98fe8b0 ffff8801b98fe8d8
[ 29.514061] Call Trace:
[ 29.516617] [<ffffffff81d95bd9>] dump_stack+0xc1/0x128
[ 29.521950] [<ffffffff81238961>] print_circular_bug+0x271/0x310
[ 29.528060] [<ffffffff8123ed99>] __lock_acquire+0x2bf9/0x3640
[ 29.533995] [<ffffffff8123c1a0>] ? debug_check_no_locks_freed+0x2c0/0x2c0
[ 29.540972] [<ffffffff8123c1a0>] ? debug_check_no_locks_freed+0x2c0/0x2c0
[ 29.547952] [<ffffffff8123b58f>] ? mark_held_locks+0xaf/0x100
[ 29.553889] [<ffffffff838ad2e3>] ? mutex_lock_nested+0x5e3/0x870
[ 29.560085] [<ffffffff81234e71>] ? __lock_is_held+0xa1/0xf0
[ 29.565846] [<ffffffff8124021e>] lock_acquire+0x12e/0x410
[ 29.571435] [<ffffffff814c2984>] ? __might_fault+0xe4/0x1d0
[ 29.577198] [<ffffffff814c29ea>] __might_fault+0x14a/0x1d0
[ 29.582872] [<ffffffff814c2984>] ? __might_fault+0xe4/0x1d0
[ 29.588636] [<ffffffff82d4b8e0>] ashmem_ioctl+0x3c0/0xfe0
[ 29.594225] [<ffffffff814e2931>] ? vma_wants_writenotify+0x51/0x380
[ 29.600680] [<ffffffff814e2d6f>] ? vma_set_page_prot+0x10f/0x180
[ 29.606876] [<ffffffff82d4b520>] ? get_name+0x250/0x250
[ 29.612293] [<ffffffff814e6fd1>] ? mmap_region+0x161/0xfd0
[ 29.617971] [<ffffffff82d4b520>] ? get_name+0x250/0x250
[ 29.623390] [<ffffffff815aed4a>] do_vfs_ioctl+0x1aa/0x1140
[ 29.629068] [<ffffffff815aeba0>] ? ioctl_preallocate+0x220/0x220
[ 29.635278] [<ffffffff81beb765>] ? selinux_file_ioctl+0x355/0x530
[ 29.641563] [<ffffffff81beb410>] ? selinux_capable+0x40/0x40
[ 29.647413] [<ffffffff81575952>] ? fput+0xd2/0x140