[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 14.672465] cron (4023) used greatest stack depth: 16488 bytes left 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 syzkaller login: [ 19.862440] audit: type=1400 audit(1520889698.706:6): avc: denied { map } for pid=4114 comm="bash" path="/bin/bash" dev="sda1" ino=1457 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 Warning: Permanently added '10.128.0.16' (ECDSA) to the list of known hosts. executing program [ 27.280555] audit: type=1400 audit(1520889706.124:7): avc: denied { map } for pid=4128 comm="syzkaller630279" path="/root/syzkaller630279704" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 [ 27.283809] [ 27.306480] audit: type=1400 audit(1520889706.124:8): avc: denied { map } for pid=4128 comm="syzkaller630279" path="/dev/ashmem" dev="devtmpfs" ino=1139 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:device_t:s0 tclass=chr_file permissive=1 [ 27.308044] ====================================================== [ 27.308046] WARNING: possible circular locking dependency detected [ 27.308050] 4.16.0-rc5+ #351 Not tainted [ 27.308051] ------------------------------------------------------ [ 27.308055] syzkaller630279/4128 is trying to acquire lock: [ 27.308056] (&mm->mmap_sem){++++}, at: [<000000001d32bb58>] __might_fault+0xe0/0x1d0 [ 27.308079] [ 27.308079] but task is already holding lock: [ 27.375179] (ashmem_mutex){+.+.}, at: [<00000000ed7c74f0>] ashmem_ioctl+0x3db/0x11b0 [ 27.383136] [ 27.383136] which lock already depends on the new lock. [ 27.383136] [ 27.391417] [ 27.391417] the existing dependency chain (in reverse order) is: [ 27.399003] [ 27.399003] -> #1 (ashmem_mutex){+.+.}: [ 27.404439] __mutex_lock+0x16f/0x1a80 [ 27.408814] mutex_lock_nested+0x16/0x20 [ 27.413364] ashmem_mmap+0x53/0x410 [ 27.417478] mmap_region+0xa99/0x15a0 [ 27.421767] do_mmap+0x6c0/0xe00 [ 27.425622] vm_mmap_pgoff+0x1de/0x280 [ 27.429998] SyS_mmap_pgoff+0x462/0x5f0 [ 27.434465] SyS_mmap+0x16/0x20 [ 27.438238] do_syscall_64+0x281/0x940 [ 27.442617] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 27.448292] [ 27.448292] -> #0 (&mm->mmap_sem){++++}: [ 27.453803] lock_acquire+0x1d5/0x580 [ 27.458097] __might_fault+0x13a/0x1d0 [ 27.462473] _copy_from_user+0x2c/0x110 [ 27.466935] ashmem_ioctl+0x438/0x11b0 [ 27.471308] do_vfs_ioctl+0x1b1/0x1520 [ 27.475685] SyS_ioctl+0x8f/0xc0 [ 27.479538] do_syscall_64+0x281/0x940 [ 27.483913] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 27.489586] [ 27.489586] other info that might help us debug this: [ 27.489586] [ 27.497691] Possible unsafe locking scenario: [ 27.497691] [ 27.503716] CPU0 CPU1 [ 27.508348] ---- ---- [ 27.512979] lock(ashmem_mutex); [ 27.516400] lock(&mm->mmap_sem); [ 27.522426] lock(ashmem_mutex); [ 27.528375] lock(&mm->mmap_sem); [ 27.531884] [ 27.531884] *** DEADLOCK *** [ 27.531884] [ 27.537909] 1 lock held by syzkaller630279/4128: [ 27.542633] #0: (ashmem_mutex){+.+.}, at: [<00000000ed7c74f0>] ashmem_ioctl+0x3db/0x11b0 [ 27.551009] [ 27.551009] stack backtrace: [ 27.555485] CPU: 1 PID: 4128 Comm: syzkaller630279 Not tainted 4.16.0-rc5+ #351 [ 27.562900] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.572222] Call Trace: [ 27.574784] dump_stack+0x194/0x24d [ 27.578387] ? arch_local_irq_restore+0x53/0x53 [ 27.583032] print_circular_bug.isra.38+0x2cd/0x2dc [ 27.588021] ? save_trace+0xe0/0x2b0 [ 27.591712] __lock_acquire+0x30a8/0x3e00 [ 27.595826] ? ashmem_ioctl+0x3db/0x11b0 [ 27.599858] ? debug_check_no_locks_freed+0x3c0/0x3c0 [ 27.605021] ? __might_sleep+0x95/0x190 [ 27.608964] ? ashmem_ioctl+0x3db/0x11b0 [ 27.612994] ? __mutex_lock+0x16f/0x1a80 [ 27.617031] ? ashmem_ioctl+0x3db/0x11b0 [ 27.621064] ? proc_nr_files+0x60/0x60 [ 27.624927] ? ashmem_ioctl+0x3db/0x11b0 [ 27.628956] ? find_held_lock+0x35/0x1d0 [ 27.632984] ? mutex_lock_io_nested+0x1900/0x1900 [ 27.637800] ? uprobe_mmap+0x15a/0xc90 [ 27.641660] ? lock_downgrade+0x980/0x980 [ 27.646106] ? __mutex_unlock_slowpath+0xe9/0xac0 [ 27.650918] ? find_held_lock+0x35/0x1d0 [ 27.654952] ? lock_downgrade+0x980/0x980 [ 27.659072] ? vma_set_page_prot+0x16b/0x230 [ 27.663451] lock_acquire+0x1d5/0x580 [ 27.667219] ? lock_acquire+0x1d5/0x580 [ 27.671162] ? __might_fault+0xe0/0x1d0 [ 27.675107] ? lock_release+0xa40/0xa40 [ 27.679051] ? check_same_owner+0x320/0x320 [ 27.683342] ? __might_sleep+0x95/0x190 [ 27.687285] __might_fault+0x13a/0x1d0 [ 27.691139] ? __might_fault+0xe0/0x1d0 [ 27.695086] _copy_from_user+0x2c/0x110 [ 27.699032] ashmem_ioctl+0x438/0x11b0 [ 27.702891] ? ashmem_release+0x190/0x190 [ 27.707008] ? check_same_owner+0x320/0x320 [ 27.711304] ? down_read_killable+0x180/0x180 [ 27.715766] ? rcu_note_context_switch+0x710/0x710 [ 27.720671] ? ashmem_release+0x190/0x190 [ 27.724785] do_vfs_ioctl+0x1b1/0x1520 [ 27.728639] ? ioctl_preallocate+0x2b0/0x2b0 [ 27.733022] ? selinux_capable+0x40/0x40 [ 27.737055] ? putname+0xf3/0x130 [ 27.740477] ? fput+0xd2/0x140 [ 27.743639] ? SyS_mmap_pgoff+0x243/0x5f0 [ 27.747760] ? security_file_ioctl+0x7d/0xb0 [ 27.752139] ? security_file_ioctl+0x89/0xb0 [ 27.756515] SyS_ioctl+0x8f/0xc0 [ 27.759848] ? do_vfs_ioctl+0x1520/0x1520 [ 27.763966] do_syscall_64+0x281/0x940 [ 27.767820] ? __do_page_fault+0xc90/0xc90 [ 27.772031] ? trace_event_raw_event_sys_exit+0x260/0x260 [ 27.777542] ? syscall_return_slowpath+0x550/0x550 [ 27.782440] ? syscall_return_slowpath+0x2ac/0x550 [ 27.787339] ? entry_SYSCALL_64_after_hwframe+0x52/0xb7 [ 27.792673] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 27.797494] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 27.802659] RIP: 0033:0x43fd19 [ 27.805819] RSP: 002b:00007ffdf4578d98 EFLAGS: 00000217 ORIG_RAX: 0000000000000010 [ 27.813494] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fd19 [ 27.820731] RDX: 0000000000000000 RSI: 0000000000007709 RDI: 0000000000000003 [ 27.827968] RBP: 00000000006ca018 R08: 000000000000000