[   38.806102] audit: type=1800 audit(1550799859.467:32): pid=7742 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:kernel_t:s0 op=collect_data cause=failed(directio) comm="startpar" name="ssh" dev="sda1" ino=2417 res=0
[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c.
Starting mcstransd: 
[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c.
[....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c.
[   39.556767] audit: type=1800 audit(1550799860.287:33): pid=7742 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:kernel_t:s0 op=collect_data cause=failed(directio) comm="startpar" name="rc.local" dev="sda1" ino=2432 res=0

Debian GNU/Linux 7 syzkaller ttyS0

Warning: Permanently added '10.128.0.37' (ECDSA) to the list of known hosts.
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syzkaller login: [  115.275303] kauditd_printk_skb: 2 callbacks suppressed
[  115.275321] audit: type=1400 audit(1550799935.997:36): avc:  denied  { map } for  pid=7932 comm="syz-executor712" path="/root/syz-executor712951446" dev="sda1" ino=1426 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
[  115.316588] audit: type=1400 audit(1550799936.017:37): avc:  denied  { map } for  pid=7940 comm="syz-executor712" path="/dev/ashmem" dev="devtmpfs" ino=17238 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:device_t:s0 tclass=chr_file permissive=1
[  115.329228] hrtimer: interrupt took 52340 ns
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[  122.931691] 
[  122.933351] ======================================================
[  122.939660] WARNING: possible circular locking dependency detected
[  122.945975] 5.0.0-rc7+ #82 Not tainted
[  122.949850] ------------------------------------------------------
[  122.956165] syz-executor712/8382 is trying to acquire lock:
[  122.961871] 00000000ecbf114d (&mm->mmap_sem){++++}, at: __do_page_fault+0x9c2/0xd60
[  122.969690] 
[  122.969690] but task is already holding lock:
[  122.975651] 00000000e85ceced (&sb->s_type->i_mutex_key#12){+.+.}, at: generic_file_write_iter+0xdf/0x610
[  122.985294] 
[  122.985294] which lock already depends on the new lock.
[  122.985294] 
[  122.993601] 
[  122.993601] the existing dependency chain (in reverse order) is:
[  123.001215] 
[  123.001215] -> #2 (&sb->s_type->i_mutex_key#12){+.+.}:
[  123.007990]        down_write+0x38/0x90
[  123.011968]        shmem_fallocate+0x15a/0xc60
[  123.016554]        ashmem_shrink_scan+0x1d7/0x4f0
[  123.021395]        ashmem_ioctl+0x2f0/0x11a0
[  123.025804]        do_vfs_ioctl+0xd6e/0x1390
[  123.030209]        ksys_ioctl+0xab/0xd0
[  123.034184]        __x64_sys_ioctl+0x73/0xb0
[  123.038593]        do_syscall_64+0x103/0x610
[  123.043007]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  123.048711] 
[  123.048711] -> #1 (ashmem_mutex){+.+.}:
[  123.054172]        __mutex_lock+0xf7/0x1310
[  123.058494]        mutex_lock_nested+0x16/0x20
[  123.063080]        ashmem_mmap+0x55/0x520
[  123.067232]        mmap_region+0xc37/0x1760
[  123.071554]        do_mmap+0x8e2/0x1080
[  123.075524]        vm_mmap_pgoff+0x1c5/0x230
[  123.079928]        ksys_mmap_pgoff+0x4aa/0x630
[  123.084502]        __x64_sys_mmap+0xe9/0x1b0
[  123.088907]        do_syscall_64+0x103/0x610
[  123.093313]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  123.099010] 
[  123.099010] -> #0 (&mm->mmap_sem){++++}:
[  123.104550]        lock_acquire+0x16f/0x3f0
[  123.108863]        down_read+0x3b/0x90
[  123.112742]        __do_page_fault+0x9c2/0xd60
[  123.117318]        do_page_fault+0x71/0x581
[  123.121632]        page_fault+0x1e/0x30
[  123.125602]        iov_iter_fault_in_readable+0x377/0x450
[  123.131134]        generic_perform_write+0x195/0x530
[  123.136233]        __generic_file_write_iter+0x25e/0x630
[  123.141680]        generic_file_write_iter+0x360/0x610
[  123.146951]        __vfs_write+0x613/0x8e0
[  123.151179]        vfs_write+0x20c/0x580
[  123.155229]        ksys_write+0xea/0x1f0
[  123.159293]        __x64_sys_write+0x73/0xb0
[  123.163693]        do_syscall_64+0x103/0x610
[  123.168097]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  123.173791] 
[  123.173791] other info that might help us debug this:
[  123.173791] 
[  123.181918] Chain exists of:
[  123.181918]   &mm->mmap_sem --> ashmem_mutex --> &sb->s_type->i_mutex_key#12
[  123.181918] 
[  123.193445]  Possible unsafe locking scenario:
[  123.193445] 
[  123.199485]        CPU0                    CPU1
[  123.204483]        ----                    ----
[  123.209134]   lock(&sb->s_type->i_mutex_key#12);
[  123.213879]                                lock(ashmem_mutex);
[  123.219838]                                lock(&sb->s_type->i_mutex_key#12);
[  123.227107]   lock(&mm->mmap_sem);
[  123.230633] 
[  123.230633]  *** DEADLOCK ***
[  123.230633] 
[  123.236682] 2 locks held by syz-executor712/8382:
[  123.241504]  #0: 00000000a77b1cb8 (sb_writers#6){.+.+}, at: vfs_write+0x429/0x580
[  123.249137]  #1: 00000000e85ceced (&sb->s_type->i_mutex_key#12){+.+.}, at: generic_file_write_iter+0xdf/0x610
[  123.259200] 
[  123.259200] stack backtrace:
[  123.263690] CPU: 0 PID: 8382 Comm: syz-executor712 Not tainted 5.0.0-rc7+ #82
[  123.270955] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[  123.280297] Call Trace:
[  123.282887]  dump_stack+0x172/0x1f0
[  123.286515]  print_circular_bug.isra.0.cold+0x1cc/0x28f
[  123.291874]  __lock_acquire+0x2f00/0x4700
[  123.296019]  ? retint_kernel+0x2d/0x2d
[  123.299904]  ? trace_hardirqs_on_caller+0x6a/0x220
[  123.304831]  ? mark_held_locks+0x100/0x100
[  123.309064]  ? iov_iter_fault_in_readable+0x377/0x450
[  123.314249]  ? cmp_ex_sort+0xd0/0xd0
[  123.317974]  ? cmp_ex_search+0x14/0xb0
[  123.321854]  ? __lock_is_held+0xb6/0x140
[  123.325927]  lock_acquire+0x16f/0x3f0
[  123.329724]  ? __do_page_fault+0x9c2/0xd60
[  123.333956]  down_read+0x3b/0x90
[  123.337318]  ? __do_page_fault+0x9c2/0xd60
[  123.341551]  __do_page_fault+0x9c2/0xd60
[  123.345612]  do_page_fault+0x71/0x581
[  123.349411]  page_fault+0x1e/0x30
[  123.352860] RIP: 0010:iov_iter_fault_in_readable+0x377/0x450
[  123.358649] Code: 89 f6 41 88 57 e0 e8 b8 2b 47 fe 45 85 f6 74 c1 e9 70 fe ff ff e8 29 2a 47 fe 0f 1f 00 0f ae e8 44 89 f0 48 8b 8d 68 ff ff ff <8a> 11 89 c3 0f 1f 00 41 88 57 d0 31 ff 89 de e8 85 2b 47 fe 85 db
[  123.377547] RSP: 0018:ffff88808f1c79b8 EFLAGS: 00010293
[  123.382901] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000002020053f
[  123.390164] RDX: 0000000000000000 RSI: ffffffff8328b757 RDI: 0000000000000007
[  123.397428] RBP: ffff88808f1c7a58 R08: ffff8880980d2140 R09: fffff94000486be7
[  123.404893] R10: fffff94000486be6 R11: ffffea0002435f37 R12: 0000000000001000
[  123.412159] R13: 0000000000001000 R14: 0000000000000000 R15: ffff88808f1c7a30
[  123.419436]  ? iov_iter_fault_in_readable+0x367/0x450
[  123.424621]  ? iov_iter_fault_in_readable+0x367/0x450
[  123.429805]  ? copy_page_from_iter+0x750/0x750
[  123.434387]  generic_perform_write+0x195/0x530
[  123.438965]  ? page_endio+0x780/0x780
[  123.442763]  ? current_time+0x140/0x140
[  123.446739]  __generic_file_write_iter+0x25e/0x630
[  123.451663]  ? __sanitizer_cov_trace_cmp8+0x18/0x20
[  123.456674]  generic_file_write_iter+0x360/0x610
[  123.461428]  ? __generic_file_write_iter+0x630/0x630
[  123.466523]  ? __vfs_write+0x203/0x8e0
[  123.470401]  ? __sanitizer_cov_trace_const_cmp8+0x18/0x20
[  123.475933]  ? iov_iter_init+0xea/0x220
[  123.479901]  __vfs_write+0x613/0x8e0
[  123.483612]  ? kernel_read+0x120/0x120
[  123.487498]  ? rcu_read_lock_sched_held+0x110/0x130
[  123.492510]  ? rcu_sync_lockdep_assert+0x73/0xb0
[  123.497270]  ? __sanitizer_cov_trace_const_cmp4+0x16/0x20
[  123.502821]  ? __sb_start_write+0x1ac/0x360
[  123.507140]  vfs_write+0x20c/0x580
[  123.510677]  ksys_write+0xea/0x1f0
[  123.514211]  ? __ia32_sys_read+0xb0/0xb0
[  123.518280]  ? do_syscall_64+0x26/0x610
[  123.522248]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  123.527617]  ? do_syscall_64+0x26/0x610
[  123.531608]  __x64_sys_write+0x73/0xb0
[  123.535492]  do_syscall_64+0x103/0x610
[  123.539375]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  123.544554] RIP: 0033:0x446599
[  123.547739] Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
[  123.566662] RSP: 002b:00007f5fafbdadb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[  123.574356] RAX: ffffffffffffffda RBX: 00000000006dbc28 RCX: 0000000000446599
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[  123.581618] RDX: 00000000fffffda2 RSI: 0000000020000540 RDI: 0000000000000005
[  123.588894] RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000
[  123.596164] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c
[  123.603425] R13: 00007fff2aee598f R14: 00007f5fafbdb9c0 R15: 0000000000000000
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