[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c.
[....] Starting OpenBSD Secure Shell server: sshd[   22.660012] random: sshd: uninitialized urandom read (32 bytes read)
[?25l[?1c7[ ok 8[?25h[?0c.

Debian GNU/Linux 7 syzkaller ttyS0

syzkaller login: [   28.016044] random: sshd: uninitialized urandom read (32 bytes read)
[   28.432801] random: sshd: uninitialized urandom read (32 bytes read)
[   28.994902] random: sshd: uninitialized urandom read (32 bytes read)
[   29.172594] random: sshd: uninitialized urandom read (32 bytes read)
Warning: Permanently added '10.128.10.9' (ECDSA) to the list of known hosts.
[   34.848189] random: sshd: uninitialized urandom read (32 bytes read)
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[   52.836366] 
[   52.838025] ======================================================
[   52.844323] WARNING: possible circular locking dependency detected
[   52.850618] 4.19.0-rc1-next-20180831+ #53 Not tainted
[   52.855794] ------------------------------------------------------
[   52.862091] syz-executor560/5342 is trying to acquire lock:
[   52.867777] 00000000d0c295b6 (&mm->mmap_sem){++++}, at: __might_fault+0xfb/0x1e0
[   52.875310] 
[   52.875310] but task is already holding lock:
[   52.881256] 000000000e449f78 (&rp->fetch_lock){+.+.}, at: mon_bin_get_event+0x3f/0x460
[   52.889301] 
[   52.889301] which lock already depends on the new lock.
[   52.889301] 
[   52.897600] 
[   52.897600] the existing dependency chain (in reverse order) is:
[   52.905202] 
[   52.905202] -> #1 (&rp->fetch_lock){+.+.}:
[   52.910905]        __mutex_lock+0x171/0x1700
[   52.915291]        mutex_lock_nested+0x16/0x20
[   52.919864]        mon_bin_vma_fault+0xdc/0x4a0
[   52.924517]        __do_fault+0xee/0x450
[   52.928556]        __handle_mm_fault+0x13c6/0x4350
[   52.933469]        handle_mm_fault+0x53e/0xc80
[   52.938037]        __get_user_pages+0x823/0x1b50
[   52.942783]        populate_vma_page_range+0x2db/0x3d0
[   52.948040]        __mm_populate+0x286/0x4d0
[   52.952430]        vm_mmap_pgoff+0x27f/0x2c0
[   52.956822]        ksys_mmap_pgoff+0x4da/0x660
[   52.961383]        __x64_sys_mmap+0xe9/0x1b0
[   52.965782]        do_syscall_64+0x1b9/0x820
[   52.970175]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   52.975860] 
[   52.975860] -> #0 (&mm->mmap_sem){++++}:
[   52.981387]        lock_acquire+0x1e4/0x4f0
[   52.985685]        __might_fault+0x155/0x1e0
[   52.990077]        _copy_to_user+0x30/0x110
[   52.994380]        mon_bin_get_event+0x116/0x460
[   52.999115]        mon_bin_ioctl+0x459/0xe80
[   53.003506]        do_vfs_ioctl+0x1de/0x1720
[   53.007954]        ksys_ioctl+0xa9/0xd0
[   53.011917]        __x64_sys_ioctl+0x73/0xb0
[   53.016311]        do_syscall_64+0x1b9/0x820
[   53.020701]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   53.026389] 
[   53.026389] other info that might help us debug this:
[   53.026389] 
[   53.034508]  Possible unsafe locking scenario:
[   53.034508] 
[   53.040590]        CPU0                    CPU1
[   53.045238]        ----                    ----
[   53.049881]   lock(&rp->fetch_lock);
[   53.053571]                                lock(&mm->mmap_sem);
[   53.059608]                                lock(&rp->fetch_lock);
[   53.065828]   lock(&mm->mmap_sem);
[   53.069347] 
[   53.069347]  *** DEADLOCK ***
[   53.069347] 
[   53.075387] 1 lock held by syz-executor560/5342:
[   53.080231]  #0: 000000000e449f78 (&rp->fetch_lock){+.+.}, at: mon_bin_get_event+0x3f/0x460
[   53.088716] 
[   53.088716] stack backtrace:
[   53.093207] CPU: 0 PID: 5342 Comm: syz-executor560 Not tainted 4.19.0-rc1-next-20180831+ #53
[   53.101769] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[   53.111107] Call Trace:
[   53.113680]  dump_stack+0x1c9/0x2b4
[   53.117295]  ? dump_stack_print_info.cold.2+0x52/0x52
[   53.122576]  ? vprintk_func+0x81/0x117
[   53.126500]  print_circular_bug.isra.34.cold.55+0x1bd/0x27d
[   53.132268]  ? save_trace+0xe0/0x290
[   53.135973]  __lock_acquire+0x3449/0x5020
[   53.140109]  ? mark_held_locks+0x160/0x160
[   53.144325]  ? find_held_lock+0x36/0x1c0
[   53.148369]  ? mark_held_locks+0xc9/0x160
[   53.152504]  ? _raw_spin_unlock_irqrestore+0x74/0xc0
[   53.157593]  ? _raw_spin_unlock_irqrestore+0x74/0xc0
[   53.162678]  ? lockdep_hardirqs_on+0x421/0x5c0
[   53.167240]  ? trace_hardirqs_on+0xbd/0x2c0
[   53.171544]  ? kasan_check_read+0x11/0x20
[   53.175672]  ? remove_wait_queue+0x1a6/0x360
[   53.180060]  ? trace_hardirqs_off_caller+0x2b0/0x2b0
[   53.185143]  ? kasan_check_write+0x14/0x20
[   53.189359]  ? do_raw_spin_lock+0xc1/0x200
[   53.193582]  ? remove_wait_queue+0x1a6/0x360
[   53.198072]  ? graph_lock+0x170/0x170
[   53.201854]  ? add_wait_queue+0x2b0/0x2b0
[   53.205988]  lock_acquire+0x1e4/0x4f0
[   53.209779]  ? __might_fault+0xfb/0x1e0
[   53.213745]  ? lock_release+0x9f0/0x9f0
[   53.217842]  ? check_same_owner+0x340/0x340
[   53.222149]  ? __sanitizer_cov_trace_cmp8+0x18/0x20
[   53.227148]  ? __check_object_size+0xa3/0x5d7
[   53.231633]  __might_fault+0x155/0x1e0
[   53.235501]  ? __might_fault+0xfb/0x1e0
[   53.239459]  _copy_to_user+0x30/0x110
[   53.243241]  mon_bin_get_event+0x116/0x460
[   53.247458]  mon_bin_ioctl+0x459/0xe80
[   53.251328]  ? mon_bin_get_event+0x460/0x460
[   53.255718]  ? mon_bin_get_event+0x460/0x460
[   53.260112]  do_vfs_ioctl+0x1de/0x1720
[   53.263982]  ? ioctl_preallocate+0x300/0x300
[   53.268373]  ? __fget_light+0x2f7/0x440
[   53.272331]  ? fget_raw+0x20/0x20
[   53.275775]  ? _raw_spin_unlock_irq+0x27/0x70
[   53.280255]  ? do_syscall_64+0x9a/0x820
[   53.284259]  ? do_syscall_64+0x9a/0x820
[   53.288223]  ? lockdep_hardirqs_on+0x421/0x5c0
[   53.292802]  ? security_file_ioctl+0x94/0xc0
[   53.297201]  ksys_ioctl+0xa9/0xd0
[   53.300681]  __x64_sys_ioctl+0x73/0xb0
[   53.304557]  do_syscall_64+0x1b9/0x820
[   53.308476]  ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe
[   53.313826]  ? syscall_return_slowpath+0x5e0/0x5e0
[   53.318744]  ? trace_hardirqs_on_caller+0x2b0/0x2b0
[   53.323772]  ? prepare_exit_to_usermode+0x3b0/0x3b0
[   53.328783]  ? recalc_sigpending_tsk+0x180/0x180
[   53.333529]  ? kasan_check_write+0x14/0x20
[   53.337754]  ? trace_hardirqs_off_thunk+0x1a/0x1c
[   53.342593]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   53.347771] RIP: 0033:0x44a139
[   53.350947] Code: e8 6c b4 02 00 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 4b cd fb ff c3 66 2e 0f 1f 84 00 00 00 00
[   53.369829] RSP: 002b:00007fa6f2498da8 EFLAGS: 00000293 ORIG_RAX: 0000000000000010
[   53.377515] RAX: ffffffffffffffda RBX: 00000000006dbc68 RCX: 000000000044a139
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[   53.384780] RDX: 0000000020000000 RSI: 000000004018920a RDI: 0000000000000005
[   53.392042] RBP: 00000000006dbc60 R08: 00007fa6f2499700 R09: 0000000000000000
[   53.399292] R10: 00007fa6f2499700 R11: 0000000000000293 R12: 00000000006dbc6c
[   53.406539] R13: 6273752f7665642f R14: 7375622f7665642f R15: 00000000006dbd4c
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