[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 23.439431] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.939173] random: sshd: uninitialized urandom read (32 bytes read) [ 28.187142] random: sshd: uninitialized urandom read (32 bytes read) [ 28.761991] random: sshd: uninitialized urandom read (32 bytes read) [ 28.943186] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.8' (ECDSA) to the list of known hosts. [ 34.491108] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 34.595947] [ 34.597781] ====================================================== [ 34.604236] WARNING: possible circular locking dependency detected [ 34.610882] 4.19.0-rc1-next-20180831+ #53 Not tainted [ 34.616065] ------------------------------------------------------ [ 34.622374] syz-executor362/4663 is trying to acquire lock: [ 34.628196] 000000006381e192 (&rp->fetch_lock){+.+.}, at: mon_bin_vma_fault+0xdc/0x4a0 [ 34.636440] [ 34.636440] but task is already holding lock: [ 34.642529] 00000000130b5f93 (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 34.650308] [ 34.650308] which lock already depends on the new lock. [ 34.650308] [ 34.658910] [ 34.658910] the existing dependency chain (in reverse order) is: [ 34.666687] [ 34.666687] -> #1 (&mm->mmap_sem){++++}: [ 34.672242] __might_fault+0x155/0x1e0 [ 34.676647] _copy_to_user+0x30/0x110 [ 34.680964] mon_bin_read+0x334/0x650 [ 34.685611] __vfs_read+0x117/0x9b0 [ 34.689916] vfs_read+0x17f/0x3c0 [ 34.694138] ksys_pread64+0x181/0x1b0 [ 34.698457] __x64_sys_pread64+0x97/0xf0 [ 34.703135] do_syscall_64+0x1b9/0x820 [ 34.707551] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.713419] [ 34.713419] -> #0 (&rp->fetch_lock){+.+.}: [ 34.719350] lock_acquire+0x1e4/0x4f0 [ 34.723959] __mutex_lock+0x171/0x1700 [ 34.728361] mutex_lock_nested+0x16/0x20 [ 34.733070] mon_bin_vma_fault+0xdc/0x4a0 [ 34.737955] __do_fault+0xee/0x450 [ 34.742023] __handle_mm_fault+0x2b4a/0x4350 [ 34.747649] handle_mm_fault+0x53e/0xc80 [ 34.752471] __get_user_pages+0x823/0x1b50 [ 34.757490] populate_vma_page_range+0x2db/0x3d0 [ 34.763502] __mm_populate+0x286/0x4d0 [ 34.768059] vm_mmap_pgoff+0x27f/0x2c0 [ 34.772788] ksys_mmap_pgoff+0x4da/0x660 [ 34.777469] __x64_sys_mmap+0xe9/0x1b0 [ 34.782179] do_syscall_64+0x1b9/0x820 [ 34.786734] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.792580] [ 34.792580] other info that might help us debug this: [ 34.792580] [ 34.800811] Possible unsafe locking scenario: [ 34.800811] [ 34.807071] CPU0 CPU1 [ 34.811908] ---- ---- [ 34.816688] lock(&mm->mmap_sem); [ 34.820486] lock(&rp->fetch_lock); [ 34.826954] lock(&mm->mmap_sem); [ 34.833298] lock(&rp->fetch_lock); [ 34.837120] [ 34.837120] *** DEADLOCK *** [ 34.837120] [ 34.843263] 1 lock held by syz-executor362/4663: [ 34.848119] #0: 00000000130b5f93 (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 34.856345] [ 34.856345] stack backtrace: [ 34.861108] CPU: 0 PID: 4663 Comm: syz-executor362 Not tainted 4.19.0-rc1-next-20180831+ #53 [ 34.869816] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.879297] Call Trace: [ 34.882171] dump_stack+0x1c9/0x2b4 [ 34.885935] ? dump_stack_print_info.cold.2+0x52/0x52 [ 34.891309] ? vprintk_func+0x81/0x117 [ 34.895376] print_circular_bug.isra.34.cold.55+0x1bd/0x27d [ 34.901259] ? save_trace+0xe0/0x290 [ 34.905089] __lock_acquire+0x3449/0x5020 [ 34.909231] ? __isolate_free_page+0x690/0x690 [ 34.913811] ? mark_held_locks+0x160/0x160 [ 34.918038] ? print_usage_bug+0xc0/0xc0 [ 34.922234] ? free_unref_page_list+0xbca/0x11a0 [ 34.926987] ? __lock_acquire+0x7fc/0x5020 [ 34.931213] ? print_usage_bug+0xc0/0xc0 [ 34.935408] ? mark_held_locks+0x160/0x160 [ 34.939891] ? __lock_acquire+0x7fc/0x5020 [ 34.944276] ? mark_held_locks+0x160/0x160 [ 34.948534] ? mark_held_locks+0x160/0x160 [ 34.952762] ? graph_lock+0x170/0x170 [ 34.956556] ? mark_held_locks+0x160/0x160 [ 34.961070] ? print_usage_bug+0xc0/0xc0 [ 34.965144] lock_acquire+0x1e4/0x4f0 [ 34.968949] ? mon_bin_vma_fault+0xdc/0x4a0 [ 34.973432] ? lock_release+0x9f0/0x9f0 [ 34.977561] ? check_same_owner+0x340/0x340 [ 34.982020] ? rcu_note_context_switch+0x680/0x680 [ 34.987189] __mutex_lock+0x171/0x1700 [ 34.991515] ? mon_bin_vma_fault+0xdc/0x4a0 [ 34.996249] ? mon_bin_vma_fault+0xdc/0x4a0 [ 35.000705] ? mutex_trylock+0x2b0/0x2b0 [ 35.005026] ? mark_held_locks+0x160/0x160 [ 35.009683] ? lock_downgrade+0x8f0/0x8f0 [ 35.013833] ? trace_hardirqs_off+0xb8/0x2b0 [ 35.018265] ? kasan_check_read+0x11/0x20 [ 35.022461] ? print_usage_bug+0xc0/0xc0 [ 35.026519] ? trace_hardirqs_on+0x2c0/0x2c0 [ 35.031241] ? kasan_check_write+0x14/0x20 [ 35.035479] ? do_raw_spin_lock+0xc1/0x200 [ 35.039711] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 35.044810] ? print_usage_bug+0xc0/0xc0 [ 35.049100] ? graph_lock+0x170/0x170 [ 35.052903] ? print_usage_bug+0xc0/0xc0 [ 35.056956] ? __lock_acquire+0x7fc/0x5020 [ 35.061461] ? graph_lock+0x170/0x170 [ 35.065387] ? kasan_slab_free+0xe/0x10 [ 35.069523] ? print_usage_bug+0xc0/0xc0 [ 35.073579] ? __lock_acquire+0x7fc/0x5020 [ 35.077922] mutex_lock_nested+0x16/0x20 [ 35.081981] ? mutex_lock_nested+0x16/0x20 [ 35.086210] mon_bin_vma_fault+0xdc/0x4a0 [ 35.090353] ? kasan_check_read+0x11/0x20 [ 35.094493] ? mon_alloc_buff+0x200/0x200 [ 35.098633] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 35.103414] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 35.108708] ? vma_compute_subtree_gap+0x160/0x240 [ 35.113635] ? vma_gap_callbacks_rotate+0x62/0x80 [ 35.118609] __do_fault+0xee/0x450 [ 35.122145] ? vma_compute_subtree_gap+0x240/0x240 [ 35.127067] ? pmd_devmap_trans_unstable+0x1d0/0x1d0 [ 35.132278] ? __save_stack_trace+0x8d/0xf0 [ 35.136607] ? pud_val+0x88/0x100 [ 35.140053] ? pmd_val+0x100/0x100 [ 35.143720] __handle_mm_fault+0x2b4a/0x4350 [ 35.148246] ? vmf_insert_mixed_mkwrite+0xa0/0xa0 [ 35.153311] ? graph_lock+0x170/0x170 [ 35.157197] ? lock_downgrade+0x8f0/0x8f0 [ 35.161344] ? handle_mm_fault+0x8c4/0xc80 [ 35.165900] ? handle_mm_fault+0x8c4/0xc80 [ 35.170515] ? kasan_check_read+0x11/0x20 [ 35.174663] ? rcu_is_watching+0x8c/0x150 [ 35.179066] ? __get_user_pages+0x823/0x1b50 [ 35.183590] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 35.188389] handle_mm_fault+0x53e/0xc80 [ 35.192562] ? __handle_mm_fault+0x4350/0x4350 [ 35.197228] ? check_same_owner+0x340/0x340 [ 35.201896] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 35.207162] __get_user_pages+0x823/0x1b50 [ 35.211405] ? follow_page_mask+0x1e30/0x1e30 [ 35.216179] ? lock_acquire+0x1e4/0x4f0 [ 35.220296] ? __mm_populate+0x31a/0x4d0 [ 35.224509] ? lock_release+0x9f0/0x9f0 [ 35.228513] ? check_same_owner+0x340/0x340 [ 35.232956] ? rcu_note_context_switch+0x680/0x680 [ 35.237907] populate_vma_page_range+0x2db/0x3d0 [ 35.242776] ? get_user_pages_unlocked+0x5d0/0x5d0 [ 35.247818] ? find_vma+0x34/0x190 [ 35.251623] __mm_populate+0x286/0x4d0 [ 35.255517] ? populate_vma_page_range+0x3d0/0x3d0 [ 35.260459] ? down_read_killable+0x200/0x200 [ 35.265159] ? security_mmap_file+0x176/0x1c0 [ 35.269660] vm_mmap_pgoff+0x27f/0x2c0 [ 35.273679] ? vma_is_stack_for_current+0xd0/0xd0 [ 35.278813] ? putname+0xf2/0x130 [ 35.282409] ? rcu_read_lock_sched_held+0x108/0x120 [ 35.287420] ksys_mmap_pgoff+0x4da/0x660 [ 35.291480] ? do_syscall_64+0x9a/0x820 [ 35.295559] ? find_mergeable_anon_vma+0xd0/0xd0 [ 35.300314] ? trace_hardirqs_on+0xbd/0x2c0 [ 35.304753] ? filp_open+0x80/0x80 [ 35.308298] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 35.314038] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 35.319736] __x64_sys_mmap+0xe9/0x1b0 [ 35.323799] do_syscall_64+0x1b9/0x820 [ 35.327813] ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe [ 35.333284] ? syscall_return_slowpath+0x5e0/0x5e0 [ 35.338391] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 35.343232] ? trace_hardirqs_on_caller+0x2b0/0x2b0 [ 35.348427] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 35.353680] ? prepare_exit_to_usermode+0x291/0x3b0 [ 35.358695] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 35.363891] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 35.369079] RIP: 0033:0x443df9 [ 35.372429] Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 [ 35.391938] RSP: 002b:00007ffc6b76eac8 EFLAGS: 00000216 ORIG_RAX: 0000000000000009 [