[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 23.964036] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.031722] random: sshd: uninitialized urandom read (32 bytes read) [ 27.388104] random: sshd: uninitialized urandom read (32 bytes read) [ 27.972474] random: sshd: uninitialized urandom read (32 bytes read) [ 28.156019] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.12' (ECDSA) to the list of known hosts. [ 33.780179] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 33.883291] [ 33.884945] ====================================================== [ 33.891242] WARNING: possible circular locking dependency detected [ 33.897550] 4.19.0-rc1+ #217 Not tainted [ 33.901611] ------------------------------------------------------ [ 33.907926] syz-executor020/4642 is trying to acquire lock: [ 33.913618] 00000000c515bf7d (&rp->fetch_lock){+.+.}, at: mon_bin_vma_fault+0xdc/0x4a0 [ 33.921703] [ 33.921703] but task is already holding lock: [ 33.927705] 00000000ce83e5de (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 33.935324] [ 33.935324] which lock already depends on the new lock. [ 33.935324] [ 33.943746] [ 33.943746] the existing dependency chain (in reverse order) is: [ 33.951348] [ 33.951348] -> #1 (&mm->mmap_sem){++++}: [ 33.956887] __might_fault+0x155/0x1e0 [ 33.961289] _copy_to_user+0x30/0x110 [ 33.965605] mon_bin_read+0x334/0x650 [ 33.969934] __vfs_read+0x117/0x9b0 [ 33.974079] vfs_read+0x17f/0x3c0 [ 33.978041] ksys_pread64+0x181/0x1b0 [ 33.982348] __x64_sys_pread64+0x97/0xf0 [ 33.986918] do_syscall_64+0x1b9/0x820 [ 33.991336] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 33.997026] [ 33.997026] -> #0 (&rp->fetch_lock){+.+.}: [ 34.002733] lock_acquire+0x1e4/0x4f0 [ 34.007042] __mutex_lock+0x171/0x1700 [ 34.011435] mutex_lock_nested+0x16/0x20 [ 34.016003] mon_bin_vma_fault+0xdc/0x4a0 [ 34.020659] __do_fault+0xee/0x450 [ 34.024704] __handle_mm_fault+0x2b4a/0x4350 [ 34.029624] handle_mm_fault+0x53e/0xc80 [ 34.034208] __get_user_pages+0x823/0x1b50 [ 34.038947] populate_vma_page_range+0x2db/0x3d0 [ 34.044206] __mm_populate+0x286/0x4d0 [ 34.048597] vm_mmap_pgoff+0x27f/0x2c0 [ 34.052987] ksys_mmap_pgoff+0x4da/0x660 [ 34.057562] __x64_sys_mmap+0xe9/0x1b0 [ 34.061975] do_syscall_64+0x1b9/0x820 [ 34.066379] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.072076] [ 34.072076] other info that might help us debug this: [ 34.072076] [ 34.080201] Possible unsafe locking scenario: [ 34.080201] [ 34.086261] CPU0 CPU1 [ 34.090909] ---- ---- [ 34.095557] lock(&mm->mmap_sem); [ 34.099080] lock(&rp->fetch_lock); [ 34.105291] lock(&mm->mmap_sem); [ 34.111330] lock(&rp->fetch_lock); [ 34.115024] [ 34.115024] *** DEADLOCK *** [ 34.115024] [ 34.121078] 1 lock held by syz-executor020/4642: [ 34.125811] #0: 00000000ce83e5de (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 34.133870] [ 34.133870] stack backtrace: [ 34.138371] CPU: 1 PID: 4642 Comm: syz-executor020 Not tainted 4.19.0-rc1+ #217 [ 34.145797] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.155132] Call Trace: [ 34.157724] dump_stack+0x1c9/0x2b4 [ 34.161352] ? dump_stack_print_info.cold.2+0x52/0x52 [ 34.166529] ? vprintk_func+0x81/0x117 [ 34.170412] print_circular_bug.isra.34.cold.55+0x1bd/0x27d [ 34.176108] ? save_trace+0xe0/0x290 [ 34.179807] __lock_acquire+0x3449/0x5020 [ 34.183941] ? __isolate_free_page+0x690/0x690 [ 34.188511] ? mark_held_locks+0x160/0x160 [ 34.192886] ? print_usage_bug+0xc0/0xc0 [ 34.196932] ? free_unref_page_list+0xbca/0x11a0 [ 34.201674] ? __lock_acquire+0x7fc/0x5020 [ 34.205899] ? print_usage_bug+0xc0/0xc0 [ 34.209948] ? mark_held_locks+0x160/0x160 [ 34.214167] ? __lock_acquire+0x7fc/0x5020 [ 34.218386] ? mark_held_locks+0x160/0x160 [ 34.222608] ? mark_held_locks+0x160/0x160 [ 34.226824] ? graph_lock+0x170/0x170 [ 34.230610] ? mark_held_locks+0x160/0x160 [ 34.234825] ? print_usage_bug+0xc0/0xc0 [ 34.238872] lock_acquire+0x1e4/0x4f0 [ 34.242680] ? mon_bin_vma_fault+0xdc/0x4a0 [ 34.246985] ? lock_release+0x9f0/0x9f0 [ 34.250947] ? check_same_owner+0x340/0x340 [ 34.255254] ? rcu_note_context_switch+0x680/0x680 [ 34.260172] __mutex_lock+0x171/0x1700 [ 34.264049] ? mon_bin_vma_fault+0xdc/0x4a0 [ 34.268356] ? mon_bin_vma_fault+0xdc/0x4a0 [ 34.272668] ? mutex_trylock+0x2b0/0x2b0 [ 34.276713] ? mark_held_locks+0x160/0x160 [ 34.280932] ? lock_downgrade+0x8f0/0x8f0 [ 34.285064] ? trace_hardirqs_off+0xb8/0x2b0 [ 34.289459] ? kasan_check_read+0x11/0x20 [ 34.293603] ? print_usage_bug+0xc0/0xc0 [ 34.297668] ? trace_hardirqs_on+0x2c0/0x2c0 [ 34.302065] ? kasan_check_write+0x14/0x20 [ 34.306286] ? do_raw_spin_lock+0xc1/0x200 [ 34.310508] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 34.315598] ? print_usage_bug+0xc0/0xc0 [ 34.319646] ? graph_lock+0x170/0x170 [ 34.323431] ? print_usage_bug+0xc0/0xc0 [ 34.327480] ? __lock_acquire+0x7fc/0x5020 [ 34.331736] ? graph_lock+0x170/0x170 [ 34.335527] ? kasan_slab_free+0xe/0x10 [ 34.339487] ? print_usage_bug+0xc0/0xc0 [ 34.343532] ? __lock_acquire+0x7fc/0x5020 [ 34.347754] mutex_lock_nested+0x16/0x20 [ 34.351803] ? mutex_lock_nested+0x16/0x20 [ 34.356024] mon_bin_vma_fault+0xdc/0x4a0 [ 34.360350] ? kasan_check_read+0x11/0x20 [ 34.364488] ? mon_alloc_buff+0x200/0x200 [ 34.368620] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 34.373281] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 34.378286] ? vma_compute_subtree_gap+0x160/0x240 [ 34.383202] ? vma_gap_callbacks_rotate+0x62/0x80 [ 34.388035] __do_fault+0xee/0x450 [ 34.391560] ? vma_compute_subtree_gap+0x240/0x240 [ 34.396498] ? pmd_devmap_trans_unstable+0x1d0/0x1d0 [ 34.401598] ? __save_stack_trace+0x8d/0xf0 [ 34.405920] ? pud_val+0x88/0x100 [ 34.409354] ? pmd_val+0x100/0x100 [ 34.412892] __handle_mm_fault+0x2b4a/0x4350 [ 34.417289] ? vmf_insert_mixed_mkwrite+0xa0/0xa0 [ 34.422113] ? graph_lock+0x170/0x170 [ 34.425906] ? lock_downgrade+0x8f0/0x8f0 [ 34.430041] ? handle_mm_fault+0x8c4/0xc80 [ 34.434291] ? handle_mm_fault+0x8c4/0xc80 [ 34.438522] ? kasan_check_read+0x11/0x20 [ 34.442659] ? rcu_is_watching+0x8c/0x150 [ 34.446791] ? __get_user_pages+0x823/0x1b50 [ 34.451185] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 34.455838] handle_mm_fault+0x53e/0xc80 [ 34.459890] ? __handle_mm_fault+0x4350/0x4350 [ 34.464458] ? check_same_owner+0x340/0x340 [ 34.468767] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 34.473769] __get_user_pages+0x823/0x1b50 [ 34.477994] ? follow_page_mask+0x1e30/0x1e30 [ 34.482502] ? lock_acquire+0x1e4/0x4f0 [ 34.486464] ? __mm_populate+0x31a/0x4d0 [ 34.490511] ? lock_release+0x9f0/0x9f0 [ 34.494470] ? check_same_owner+0x340/0x340 [ 34.498778] ? rcu_note_context_switch+0x680/0x680 [ 34.503720] populate_vma_page_range+0x2db/0x3d0 [ 34.508462] ? get_user_pages_unlocked+0x5d0/0x5d0 [ 34.513380] ? find_vma+0x34/0x190 [ 34.516909] __mm_populate+0x286/0x4d0 [ 34.520958] ? populate_vma_page_range+0x3d0/0x3d0 [ 34.525886] ? down_read_killable+0x200/0x200 [ 34.530369] ? security_mmap_file+0x176/0x1c0 [ 34.534849] vm_mmap_pgoff+0x27f/0x2c0 [ 34.538722] ? vma_is_stack_for_current+0xd0/0xd0 [ 34.543549] ? putname+0xf2/0x130 [ 34.546991] ? rcu_read_lock_sched_held+0x108/0x120 [ 34.551991] ksys_mmap_pgoff+0x4da/0x660 [ 34.556065] ? do_syscall_64+0x9a/0x820 [ 34.560025] ? find_mergeable_anon_vma+0xd0/0xd0 [ 34.564788] ? trace_hardirqs_on+0xbd/0x2c0 [ 34.569096] ? filp_open+0x80/0x80 [ 34.572621] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.577974] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 34.583066] __x64_sys_mmap+0xe9/0x1b0 [ 34.586941] do_syscall_64+0x1b9/0x820 [ 34.590813] ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe [ 34.596163] ? syscall_return_slowpath+0x5e0/0x5e0 [ 34.601078] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 34.605906] ? trace_hardirqs_on_caller+0x2b0/0x2b0 [ 34.610908] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 34.615911] ? prepare_exit_to_usermode+0x291/0x3b0 [ 34.620914] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 34.625746] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.630920] RIP: 0033:0x443df9 [ 34.634098] 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 [ 34.652987] RSP: 002b:00007ffe00ae0058 EFLAGS: 00000212 ORIG_RAX: 0000000000000009 [ 34.660680] RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443df9 [ 34.667934] RDX: 0000000001fffffd RSI: 0000000000400000 RDI: 0000000020a05000 [ 34.675190] RBP: 00000000006ce018 R08: 0000000000000005 R09: 0000000000000000 [ 34.682443] R10: 0000000000008011 R11: 000000000000