[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 21.257167] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 24.631619] random: sshd: uninitialized urandom read (32 bytes read) [ 24.817602] random: sshd: uninitialized urandom read (32 bytes read) [ 25.368429] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.35' (ECDSA) to the list of known hosts. [ 31.314650] urandom_read: 1 callbacks suppressed [ 31.314655] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 31.415003] [ 31.416624] ====================================================== [ 31.422935] WARNING: possible circular locking dependency detected [ 31.429243] 4.19.0-rc1+ #217 Not tainted [ 31.433307] ------------------------------------------------------ [ 31.439608] syz-executor060/4573 is trying to acquire lock: [ 31.445290] 0000000074650bbe (&rp->fetch_lock){+.+.}, at: mon_bin_vma_fault+0xdc/0x4a0 [ 31.453353] [ 31.453353] but task is already holding lock: [ 31.459304] 000000007ac4b314 (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 31.466937] [ 31.466937] which lock already depends on the new lock. [ 31.466937] [ 31.475243] [ 31.475243] the existing dependency chain (in reverse order) is: [ 31.482837] [ 31.482837] -> #1 (&mm->mmap_sem){++++}: [ 31.488377] __might_fault+0x155/0x1e0 [ 31.492763] _copy_to_user+0x30/0x110 [ 31.497077] mon_bin_read+0x334/0x650 [ 31.501376] __vfs_read+0x117/0x9b0 [ 31.505515] vfs_read+0x17f/0x3c0 [ 31.509464] ksys_pread64+0x181/0x1b0 [ 31.513763] __x64_sys_pread64+0x97/0xf0 [ 31.518356] do_syscall_64+0x1b9/0x820 [ 31.522761] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 31.528442] [ 31.528442] -> #0 (&rp->fetch_lock){+.+.}: [ 31.534141] lock_acquire+0x1e4/0x4f0 [ 31.538442] __mutex_lock+0x171/0x1700 [ 31.542835] mutex_lock_nested+0x16/0x20 [ 31.547396] mon_bin_vma_fault+0xdc/0x4a0 [ 31.552041] __do_fault+0xee/0x450 [ 31.556080] __handle_mm_fault+0x13c6/0x4350 [ 31.561017] handle_mm_fault+0x53e/0xc80 [ 31.565582] __get_user_pages+0x823/0x1b50 [ 31.570339] populate_vma_page_range+0x2db/0x3d0 [ 31.575601] __mm_populate+0x286/0x4d0 [ 31.580000] vm_mmap_pgoff+0x27f/0x2c0 [ 31.584389] ksys_mmap_pgoff+0x4da/0x660 [ 31.588959] __x64_sys_mmap+0xe9/0x1b0 [ 31.593348] do_syscall_64+0x1b9/0x820 [ 31.597752] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 31.603431] [ 31.603431] other info that might help us debug this: [ 31.603431] [ 31.611546] Possible unsafe locking scenario: [ 31.611546] [ 31.617575] CPU0 CPU1 [ 31.622246] ---- ---- [ 31.626883] lock(&mm->mmap_sem); [ 31.630396] lock(&rp->fetch_lock); [ 31.636626] lock(&mm->mmap_sem); [ 31.642656] lock(&rp->fetch_lock); [ 31.646355] [ 31.646355] *** DEADLOCK *** [ 31.646355] [ 31.652404] 1 lock held by syz-executor060/4573: [ 31.657129] #0: 000000007ac4b314 (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 31.665192] [ 31.665192] stack backtrace: [ 31.669674] CPU: 0 PID: 4573 Comm: syz-executor060 Not tainted 4.19.0-rc1+ #217 [ 31.677094] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.686453] Call Trace: [ 31.689037] dump_stack+0x1c9/0x2b4 [ 31.692642] ? dump_stack_print_info.cold.2+0x52/0x52 [ 31.697812] ? vprintk_func+0x81/0x117 [ 31.701711] print_circular_bug.isra.34.cold.55+0x1bd/0x27d [ 31.707400] ? save_trace+0xe0/0x290 [ 31.711094] __lock_acquire+0x3449/0x5020 [ 31.715222] ? __isolate_free_page+0x690/0x690 [ 31.719781] ? mark_held_locks+0x160/0x160 [ 31.724005] ? print_usage_bug+0xc0/0xc0 [ 31.728043] ? mark_held_locks+0x160/0x160 [ 31.732252] ? print_usage_bug+0xc0/0xc0 [ 31.736307] ? mark_held_locks+0x160/0x160 [ 31.740535] ? print_usage_bug+0xc0/0xc0 [ 31.744575] ? __lock_acquire+0x7fc/0x5020 [ 31.748787] ? mark_held_locks+0x160/0x160 [ 31.753014] ? print_usage_bug+0xc0/0xc0 [ 31.757072] ? graph_lock+0x170/0x170 [ 31.760855] lock_acquire+0x1e4/0x4f0 [ 31.764633] ? mon_bin_vma_fault+0xdc/0x4a0 [ 31.768930] ? lock_release+0x9f0/0x9f0 [ 31.772885] ? check_same_owner+0x340/0x340 [ 31.777215] ? __lock_acquire+0x7fc/0x5020 [ 31.781430] ? rcu_note_context_switch+0x680/0x680 [ 31.786343] __mutex_lock+0x171/0x1700 [ 31.790210] ? mon_bin_vma_fault+0xdc/0x4a0 [ 31.794530] ? mark_held_locks+0x160/0x160 [ 31.798767] ? mon_bin_vma_fault+0xdc/0x4a0 [ 31.803067] ? mutex_trylock+0x2b0/0x2b0 [ 31.807125] ? rb_insert_color_cached+0x14c0/0x14c0 [ 31.812118] ? kernel_text_address+0x79/0xf0 [ 31.816504] ? __kernel_text_address+0xd/0x40 [ 31.821053] ? unwind_get_return_address+0x61/0xa0 [ 31.825962] ? find_held_lock+0x36/0x1c0 [ 31.830003] ? __mem_cgroup_largest_soft_limit_node.part.64+0x7f0/0x7f0 [ 31.836730] ? lock_downgrade+0x8f0/0x8f0 [ 31.840869] ? kasan_check_read+0x11/0x20 [ 31.844994] ? rcu_is_watching+0x8c/0x150 [ 31.849117] ? graph_lock+0x170/0x170 [ 31.852899] ? get_mem_cgroup_from_mm+0x209/0x440 [ 31.857737] ? find_held_lock+0x36/0x1c0 [ 31.861798] mutex_lock_nested+0x16/0x20 [ 31.865848] ? mutex_lock_nested+0x16/0x20 [ 31.870073] mon_bin_vma_fault+0xdc/0x4a0 [ 31.874203] ? rcu_is_watching+0x8c/0x150 [ 31.878330] ? mon_alloc_buff+0x200/0x200 [ 31.882470] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 31.887132] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 31.892696] __do_fault+0xee/0x450 [ 31.896217] ? pmd_devmap_trans_unstable+0x1d0/0x1d0 [ 31.901302] ? __save_stack_trace+0x8d/0xf0 [ 31.905605] ? __sanitizer_cov_trace_const_cmp2+0x18/0x20 [ 31.911121] __handle_mm_fault+0x13c6/0x4350 [ 31.915517] ? vmf_insert_mixed_mkwrite+0xa0/0xa0 [ 31.920365] ? graph_lock+0x170/0x170 [ 31.924148] ? lock_downgrade+0x8f0/0x8f0 [ 31.928272] ? handle_mm_fault+0x8c4/0xc80 [ 31.932485] ? handle_mm_fault+0x8c4/0xc80 [ 31.936696] ? kasan_check_read+0x11/0x20 [ 31.940820] ? rcu_is_watching+0x8c/0x150 [ 31.944945] ? __get_user_pages+0x823/0x1b50 [ 31.949340] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 31.953989] handle_mm_fault+0x53e/0xc80 [ 31.958040] ? __handle_mm_fault+0x4350/0x4350 [ 31.962601] ? check_same_owner+0x340/0x340 [ 31.966918] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 31.971916] __get_user_pages+0x823/0x1b50 [ 31.976134] ? follow_page_mask+0x1e30/0x1e30 [ 31.980611] ? lock_acquire+0x1e4/0x4f0 [ 31.984565] ? __mm_populate+0x31a/0x4d0 [ 31.988609] ? lock_release+0x9f0/0x9f0 [ 31.992578] ? check_same_owner+0x340/0x340 [ 31.996877] ? rcu_note_context_switch+0x680/0x680 [ 32.001787] populate_vma_page_range+0x2db/0x3d0 [ 32.006531] ? get_user_pages_unlocked+0x5d0/0x5d0 [ 32.011457] ? find_vma+0x34/0x190 [ 32.015004] __mm_populate+0x286/0x4d0 [ 32.018871] ? populate_vma_page_range+0x3d0/0x3d0 [ 32.023776] ? down_read_killable+0x200/0x200 [ 32.028252] ? security_mmap_file+0x176/0x1c0 [ 32.032741] vm_mmap_pgoff+0x27f/0x2c0 [ 32.036606] ? vma_is_stack_for_current+0xd0/0xd0 [ 32.041442] ? putname+0xf2/0x130 [ 32.044877] ? rcu_read_lock_sched_held+0x108/0x120 [ 32.049871] ksys_mmap_pgoff+0x4da/0x660 [ 32.053911] ? do_syscall_64+0x9a/0x820 [ 32.057865] ? find_mergeable_anon_vma+0xd0/0xd0 [ 32.062599] ? trace_hardirqs_on+0xbd/0x2c0 [ 32.066896] ? filp_open+0x80/0x80 [ 32.070425] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 32.075765] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 32.080849] __x64_sys_mmap+0xe9/0x1b0 [ 32.084713] do_syscall_64+0x1b9/0x820 [ 32.088592] ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe [ 32.093931] ? syscall_return_slowpath+0x5e0/0x5e0 [ 32.098835] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 32.103667] ? trace_hardirqs_on_caller+0x2b0/0x2b0 [ 32.108678] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 32.113672] ? prepare_exit_to_usermode+0x291/0x3b0 [ 32.118670] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 32.123490] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 32.128658] RIP: 0033:0x443df9 [ 32.131848] 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 [ 32.150723] RSP: 002b:00007ffcefb123e8 EFLAGS: 00000212 ORIG_RAX: 0000000000000009 [ 32.158451] RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443df9 [ 32.165704] RDX: 40000000000