[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 23.757884] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 29.371610] random: sshd: uninitialized urandom read (32 bytes read) [ 29.681024] random: sshd: uninitialized urandom read (32 bytes read) [ 30.246197] random: sshd: uninitialized urandom read (32 bytes read) [ 34.557217] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.53' (ECDSA) to the list of known hosts. [ 40.163080] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 40.264279] [ 40.265917] ====================================================== [ 40.272211] WARNING: possible circular locking dependency detected [ 40.278506] 4.19.0-rc1+ #120 Not tainted [ 40.282543] ------------------------------------------------------ [ 40.288859] syz-executor621/4662 is trying to acquire lock: [ 40.294547] 00000000f709ba4c (&rp->fetch_lock){+.+.}, at: mon_bin_vma_fault+0xdc/0x4a0 [ 40.302600] [ 40.302600] but task is already holding lock: [ 40.308551] 000000004412c2cf (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 40.316167] [ 40.316167] which lock already depends on the new lock. [ 40.316167] [ 40.324462] [ 40.324462] the existing dependency chain (in reverse order) is: [ 40.332077] [ 40.332077] -> #1 (&mm->mmap_sem){++++}: [ 40.337608] __might_fault+0x155/0x1e0 [ 40.342000] _copy_to_user+0x30/0x110 [ 40.346307] mon_bin_read+0x334/0x650 [ 40.350612] __vfs_read+0x117/0x9b0 [ 40.354744] vfs_read+0x17f/0x3c0 [ 40.358715] ksys_pread64+0x181/0x1b0 [ 40.363020] __ia32_compat_sys_x86_pread+0xc4/0x130 [ 40.368540] do_fast_syscall_32+0x34d/0xfb2 [ 40.373377] entry_SYSENTER_compat+0x70/0x7f [ 40.378282] [ 40.378282] -> #0 (&rp->fetch_lock){+.+.}: [ 40.383986] lock_acquire+0x1e4/0x4f0 [ 40.388292] __mutex_lock+0x171/0x1700 [ 40.392694] mutex_lock_nested+0x16/0x20 [ 40.397258] mon_bin_vma_fault+0xdc/0x4a0 [ 40.401908] __do_fault+0xee/0x450 [ 40.405953] __handle_mm_fault+0x13c6/0x4350 [ 40.410864] handle_mm_fault+0x53e/0xc80 [ 40.415445] __get_user_pages+0x823/0x1b50 [ 40.420189] populate_vma_page_range+0x2db/0x3d0 [ 40.425450] __mm_populate+0x286/0x4d0 [ 40.429849] vm_mmap_pgoff+0x27f/0x2c0 [ 40.434240] ksys_mmap_pgoff+0x4da/0x660 [ 40.438805] __ia32_sys_mmap_pgoff+0xdd/0x1a0 [ 40.443805] do_fast_syscall_32+0x34d/0xfb2 [ 40.448941] entry_SYSENTER_compat+0x70/0x7f [ 40.453850] [ 40.453850] other info that might help us debug this: [ 40.453850] [ 40.461994] Possible unsafe locking scenario: [ 40.461994] [ 40.468035] CPU0 CPU1 [ 40.472679] ---- ---- [ 40.477324] lock(&mm->mmap_sem); [ 40.480848] lock(&rp->fetch_lock); [ 40.487068] lock(&mm->mmap_sem); [ 40.493103] lock(&rp->fetch_lock); [ 40.496796] [ 40.496796] *** DEADLOCK *** [ 40.496796] [ 40.502839] 1 lock held by syz-executor621/4662: [ 40.507568] #0: 000000004412c2cf (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 40.515619] [ 40.515619] stack backtrace: [ 40.520123] CPU: 0 PID: 4662 Comm: syz-executor621 Not tainted 4.19.0-rc1+ #120 [ 40.527549] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 40.536883] Call Trace: [ 40.539461] dump_stack+0x1c9/0x2b4 [ 40.543096] ? dump_stack_print_info.cold.2+0x52/0x52 [ 40.548271] ? vprintk_func+0x81/0x117 [ 40.552254] print_circular_bug.isra.34.cold.55+0x1bd/0x27d [ 40.557951] ? save_trace+0xe0/0x290 [ 40.561647] __lock_acquire+0x3449/0x5020 [ 40.565798] ? __isolate_free_page+0x690/0x690 [ 40.570366] ? mark_held_locks+0x160/0x160 [ 40.574584] ? print_usage_bug+0xc0/0xc0 [ 40.578631] ? mark_held_locks+0x160/0x160 [ 40.582847] ? print_usage_bug+0xc0/0xc0 [ 40.586908] ? print_usage_bug+0xc0/0xc0 [ 40.590970] ? mark_held_locks+0x160/0x160 [ 40.595190] ? print_usage_bug+0xc0/0xc0 [ 40.599233] ? graph_lock+0x170/0x170 [ 40.603019] lock_acquire+0x1e4/0x4f0 [ 40.606843] ? mon_bin_vma_fault+0xdc/0x4a0 [ 40.611149] ? lock_release+0x9f0/0x9f0 [ 40.615106] ? check_same_owner+0x340/0x340 [ 40.619410] ? __lock_acquire+0x7fc/0x5020 [ 40.623629] ? rcu_note_context_switch+0x680/0x680 [ 40.628547] __mutex_lock+0x171/0x1700 [ 40.632419] ? mon_bin_vma_fault+0xdc/0x4a0 [ 40.636724] ? mark_held_locks+0x160/0x160 [ 40.640945] ? mark_held_locks+0xc9/0x160 [ 40.645116] ? mon_bin_vma_fault+0xdc/0x4a0 [ 40.649423] ? mutex_trylock+0x2b0/0x2b0 [ 40.653478] ? rb_insert_color_cached+0x14c0/0x14c0 [ 40.658513] ? depot_save_stack+0x291/0x470 [ 40.662820] ? kasan_check_write+0x14/0x20 [ 40.667036] ? find_held_lock+0x36/0x1c0 [ 40.671087] ? __mem_cgroup_largest_soft_limit_node.part.64+0x7f0/0x7f0 [ 40.677821] ? lock_downgrade+0x8f0/0x8f0 [ 40.681952] ? kasan_check_read+0x11/0x20 [ 40.686083] ? rcu_is_watching+0x8c/0x150 [ 40.690211] ? graph_lock+0x170/0x170 [ 40.693997] ? get_mem_cgroup_from_mm+0x209/0x440 [ 40.698824] ? find_held_lock+0x36/0x1c0 [ 40.702871] mutex_lock_nested+0x16/0x20 [ 40.706918] ? mutex_lock_nested+0x16/0x20 [ 40.711135] mon_bin_vma_fault+0xdc/0x4a0 [ 40.715268] ? rcu_is_watching+0x8c/0x150 [ 40.719403] ? mon_alloc_buff+0x200/0x200 [ 40.723537] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 40.728195] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 40.733716] __do_fault+0xee/0x450 [ 40.737260] ? pmd_devmap_trans_unstable+0x1d0/0x1d0 [ 40.742369] ? __sanitizer_cov_trace_const_cmp2+0x18/0x20 [ 40.747893] __handle_mm_fault+0x13c6/0x4350 [ 40.752288] ? vmf_insert_mixed_mkwrite+0xa0/0xa0 [ 40.757135] ? graph_lock+0x170/0x170 [ 40.760925] ? lock_downgrade+0x8f0/0x8f0 [ 40.765056] ? handle_mm_fault+0x8c4/0xc80 [ 40.769316] ? handle_mm_fault+0x8c4/0xc80 [ 40.773535] ? kasan_check_read+0x11/0x20 [ 40.777673] ? rcu_is_watching+0x8c/0x150 [ 40.781810] ? __get_user_pages+0x823/0x1b50 [ 40.786211] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 40.790867] handle_mm_fault+0x53e/0xc80 [ 40.794911] ? __handle_mm_fault+0x4350/0x4350 [ 40.799489] ? check_same_owner+0x340/0x340 [ 40.803800] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 40.808808] __get_user_pages+0x823/0x1b50 [ 40.813028] ? follow_page_mask+0x1e30/0x1e30 [ 40.817514] ? lock_acquire+0x1e4/0x4f0 [ 40.821510] ? __mm_populate+0x31a/0x4d0 [ 40.825557] ? lock_release+0x9f0/0x9f0 [ 40.829517] ? check_same_owner+0x340/0x340 [ 40.833821] ? rcu_note_context_switch+0x680/0x680 [ 40.838736] populate_vma_page_range+0x2db/0x3d0 [ 40.843499] ? get_user_pages_unlocked+0x5d0/0x5d0 [ 40.848415] ? find_vma+0x34/0x190 [ 40.851941] __mm_populate+0x286/0x4d0 [ 40.855814] ? populate_vma_page_range+0x3d0/0x3d0 [ 40.860745] ? down_read_killable+0x200/0x200 [ 40.865238] ? security_mmap_file+0x176/0x1c0 [ 40.869720] vm_mmap_pgoff+0x27f/0x2c0 [ 40.873596] ? vma_is_stack_for_current+0xd0/0xd0 [ 40.878435] ? putname+0xf2/0x130 [ 40.881892] ? rcu_read_lock_sched_held+0x108/0x120 [ 40.886894] ksys_mmap_pgoff+0x4da/0x660 [ 40.890940] ? do_fast_syscall_32+0x150/0xfb2 [ 40.895418] ? find_mergeable_anon_vma+0xd0/0xd0 [ 40.900156] ? trace_hardirqs_on+0xbd/0x2c0 [ 40.904478] ? filp_open+0x80/0x80 [ 40.908013] ? entry_SYSENTER_compat+0x70/0x7f [ 40.912580] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 40.917683] __ia32_sys_mmap_pgoff+0xdd/0x1a0 [ 40.922166] do_fast_syscall_32+0x34d/0xfb2 [ 40.926479] ? do_int80_syscall_32+0x890/0x890 [ 40.931054] ? entry_SYSENTER_compat+0x68/0x7f [ 40.935618] ? trace_hardirqs_off_caller+0xbb/0x2b0 [ 40.940617] ? syscall_return_slowpath+0x5e0/0x5e0 [ 40.945530] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 40.950353] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 40.955177] ? trace_hardirqs_on_caller+0x2b0/0x2b0 [ 40.960188] ? prepare_exit_to_usermode+0x291/0x3b0 [ 40.965188] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 40.970014] entry_SYSENTER_compat+0x70/0x7f [ 40.974408] RIP: 0023:0xf7f16ca9 [ 40.977766] Code: 55 08 8b 88 64 cd ff ff 8b 98 68 cd ff ff 89 c8 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 1c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 [ 40.996676] RSP: 002b:00000000ffe5575c EFLAGS: 00000296 ORIG_RAX: 00000000000000c0 [ 41.004365] RAX: ffffffffffffffda RBX: 0000000020e00000 RCX: 0000000000200000 [ 41.011616] RDX: 00000000000000ff RSI: 0000000000008012 RDI: 00000