[....] Starting OpenBSD Secure Shell server: sshd[ 24.811966] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 29.836275] random: sshd: uninitialized urandom read (32 bytes read) [ 30.122987] sshd (4698) used greatest stack depth: 16840 bytes left [ 30.142015] random: sshd: uninitialized urandom read (32 bytes read) [ 30.708247] random: sshd: uninitialized urandom read (32 bytes read) [ 30.890308] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.53' (ECDSA) to the list of known hosts. [ 36.557505] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 36.661186] [ 36.662851] ====================================================== [ 36.669155] WARNING: possible circular locking dependency detected [ 36.675459] 4.19.0-rc1-next-20180831+ #53 Not tainted [ 36.680631] ------------------------------------------------------ [ 36.686937] syz-executor312/4715 is trying to acquire lock: [ 36.692642] 0000000073105829 (&rp->fetch_lock){+.+.}, at: mon_bin_vma_fault+0xdc/0x4a0 [ 36.700702] [ 36.700702] but task is already holding lock: [ 36.706656] 000000000adb36ed (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 36.714270] [ 36.714270] which lock already depends on the new lock. [ 36.714270] [ 36.722569] [ 36.722569] the existing dependency chain (in reverse order) is: [ 36.730175] [ 36.730175] -> #1 (&mm->mmap_sem){++++}: [ 36.735716] __might_fault+0x155/0x1e0 [ 36.740253] _copy_to_user+0x30/0x110 [ 36.744560] mon_bin_read+0x334/0x650 [ 36.748879] __vfs_read+0x117/0x9b0 [ 36.753013] vfs_read+0x17f/0x3c0 [ 36.756971] ksys_pread64+0x181/0x1b0 [ 36.761276] __x64_sys_pread64+0x97/0xf0 [ 36.765847] do_syscall_64+0x1b9/0x820 [ 36.770246] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 36.775963] [ 36.775963] -> #0 (&rp->fetch_lock){+.+.}: [ 36.781671] lock_acquire+0x1e4/0x4f0 [ 36.785974] __mutex_lock+0x171/0x1700 [ 36.790366] mutex_lock_nested+0x16/0x20 [ 36.794930] mon_bin_vma_fault+0xdc/0x4a0 [ 36.799579] __do_fault+0xee/0x450 [ 36.803624] __handle_mm_fault+0x13c6/0x4350 [ 36.808537] handle_mm_fault+0x53e/0xc80 [ 36.813106] __get_user_pages+0x823/0x1b50 [ 36.817846] populate_vma_page_range+0x2db/0x3d0 [ 36.823108] __mm_populate+0x286/0x4d0 [ 36.827504] vm_mmap_pgoff+0x27f/0x2c0 [ 36.831897] ksys_mmap_pgoff+0x4da/0x660 [ 36.836463] __x64_sys_mmap+0xe9/0x1b0 [ 36.840870] do_syscall_64+0x1b9/0x820 [ 36.845273] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 36.850983] [ 36.850983] other info that might help us debug this: [ 36.850983] [ 36.859107] Possible unsafe locking scenario: [ 36.859107] [ 36.865144] CPU0 CPU1 [ 36.869790] ---- ---- [ 36.874433] lock(&mm->mmap_sem); [ 36.877952] lock(&rp->fetch_lock); [ 36.884162] lock(&mm->mmap_sem); [ 36.890198] lock(&rp->fetch_lock); [ 36.893890] [ 36.893890] *** DEADLOCK *** [ 36.893890] [ 36.899933] 1 lock held by syz-executor312/4715: [ 36.904664] #0: 000000000adb36ed (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 36.912718] [ 36.912718] stack backtrace: [ 36.917199] CPU: 1 PID: 4715 Comm: syz-executor312 Not tainted 4.19.0-rc1-next-20180831+ #53 [ 36.925751] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 36.935083] Call Trace: [ 36.937659] dump_stack+0x1c9/0x2b4 [ 36.941279] ? dump_stack_print_info.cold.2+0x52/0x52 [ 36.946457] ? vprintk_func+0x81/0x117 [ 36.950333] print_circular_bug.isra.34.cold.55+0x1bd/0x27d [ 36.956029] ? save_trace+0xe0/0x290 [ 36.959724] __lock_acquire+0x3449/0x5020 [ 36.963853] ? __isolate_free_page+0x690/0x690 [ 36.968427] ? mark_held_locks+0x160/0x160 [ 36.972644] ? print_usage_bug+0xc0/0xc0 [ 36.976704] ? mark_held_locks+0x160/0x160 [ 36.980922] ? print_usage_bug+0xc0/0xc0 [ 36.984967] ? mark_held_locks+0x160/0x160 [ 36.989185] ? print_usage_bug+0xc0/0xc0 [ 36.993230] ? __lock_acquire+0x7fc/0x5020 [ 36.997448] ? mark_held_locks+0x160/0x160 [ 37.001666] ? print_usage_bug+0xc0/0xc0 [ 37.005708] ? graph_lock+0x170/0x170 [ 37.009520] lock_acquire+0x1e4/0x4f0 [ 37.013315] ? mon_bin_vma_fault+0xdc/0x4a0 [ 37.017619] ? lock_release+0x9f0/0x9f0 [ 37.021579] ? check_same_owner+0x340/0x340 [ 37.025903] ? __lock_acquire+0x7fc/0x5020 [ 37.030126] ? rcu_note_context_switch+0x680/0x680 [ 37.035044] __mutex_lock+0x171/0x1700 [ 37.038919] ? mon_bin_vma_fault+0xdc/0x4a0 [ 37.043223] ? mark_held_locks+0x160/0x160 [ 37.047443] ? mon_bin_vma_fault+0xdc/0x4a0 [ 37.051769] ? mutex_trylock+0x2b0/0x2b0 [ 37.055830] ? rb_insert_color_cached+0x14c0/0x14c0 [ 37.060839] ? kernel_text_address+0x79/0xf0 [ 37.065235] ? __kernel_text_address+0xd/0x40 [ 37.069716] ? unwind_get_return_address+0x61/0xa0 [ 37.074630] ? find_held_lock+0x36/0x1c0 [ 37.078681] ? __mem_cgroup_largest_soft_limit_node.part.64+0x7f0/0x7f0 [ 37.085433] ? lock_downgrade+0x8f0/0x8f0 [ 37.089568] ? kasan_check_read+0x11/0x20 [ 37.093701] ? rcu_is_watching+0x8c/0x150 [ 37.097834] ? graph_lock+0x170/0x170 [ 37.101628] ? get_mem_cgroup_from_mm+0x209/0x440 [ 37.106454] ? find_held_lock+0x36/0x1c0 [ 37.110505] mutex_lock_nested+0x16/0x20 [ 37.114551] ? mutex_lock_nested+0x16/0x20 [ 37.118770] mon_bin_vma_fault+0xdc/0x4a0 [ 37.122914] ? rcu_is_watching+0x8c/0x150 [ 37.127046] ? mon_alloc_buff+0x200/0x200 [ 37.131177] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 37.135840] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 37.141368] __do_fault+0xee/0x450 [ 37.144894] ? pmd_devmap_trans_unstable+0x1d0/0x1d0 [ 37.149984] ? __save_stack_trace+0x8d/0xf0 [ 37.154291] ? __sanitizer_cov_trace_const_cmp2+0x18/0x20 [ 37.159824] __handle_mm_fault+0x13c6/0x4350 [ 37.164222] ? vmf_insert_mixed_mkwrite+0xa0/0xa0 [ 37.169048] ? graph_lock+0x170/0x170 [ 37.172838] ? lock_downgrade+0x8f0/0x8f0 [ 37.176992] ? handle_mm_fault+0x8c4/0xc80 [ 37.181224] ? handle_mm_fault+0x8c4/0xc80 [ 37.185444] ? kasan_check_read+0x11/0x20 [ 37.189574] ? rcu_is_watching+0x8c/0x150 [ 37.193709] ? __get_user_pages+0x823/0x1b50 [ 37.198106] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 37.202763] handle_mm_fault+0x53e/0xc80 [ 37.206822] ? __handle_mm_fault+0x4350/0x4350 [ 37.211406] ? check_same_owner+0x340/0x340 [ 37.215732] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 37.220763] __get_user_pages+0x823/0x1b50 [ 37.224993] ? follow_page_mask+0x1e30/0x1e30 [ 37.229474] ? lock_acquire+0x1e4/0x4f0 [ 37.233433] ? __mm_populate+0x31a/0x4d0 [ 37.237477] ? lock_release+0x9f0/0x9f0 [ 37.241437] ? check_same_owner+0x340/0x340 [ 37.245743] ? rcu_note_context_switch+0x680/0x680 [ 37.250657] populate_vma_page_range+0x2db/0x3d0 [ 37.255398] ? get_user_pages_unlocked+0x5d0/0x5d0 [ 37.260316] ? find_vma+0x34/0x190 [ 37.263839] __mm_populate+0x286/0x4d0 [ 37.267719] ? populate_vma_page_range+0x3d0/0x3d0 [ 37.272632] ? down_read_killable+0x200/0x200 [ 37.277143] ? security_mmap_file+0x176/0x1c0 [ 37.281630] vm_mmap_pgoff+0x27f/0x2c0 [ 37.285502] ? vma_is_stack_for_current+0xd0/0xd0 [ 37.290326] ? putname+0xf2/0x130 [ 37.293765] ? rcu_read_lock_sched_held+0x108/0x120 [ 37.298776] ksys_mmap_pgoff+0x4da/0x660 [ 37.302841] ? do_syscall_64+0x9a/0x820 [ 37.306824] ? find_mergeable_anon_vma+0xd0/0xd0 [ 37.311565] ? trace_hardirqs_on+0xbd/0x2c0 [ 37.315873] ? filp_open+0x80/0x80 [ 37.319400] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 37.324748] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 37.329837] __x64_sys_mmap+0xe9/0x1b0 [ 37.333718] do_syscall_64+0x1b9/0x820 [ 37.337593] ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe [ 37.342940] ? syscall_return_slowpath+0x5e0/0x5e0 [ 37.347859] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 37.352688] ? trace_hardirqs_on_caller+0x2b0/0x2b0 [ 37.357697] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 37.362696] ? prepare_exit_to_usermode+0x291/0x3b0 [ 37.367702] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 37.372532] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 37.377726] RIP: 0033:0x443df9 [ 37.380906] 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 [ 37.399825] RSP: 002b:00007ffdf8dec348 EFLAGS: 00000212 ORIG_RAX: 0000000000000009 [ 37.407541] RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443df9