[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 23.328082] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.764375] random: sshd: uninitialized urandom read (32 bytes read) [ 27.113711] random: sshd: uninitialized urandom read (32 bytes read) [ 27.662667] random: sshd: uninitialized urandom read (32 bytes read) [ 27.838863] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.56' (ECDSA) to the list of known hosts. [ 33.513524] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 33.610673] [ 33.612313] ====================================================== [ 33.618608] WARNING: possible circular locking dependency detected [ 33.624902] 4.19.0-rc1+ #217 Not tainted [ 33.628936] ------------------------------------------------------ [ 33.635229] syz-executor411/4673 is trying to acquire lock: [ 33.640931] 000000005c388dda (&rp->fetch_lock){+.+.}, at: mon_bin_vma_fault+0xdc/0x4a0 [ 33.648981] [ 33.648981] but task is already holding lock: [ 33.654951] 0000000017ec220b (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 33.662566] [ 33.662566] which lock already depends on the new lock. [ 33.662566] [ 33.670869] [ 33.670869] the existing dependency chain (in reverse order) is: [ 33.678470] [ 33.678470] -> #1 (&mm->mmap_sem){++++}: [ 33.684022] __might_fault+0x155/0x1e0 [ 33.688414] _copy_to_user+0x30/0x110 [ 33.692749] mon_bin_read+0x334/0x650 [ 33.697054] __vfs_read+0x117/0x9b0 [ 33.701181] vfs_read+0x17f/0x3c0 [ 33.705136] ksys_pread64+0x181/0x1b0 [ 33.709442] __x64_sys_pread64+0x97/0xf0 [ 33.714013] do_syscall_64+0x1b9/0x820 [ 33.718402] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 33.724084] [ 33.724084] -> #0 (&rp->fetch_lock){+.+.}: [ 33.729816] lock_acquire+0x1e4/0x4f0 [ 33.734122] __mutex_lock+0x171/0x1700 [ 33.738519] mutex_lock_nested+0x16/0x20 [ 33.743087] mon_bin_vma_fault+0xdc/0x4a0 [ 33.747734] __do_fault+0xee/0x450 [ 33.751777] __handle_mm_fault+0x13c6/0x4350 [ 33.756698] handle_mm_fault+0x53e/0xc80 [ 33.761264] __get_user_pages+0x823/0x1b50 [ 33.766000] populate_vma_page_range+0x2db/0x3d0 [ 33.771256] __mm_populate+0x286/0x4d0 [ 33.775645] vm_mmap_pgoff+0x27f/0x2c0 [ 33.780036] ksys_mmap_pgoff+0x4da/0x660 [ 33.784602] __x64_sys_mmap+0xe9/0x1b0 [ 33.788991] do_syscall_64+0x1b9/0x820 [ 33.793381] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 33.799078] [ 33.799078] other info that might help us debug this: [ 33.799078] [ 33.807196] Possible unsafe locking scenario: [ 33.807196] [ 33.813254] CPU0 CPU1 [ 33.817901] ---- ---- [ 33.822554] lock(&mm->mmap_sem); [ 33.826075] lock(&rp->fetch_lock); [ 33.832284] lock(&mm->mmap_sem); [ 33.838336] lock(&rp->fetch_lock); [ 33.842027] [ 33.842027] *** DEADLOCK *** [ 33.842027] [ 33.848068] 1 lock held by syz-executor411/4673: [ 33.852802] #0: 0000000017ec220b (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 33.860862] [ 33.860862] stack backtrace: [ 33.865343] CPU: 0 PID: 4673 Comm: syz-executor411 Not tainted 4.19.0-rc1+ #217 [ 33.872797] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.882135] Call Trace: [ 33.884712] dump_stack+0x1c9/0x2b4 [ 33.888323] ? dump_stack_print_info.cold.2+0x52/0x52 [ 33.893500] ? vprintk_func+0x81/0x117 [ 33.897371] print_circular_bug.isra.34.cold.55+0x1bd/0x27d [ 33.903066] ? save_trace+0xe0/0x290 [ 33.906766] __lock_acquire+0x3449/0x5020 [ 33.910905] ? __isolate_free_page+0x690/0x690 [ 33.915481] ? mark_held_locks+0x160/0x160 [ 33.919704] ? print_usage_bug+0xc0/0xc0 [ 33.923746] ? mark_held_locks+0x160/0x160 [ 33.928063] ? print_usage_bug+0xc0/0xc0 [ 33.932107] ? mark_held_locks+0x160/0x160 [ 33.936322] ? print_usage_bug+0xc0/0xc0 [ 33.940366] ? __lock_acquire+0x7fc/0x5020 [ 33.944581] ? mark_held_locks+0x160/0x160 [ 33.948802] ? print_usage_bug+0xc0/0xc0 [ 33.952852] ? graph_lock+0x170/0x170 [ 33.956635] lock_acquire+0x1e4/0x4f0 [ 33.960418] ? mon_bin_vma_fault+0xdc/0x4a0 [ 33.964722] ? lock_release+0x9f0/0x9f0 [ 33.968695] ? check_same_owner+0x340/0x340 [ 33.972999] ? __lock_acquire+0x7fc/0x5020 [ 33.977215] ? rcu_note_context_switch+0x680/0x680 [ 33.982128] __mutex_lock+0x171/0x1700 [ 33.985999] ? mon_bin_vma_fault+0xdc/0x4a0 [ 33.990301] ? mark_held_locks+0x160/0x160 [ 33.994522] ? mon_bin_vma_fault+0xdc/0x4a0 [ 33.998831] ? mutex_trylock+0x2b0/0x2b0 [ 34.002875] ? rb_insert_color_cached+0x14c0/0x14c0 [ 34.007870] ? kernel_text_address+0x79/0xf0 [ 34.012258] ? __kernel_text_address+0xd/0x40 [ 34.016735] ? unwind_get_return_address+0x61/0xa0 [ 34.021646] ? find_held_lock+0x36/0x1c0 [ 34.025711] ? __mem_cgroup_largest_soft_limit_node.part.64+0x7f0/0x7f0 [ 34.032468] ? lock_downgrade+0x8f0/0x8f0 [ 34.036607] ? kasan_check_read+0x11/0x20 [ 34.040753] ? rcu_is_watching+0x8c/0x150 [ 34.044883] ? graph_lock+0x170/0x170 [ 34.048700] ? get_mem_cgroup_from_mm+0x209/0x440 [ 34.053533] ? find_held_lock+0x36/0x1c0 [ 34.057577] mutex_lock_nested+0x16/0x20 [ 34.061636] ? mutex_lock_nested+0x16/0x20 [ 34.065871] mon_bin_vma_fault+0xdc/0x4a0 [ 34.070003] ? rcu_is_watching+0x8c/0x150 [ 34.074131] ? mon_alloc_buff+0x200/0x200 [ 34.078257] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 34.082911] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 34.088428] __do_fault+0xee/0x450 [ 34.091953] ? pmd_devmap_trans_unstable+0x1d0/0x1d0 [ 34.097042] ? __save_stack_trace+0x8d/0xf0 [ 34.101361] ? __sanitizer_cov_trace_const_cmp2+0x18/0x20 [ 34.106899] __handle_mm_fault+0x13c6/0x4350 [ 34.111289] ? vmf_insert_mixed_mkwrite+0xa0/0xa0 [ 34.116122] ? graph_lock+0x170/0x170 [ 34.119907] ? lock_downgrade+0x8f0/0x8f0 [ 34.124033] ? handle_mm_fault+0x8c4/0xc80 [ 34.128246] ? handle_mm_fault+0x8c4/0xc80 [ 34.132470] ? kasan_check_read+0x11/0x20 [ 34.136606] ? rcu_is_watching+0x8c/0x150 [ 34.140735] ? __get_user_pages+0x823/0x1b50 [ 34.145126] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 34.149776] handle_mm_fault+0x53e/0xc80 [ 34.153833] ? __handle_mm_fault+0x4350/0x4350 [ 34.158396] ? check_same_owner+0x340/0x340 [ 34.162703] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 34.167701] __get_user_pages+0x823/0x1b50 [ 34.171922] ? follow_page_mask+0x1e30/0x1e30 [ 34.176398] ? lock_acquire+0x1e4/0x4f0 [ 34.180393] ? __mm_populate+0x31a/0x4d0 [ 34.184433] ? lock_release+0x9f0/0x9f0 [ 34.188391] ? check_same_owner+0x340/0x340 [ 34.192708] ? rcu_note_context_switch+0x680/0x680 [ 34.197635] populate_vma_page_range+0x2db/0x3d0 [ 34.202373] ? get_user_pages_unlocked+0x5d0/0x5d0 [ 34.207286] ? find_vma+0x34/0x190 [ 34.210819] __mm_populate+0x286/0x4d0 [ 34.214697] ? populate_vma_page_range+0x3d0/0x3d0 [ 34.219639] ? down_read_killable+0x200/0x200 [ 34.224119] ? security_mmap_file+0x176/0x1c0 [ 34.228597] vm_mmap_pgoff+0x27f/0x2c0 [ 34.232500] ? vma_is_stack_for_current+0xd0/0xd0 [ 34.237364] ? putname+0xf2/0x130 [ 34.240821] ? rcu_read_lock_sched_held+0x108/0x120 [ 34.245827] ksys_mmap_pgoff+0x4da/0x660 [ 34.249871] ? do_syscall_64+0x9a/0x820 [ 34.253834] ? find_mergeable_anon_vma+0xd0/0xd0 [ 34.258570] ? trace_hardirqs_on+0xbd/0x2c0 [ 34.262874] ? filp_open+0x80/0x80 [ 34.266394] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.271755] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 34.276843] __x64_sys_mmap+0xe9/0x1b0 [ 34.280713] do_syscall_64+0x1b9/0x820 [ 34.284581] ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe [ 34.289948] ? syscall_return_slowpath+0x5e0/0x5e0 [ 34.294858] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 34.299678] ? trace_hardirqs_on_caller+0x2b0/0x2b0 [ 34.304692] ? prepare_exit_to_usermode+0x291/0x3b0 [ 34.309689] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 34.314525] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.319709] RIP: 0033:0x443df9 [ 34.322914] 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 [ 34.341818] RSP: 002b:00007ffc82a082e8 EFLAGS: 00000212 ORIG_RAX: 0000000000000009 [ 34.349506] RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443df9 [ 34.356795] RDX: 00000000000000ff RSI: 0000000000200000 RDI: 0000000020e00000