[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 23.980386] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 29.936133] random: sshd: uninitialized urandom read (32 bytes read) [ 30.212218] random: sshd: uninitialized urandom read (32 bytes read) [ 30.780243] random: sshd: uninitialized urandom read (32 bytes read) [ 30.950352] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.195' (ECDSA) to the list of known hosts. [ 36.541854] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 36.642360] [ 36.644027] ====================================================== [ 36.650335] WARNING: possible circular locking dependency detected [ 36.656632] 4.19.0-rc1+ #120 Not tainted [ 36.660676] ------------------------------------------------------ [ 36.666980] syz-executor964/4654 is trying to acquire lock: [ 36.672690] 00000000f13df4c6 (&rp->fetch_lock){+.+.}, at: mon_bin_vma_fault+0xdc/0x4a0 [ 36.680746] [ 36.680746] but task is already holding lock: [ 36.686711] 000000003b4b7c07 (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 36.694353] [ 36.694353] which lock already depends on the new lock. [ 36.694353] [ 36.702653] [ 36.702653] the existing dependency chain (in reverse order) is: [ 36.710259] [ 36.710259] -> #1 (&mm->mmap_sem){++++}: [ 36.715859] __might_fault+0x155/0x1e0 [ 36.720256] _copy_to_user+0x30/0x110 [ 36.724559] mon_bin_read+0x334/0x650 [ 36.728896] __vfs_read+0x117/0x9b0 [ 36.733052] vfs_read+0x17f/0x3c0 [ 36.737020] ksys_pread64+0x181/0x1b0 [ 36.741339] __ia32_compat_sys_x86_pread+0xc4/0x130 [ 36.746861] do_fast_syscall_32+0x34d/0xfb2 [ 36.751713] entry_SYSENTER_compat+0x70/0x7f [ 36.756628] [ 36.756628] -> #0 (&rp->fetch_lock){+.+.}: [ 36.762334] lock_acquire+0x1e4/0x4f0 [ 36.766639] __mutex_lock+0x171/0x1700 [ 36.771028] mutex_lock_nested+0x16/0x20 [ 36.775594] mon_bin_vma_fault+0xdc/0x4a0 [ 36.780269] __do_fault+0xee/0x450 [ 36.784311] __handle_mm_fault+0x2b4a/0x4350 [ 36.789220] handle_mm_fault+0x53e/0xc80 [ 36.793784] __get_user_pages+0x823/0x1b50 [ 36.798521] populate_vma_page_range+0x2db/0x3d0 [ 36.803802] __mm_populate+0x286/0x4d0 [ 36.808240] vm_mmap_pgoff+0x27f/0x2c0 [ 36.812631] ksys_mmap_pgoff+0x4da/0x660 [ 36.817197] __ia32_sys_mmap_pgoff+0xdd/0x1a0 [ 36.822204] do_fast_syscall_32+0x34d/0xfb2 [ 36.827044] entry_SYSENTER_compat+0x70/0x7f [ 36.831949] [ 36.831949] other info that might help us debug this: [ 36.831949] [ 36.840069] Possible unsafe locking scenario: [ 36.840069] [ 36.846101] CPU0 CPU1 [ 36.850746] ---- ---- [ 36.855387] lock(&mm->mmap_sem); [ 36.858921] lock(&rp->fetch_lock); [ 36.865130] lock(&mm->mmap_sem); [ 36.871181] lock(&rp->fetch_lock); [ 36.874889] [ 36.874889] *** DEADLOCK *** [ 36.874889] [ 36.880933] 1 lock held by syz-executor964/4654: [ 36.885665] #0: 000000003b4b7c07 (&mm->mmap_sem){++++}, at: __mm_populate+0x31a/0x4d0 [ 36.893740] [ 36.893740] stack backtrace: [ 36.898219] CPU: 0 PID: 4654 Comm: syz-executor964 Not tainted 4.19.0-rc1+ #120 [ 36.905641] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 36.914975] Call Trace: [ 36.917565] dump_stack+0x1c9/0x2b4 [ 36.921192] ? dump_stack_print_info.cold.2+0x52/0x52 [ 36.926396] ? vprintk_func+0x81/0x117 [ 36.930268] print_circular_bug.isra.34.cold.55+0x1bd/0x27d [ 36.935978] ? save_trace+0xe0/0x290 [ 36.939680] __lock_acquire+0x3449/0x5020 [ 36.943854] ? __isolate_free_page+0x690/0x690 [ 36.948424] ? mark_held_locks+0x160/0x160 [ 36.952641] ? print_usage_bug+0xc0/0xc0 [ 36.956700] ? __lock_acquire+0x7fc/0x5020 [ 36.960918] ? print_usage_bug+0xc0/0xc0 [ 36.964961] ? mark_held_locks+0x160/0x160 [ 36.969200] ? __lock_acquire+0x7fc/0x5020 [ 36.973421] ? mark_held_locks+0x160/0x160 [ 36.977640] ? mark_held_locks+0x160/0x160 [ 36.981856] ? graph_lock+0x170/0x170 [ 36.985638] ? mark_held_locks+0x160/0x160 [ 36.989874] ? print_usage_bug+0xc0/0xc0 [ 36.993921] lock_acquire+0x1e4/0x4f0 [ 36.997715] ? mon_bin_vma_fault+0xdc/0x4a0 [ 37.002021] ? lock_release+0x9f0/0x9f0 [ 37.005980] ? check_same_owner+0x340/0x340 [ 37.010304] ? rcu_note_context_switch+0x680/0x680 [ 37.015244] __mutex_lock+0x171/0x1700 [ 37.019156] ? mon_bin_vma_fault+0xdc/0x4a0 [ 37.023464] ? mon_bin_vma_fault+0xdc/0x4a0 [ 37.027780] ? mutex_trylock+0x2b0/0x2b0 [ 37.031851] ? __lock_acquire+0x7fc/0x5020 [ 37.036076] ? mark_held_locks+0x160/0x160 [ 37.040294] ? mark_held_locks+0x160/0x160 [ 37.044511] ? mark_held_locks+0x160/0x160 [ 37.048756] ? kasan_check_write+0x14/0x20 [ 37.052986] ? do_raw_spin_lock+0xc1/0x200 [ 37.057209] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 37.062296] ? print_usage_bug+0xc0/0xc0 [ 37.066339] ? graph_lock+0x170/0x170 [ 37.070139] ? print_usage_bug+0xc0/0xc0 [ 37.074183] ? __lock_acquire+0x7fc/0x5020 [ 37.078401] ? graph_lock+0x170/0x170 [ 37.082184] ? kasan_slab_free+0xe/0x10 [ 37.086143] ? print_usage_bug+0xc0/0xc0 [ 37.090189] ? __lock_acquire+0x7fc/0x5020 [ 37.094411] mutex_lock_nested+0x16/0x20 [ 37.098455] ? mutex_lock_nested+0x16/0x20 [ 37.102678] mon_bin_vma_fault+0xdc/0x4a0 [ 37.106816] ? mon_alloc_buff+0x200/0x200 [ 37.110955] ? mark_held_locks+0x160/0x160 [ 37.115171] ? lockdep_hardirqs_on+0x421/0x5c0 [ 37.119748] __do_fault+0xee/0x450 [ 37.123288] ? pmd_devmap_trans_unstable+0x1d0/0x1d0 [ 37.128380] ? do_raw_spin_lock+0xc1/0x200 [ 37.132598] ? pud_val+0x88/0x100 [ 37.136033] ? pmd_val+0x100/0x100 [ 37.139559] ? depot_save_stack+0x291/0x470 [ 37.143867] __handle_mm_fault+0x2b4a/0x4350 [ 37.148260] ? vmf_insert_mixed_mkwrite+0xa0/0xa0 [ 37.153086] ? graph_lock+0x170/0x170 [ 37.156982] ? lock_downgrade+0x8f0/0x8f0 [ 37.161124] ? handle_mm_fault+0x8c4/0xc80 [ 37.165340] ? handle_mm_fault+0x8c4/0xc80 [ 37.169558] ? kasan_check_read+0x11/0x20 [ 37.173711] ? rcu_is_watching+0x8c/0x150 [ 37.177846] ? __get_user_pages+0x823/0x1b50 [ 37.182240] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 37.186895] handle_mm_fault+0x53e/0xc80 [ 37.190937] ? __handle_mm_fault+0x4350/0x4350 [ 37.195502] ? check_same_owner+0x340/0x340 [ 37.199815] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 37.204834] __get_user_pages+0x823/0x1b50 [ 37.209056] ? follow_page_mask+0x1e30/0x1e30 [ 37.216234] ? lock_acquire+0x1e4/0x4f0 [ 37.220212] ? __mm_populate+0x31a/0x4d0 [ 37.224258] ? lock_release+0x9f0/0x9f0 [ 37.228215] ? check_same_owner+0x340/0x340 [ 37.232520] ? rcu_note_context_switch+0x680/0x680 [ 37.237435] populate_vma_page_range+0x2db/0x3d0 [ 37.242175] ? get_user_pages_unlocked+0x5d0/0x5d0 [ 37.247091] ? find_vma+0x34/0x190 [ 37.250616] __mm_populate+0x286/0x4d0 [ 37.254490] ? populate_vma_page_range+0x3d0/0x3d0 [ 37.259407] ? down_read_killable+0x200/0x200 [ 37.263890] ? security_mmap_file+0x176/0x1c0 [ 37.268370] vm_mmap_pgoff+0x27f/0x2c0 [ 37.272243] ? vma_is_stack_for_current+0xd0/0xd0 [ 37.277085] ? putname+0xf2/0x130 [ 37.280525] ? rcu_read_lock_sched_held+0x108/0x120 [ 37.285524] ksys_mmap_pgoff+0x4da/0x660 [ 37.289570] ? do_fast_syscall_32+0x150/0xfb2 [ 37.294053] ? find_mergeable_anon_vma+0xd0/0xd0 [ 37.298810] ? trace_hardirqs_on+0xbd/0x2c0 [ 37.303137] ? filp_open+0x80/0x80 [ 37.306664] ? entry_SYSENTER_compat+0x70/0x7f [ 37.311249] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 37.316574] __ia32_sys_mmap_pgoff+0xdd/0x1a0 [ 37.321057] do_fast_syscall_32+0x34d/0xfb2 [ 37.325367] ? do_int80_syscall_32+0x890/0x890 [ 37.329952] ? entry_SYSENTER_compat+0x68/0x7f [ 37.334521] ? trace_hardirqs_off_caller+0xbb/0x2b0 [ 37.339525] ? syscall_return_slowpath+0x5e0/0x5e0 [ 37.344438] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 37.349270] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 37.354103] ? trace_hardirqs_on_caller+0x2b0/0x2b0 [ 37.359104] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 37.364104] ? prepare_exit_to_usermode+0x291/0x3b0 [ 37.369105] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 37.373938] entry_SYSENTER_compat+0x70/0x7f [ 37.378348] RIP: 0023:0xf7f14ca9 [ 37.381704] 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 9