[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.832327] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 15.007748] random: sshd: uninitialized urandom read (32 bytes read) [ 15.190681] random: sshd: uninitialized urandom read (32 bytes read) [ 15.893257] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 33.449788] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.25' (ECDSA) to the list of known hosts. [ 38.922343] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 39.191256] ------------[ cut here ]------------ [ 39.196066] refcount_t: underflow; use-after-free. [ 39.201207] WARNING: CPU: 1 PID: 4414 at lib/refcount.c:189 refcount_sub_and_test+0x2e7/0x350 [ 39.209850] Kernel panic - not syncing: panic_on_warn set ... [ 39.209850] [ 39.217202] CPU: 1 PID: 4414 Comm: syz-executor254 Not tainted 4.18.0-rc3-next-20180706+ #1 [ 39.225670] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 39.235003] Call Trace: [ 39.237578] dump_stack+0x1c9/0x2b4 [ 39.241186] ? dump_stack_print_info.cold.2+0x52/0x52 [ 39.246359] panic+0x238/0x4e7 [ 39.249529] ? add_taint.cold.5+0x16/0x16 [ 39.253657] ? __warn.cold.8+0x148/0x1ba [ 39.257704] ? __warn.cold.8+0x117/0x1ba [ 39.261749] ? refcount_sub_and_test+0x2e7/0x350 [ 39.266481] __warn.cold.8+0x163/0x1ba [ 39.270347] ? refcount_sub_and_test+0x2e7/0x350 [ 39.275081] report_bug+0x252/0x2d0 [ 39.278696] do_error_trap+0x1fc/0x4d0 [ 39.282562] ? math_error+0x3e0/0x3e0 [ 39.286342] ? vprintk_default+0x28/0x30 [ 39.290408] ? vprintk_func+0x81/0xe7 [ 39.294187] ? printk+0xa7/0xcf [ 39.297444] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 39.302276] do_invalid_op+0x1b/0x20 [ 39.305977] invalid_op+0x14/0x20 [ 39.309413] RIP: 0010:refcount_sub_and_test+0x2e7/0x350 [ 39.314746] Code: 89 de e8 9c 3e 1a fe 84 db 74 07 31 db e9 46 ff ff ff e8 bc 3d 1a fe 48 c7 c7 c0 61 1a 88 c6 05 1d e7 37 06 01 e8 e9 07 e5 fd <0f> 0b 31 db e9 25 ff ff ff 48 8b bd 28 ff ff ff 89 85 34 ff ff ff [ 39.333897] RSP: 0018:ffff8801ad3a7780 EFLAGS: 00010286 [ 39.339242] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 39.346490] RDX: 0000000000000000 RSI: ffffffff81634381 RDI: ffff8801ad3a7458 [ 39.353738] RBP: ffff8801ad3a7868 R08: ffff8801acdea500 R09: fffffbfff11f1260 [ 39.360988] R10: fffffbfff11f1260 R11: ffffffff88f89303 R12: 00000000ffffffff [ 39.368253] R13: ffff8801ad3a7840 R14: 0000000000000001 R15: ffff8801ccfff480 [ 39.375515] ? vprintk_func+0x81/0xe7 [ 39.379307] ? refcount_inc_not_zero+0x2f0/0x2f0 [ 39.384044] ? trace_hardirqs_off+0xd/0x10 [ 39.388259] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 39.393345] refcount_dec_and_test+0x1a/0x20 [ 39.397732] smap_release_sock+0x76/0x320 [ 39.401856] ? sock_map_alloc+0x410/0x410 [ 39.405984] ? __kasan_slab_free+0x131/0x170 [ 39.410393] ? trace_hardirqs_on+0xd/0x10 [ 39.414520] sock_hash_ctx_update_elem.isra.27+0x8cb/0x1690 [ 39.420209] ? sock_map_free+0x530/0x530 [ 39.424247] ? __fget+0x4d5/0x740 [ 39.427677] ? ksys_dup3+0x690/0x690 [ 39.431367] ? trace_hardirqs_off+0xd/0x10 [ 39.435589] ? lock_acquire+0x1e4/0x540 [ 39.439540] ? fs_reclaim_acquire+0x20/0x20 [ 39.443839] ? lock_acquire+0x1e4/0x540 [ 39.447804] sock_hash_update_elem+0x157/0x2f0 [ 39.452377] ? bpf_sock_hash_update+0x90/0x90 [ 39.456853] ? lock_release+0xa30/0xa30 [ 39.460823] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 39.466337] ? bpf_sock_hash_update+0x90/0x90 [ 39.470818] map_update_elem+0x5c4/0xc90 [ 39.474858] __x64_sys_bpf+0x32d/0x510 [ 39.478722] ? bpf_prog_get+0x20/0x20 [ 39.482503] ? ksys_ioctl+0x81/0xd0 [ 39.486112] do_syscall_64+0x1b9/0x820 [ 39.489977] ? syscall_return_slowpath+0x5e0/0x5e0 [ 39.494896] ? syscall_return_slowpath+0x31d/0x5e0 [ 39.499806] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 39.504819] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 39.509658] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 39.514826] RIP: 0033:0x4457c9 [ 39.517990] Code: e8 3c b6 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 2b 12 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 39.537111] RSP: 002b:00007fb5af7fcdb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 [ 39.544801] RAX: ffffffffffffffda RBX: 00000000006dac5c RCX: 00000000004457c9 [ 39.552049] RDX: 0000000000000020 RSI: 0000000020000000 RDI: 0000000000000002 [ 39.559312] RBP: 00000000006dac58 R08: 0000000000000000 R09: 0000000000000000 [ 39.566558] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [ 39.573809] R13: 00007ffcf3b37fef R14: 00007fb5af7fd9c0 R15: 0000000000000007 [ 39.581414] Dumping ftrace buffer: [ 39.584938] (ftrace buffer empty) [ 39.588625] Kernel Offset: disabled [ 39.592230] Rebooting in 86400 seconds..