[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 20.487918] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 21.724246] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.985763] random: sshd: uninitialized urandom read (32 bytes read) [ 22.855865] random: sshd: uninitialized urandom read (32 bytes read) [ 23.023447] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.20' (ECDSA) to the list of known hosts. [ 28.516497] 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 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 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 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 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 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 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 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 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 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 [ 31.065390] ------------[ cut here ]------------ [ 31.070391] refcount_t: underflow; use-after-free. [ 31.075551] WARNING: CPU: 1 PID: 4551 at lib/refcount.c:187 refcount_sub_and_test+0x2e7/0x350 [ 31.084228] Kernel panic - not syncing: panic_on_warn set ... [ 31.084228] [ 31.091594] CPU: 1 PID: 4551 Comm: syz-executor411 Not tainted 4.18.0-rc4+ #144 [ 31.099033] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.108557] Call Trace: [ 31.111138] dump_stack+0x1c9/0x2b4 executing program executing program [ 31.114767] ? dump_stack_print_info.cold.2+0x52/0x52 [ 31.119963] panic+0x238/0x4e7 [ 31.123165] ? add_taint.cold.5+0x16/0x16 [ 31.127313] ? __warn.cold.8+0x148/0x1ba [ 31.131356] ? __warn.cold.8+0x117/0x1ba [ 31.135410] ? refcount_sub_and_test+0x2e7/0x350 [ 31.140169] __warn.cold.8+0x163/0x1ba [ 31.144064] ? refcount_sub_and_test+0x2e7/0x350 [ 31.148810] report_bug+0x252/0x2d0 [ 31.152422] do_error_trap+0x1fc/0x4d0 [ 31.156311] ? math_error+0x3e0/0x3e0 [ 31.160118] ? vprintk_default+0x28/0x30 executing program [ 31.164176] ? vprintk_func+0x81/0xe7 [ 31.167958] ? printk+0xa7/0xcf [ 31.171240] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 31.176086] do_invalid_op+0x1b/0x20 [ 31.179790] invalid_op+0x14/0x20 [ 31.183230] RIP: 0010:refcount_sub_and_test+0x2e7/0x350 [ 31.188571] Code: 89 de e8 1c ac 1c fe 84 db 74 07 31 db e9 46 ff ff ff e8 3c ab 1c fe 48 c7 c7 80 47 1a 88 c6 05 f6 62 3a 06 01 e8 19 ce e7 fd <0f> 0b 31 db e9 25 ff ff ff 48 8b bd 28 ff ff ff 89 85 34 ff ff ff [ 31.207880] RSP: 0018:ffff8801d918f780 EFLAGS: 00010286 executing program executing program [ 31.213248] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 31.220503] RDX: 0000000000000000 RSI: ffffffff81631821 RDI: ffff8801d918f458 [ 31.227766] RBP: ffff8801d918f868 R08: ffff8801d97a80c0 R09: 0000000000000006 [ 31.235039] R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff [ 31.242300] R13: ffff8801d918f840 R14: 0000000000000001 R15: 0000000000000000 [ 31.249594] ? vprintk_func+0x81/0xe7 [ 31.253388] ? refcount_inc_not_zero+0x2f0/0x2f0 [ 31.258127] ? graph_lock+0x170/0x170 [ 31.261937] refcount_dec_and_test+0x1a/0x20 executing program [ 31.266349] smap_release_sock+0x76/0x320 [ 31.270485] ? sock_map_alloc+0x410/0x410 [ 31.274620] sock_hash_ctx_update_elem.isra.27+0x8cb/0x1690 [ 31.280335] ? sock_map_free+0x530/0x530 [ 31.284404] ? rcu_is_watching+0x8c/0x150 [ 31.288553] ? rcu_report_qs_rnp+0x7a0/0x7a0 [ 31.292955] ? __fget+0x414/0x670 [ 31.296410] ? expand_files.part.8+0x9c0/0x9c0 [ 31.300991] ? find_held_lock+0x36/0x1c0 [ 31.305057] sock_hash_update_elem+0x157/0x2f0 [ 31.309635] ? bpf_sock_hash_update+0x90/0x90 executing program executing program [ 31.314127] ? kasan_check_read+0x11/0x20 [ 31.318268] ? rcu_is_watching+0x8c/0x150 [ 31.322410] ? rcu_report_qs_rnp+0x7a0/0x7a0 [ 31.326831] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 31.332363] ? bpf_sock_hash_update+0x90/0x90 [ 31.336853] map_update_elem+0x5c4/0xc90 [ 31.340901] __x64_sys_bpf+0x32d/0x510 [ 31.344768] ? bpf_prog_get+0x20/0x20 [ 31.348567] ? ksys_ioctl+0x81/0xd0 [ 31.352205] ? do_syscall_64+0x9a/0x820 [ 31.356188] do_syscall_64+0x1b9/0x820 [ 31.360062] ? finish_task_switch+0x1d3/0x870 executing program [ 31.364544] ? syscall_return_slowpath+0x5e0/0x5e0 [ 31.369467] ? syscall_return_slowpath+0x31d/0x5e0 [ 31.374398] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 31.379746] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 31.384589] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 31.389771] RIP: 0033:0x4457a9 [ 31.392939] 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 executing program [ 31.412145] RSP: 002b:00007f47b2c6fdb8 EFLAGS: 00000297 ORIG_RAX: 0000000000000141 [ 31.419848] RAX: ffffffffffffffda RBX: 00000000006dac24 RCX: 00000000004457a9 [ 31.427149] RDX: 0000000000000020 RSI: 0000000020000180 RDI: 0000000000000002 [ 31.434405] RBP: 00000000006dac20 R08: 0000000000000000 R09: 0000000000000000 [ 31.441695] R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000000 [ 31.448981] R13: 00007ffce5a4834f R14: 00007f47b2c709c0 R15: 0000000000000007 [ 31.456937] Dumping ftrace buffer: [ 31.460615] (ftrace buffer empty) [ 31.464307] Kernel Offset: disabled [ 31.467926] Rebooting in 86400 seconds..