[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 11.862522] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.573677] random: sshd: uninitialized urandom read (32 bytes read) [ 20.891974] random: sshd: uninitialized urandom read (32 bytes read) [ 21.367247] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.195' (ECDSA) to the list of known hosts. [ 27.012773] urandom_read: 1 callbacks suppressed [ 27.012776] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.222256] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.230739] IP: [] l2tp_session_free+0x11c/0x200 [ 27.237428] PGD 1c2fe4067 [ 27.240158] PUD 1c7c2d067 PMD 0 [ 27.243672] [ 27.245337] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.249820] Dumping ftrace buffer: [ 27.253504] (ftrace buffer empty) [ 27.257384] Modules linked in: [ 27.260730] CPU: 1 PID: 3696 Comm: syz-executor634 Not tainted 4.9.124-g09eb2ba #83 [ 27.268875] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.278219] task: ffff8801c275c800 task.stack: ffff8801c17e8000 [ 27.284515] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.293749] RSP: 0018:ffff8801c17efc98 EFLAGS: 00010246 [ 27.299207] RAX: dffffc0000000000 RBX: ffff8801c1ed2a00 RCX: 0000000000000000 [ 27.306483] RDX: 1ffff100383d6830 RSI: ffffffff836c4711 RDI: ffff8801c1eb4180 [ 27.313864] RBP: ffff8801c17efcb8 R08: ffff8801c275d0e8 R09: 0000000000000000 [ 27.321125] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c1eb4000 [ 27.328512] R13: ffff8801c1ed2a08 R14: 0000000000000000 R15: 0000000000000000 [ 27.335891] FS: 0000000001278880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.344111] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.349991] CR2: 0000000000000080 CR3: 00000001c51f0000 CR4: 00000000001606f0 [ 27.357396] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.364655] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.372190] Stack: [ 27.374338] ffff8801c2b03300 ffff8801c1ed2a00 ffff8801c2b036d0 ffff8801c2b035d8 [ 27.382679] ffff8801c17efce0 ffffffff836cc022 ffff8801c2b03740 ffff8801c2b03300 [ 27.391164] ffffffff836cbf50 ffff8801c17efd18 ffffffff830281f5 ffff8801c2b03740 [ 27.399367] Call Trace: [ 27.401961] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.408616] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.415028] [] __sk_destruct+0x55/0x590 [ 27.420913] [] sk_destruct+0x63/0x80 [ 27.426269] [] __sk_free+0x4f/0x220 [ 27.431542] [] sk_free+0x2b/0x40 [ 27.436684] [] pppol2tp_release+0x239/0x2e0 [ 27.442946] [] __sock_release+0xd7/0x260 [ 27.448793] [] ? __sock_release+0x260/0x260 [ 27.454886] [] sock_close+0x19/0x20 [ 27.461035] [] __fput+0x263/0x700 [ 27.466380] [] ____fput+0x15/0x20 [ 27.471572] [] task_work_run+0x10c/0x180 [ 27.477650] [] exit_to_usermode_loop+0xfc/0x120 [ 27.483964] [] do_syscall_64+0x364/0x490 [ 27.489678] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.497227] Code: 49 8d bc 24 80 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c6 00 00 00 4d 8b b4 24 80 01 00 00 41 ff 8e 80 00 00 00 74 69 e8 a5 c5 c9 fd 4c 89 ea 48 b8 00 [ 27.526028] RIP [] l2tp_session_free+0x11c/0x200 [ 27.532562] RSP [ 27.536177] CR2: 0000000000000080 [ 27.540413] ---[ end trace a640fc8cfcba0e39 ]--- [ 27.545207] Kernel panic - not syncing: Fatal exception [ 27.551291] Dumping ftrace buffer: [ 27.554974] (ftrace buffer empty) [ 27.559151] Kernel Offset: disabled [ 27.562771] Rebooting in 86400 seconds..