[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.929964] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 16.838913] random: sshd: uninitialized urandom read (32 bytes read) [ 16.993334] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.498203] random: sshd: uninitialized urandom read (32 bytes read) [ 17.631926] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.34' (ECDSA) to the list of known hosts. [ 23.297302] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.485834] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.494276] IP: [] l2tp_session_free+0x11c/0x200 [ 23.500916] PGD 1c30fb067 [ 23.503751] PUD 1bec5f067 PMD 0 [ 23.507277] [ 23.508981] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.513501] Dumping ftrace buffer: [ 23.517233] (ftrace buffer empty) [ 23.521079] Modules linked in: [ 23.524693] CPU: 0 PID: 3795 Comm: syz-executor867 Not tainted 4.9.119-g9dc978d #75 [ 23.532509] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.542104] task: ffff8801b7fb6000 task.stack: ffff8801b64f0000 [ 23.548419] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.557501] RSP: 0018:ffff8801b64f7ca0 EFLAGS: 00010246 [ 23.562950] RAX: dffffc0000000000 RBX: ffff8801b7505180 RCX: 0000000000000000 [ 23.570234] RDX: 1ffff10036ead120 RSI: ffffffff836bf9a1 RDI: ffff8801b7568900 [ 23.577656] RBP: ffff8801b64f7cc0 R08: ffff8801b7fb68e8 R09: 0000000000000000 [ 23.584976] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7568780 [ 23.592245] R13: ffff8801b7505188 R14: 0000000000000000 R15: ffffffff83015be0 [ 23.599773] FS: 0000000002522880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 23.608014] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.613886] CR2: 0000000000000080 CR3: 00000001d0205000 CR4: 00000000001606f0 [ 23.621332] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.629012] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.636290] Stack: [ 23.638462] ffff8801b69e6e80 ffff8801b7505180 ffff8801b69e7250 ffff8801b69e7158 [ 23.646541] ffff8801b64f7ce8 ffffffff836c72b2 ffff8801b69e72c0 ffff8801b69e6e80 [ 23.654926] ffffffff836c71e0 ffff8801b64f7d20 ffffffff830230f5 ffff8801b69e72c0 [ 23.663156] Call Trace: [ 23.665768] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.672535] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.679199] [] __sk_destruct+0x55/0x590 [ 23.684972] [] ? sock_release+0x1c0/0x1c0 [ 23.690768] [] sk_destruct+0x63/0x80 [ 23.696272] [] __sk_free+0x4f/0x220 [ 23.701671] [] sk_free+0x2b/0x40 [ 23.706765] [] pppol2tp_release+0x239/0x2e0 [ 23.712882] [] sock_release+0x96/0x1c0 [ 23.718507] [] sock_close+0x16/0x20 [ 23.723912] [] __fput+0x263/0x700 [ 23.729018] [] ____fput+0x15/0x20 [ 23.734128] [] task_work_run+0x10c/0x180 [ 23.739831] [] exit_to_usermode_loop+0xfc/0x120 [ 23.746285] [] do_syscall_64+0x364/0x490 [ 23.751990] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.758908] 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 f5 f0 c9 fd 4c 89 ea 48 b8 00 [ 23.787672] RIP [] l2tp_session_free+0x11c/0x200 [ 23.794465] RSP [ 23.798090] CR2: 0000000000000080 [ 23.801842] ---[ end trace e87a4dc65886761c ]--- [ 23.806621] Kernel panic - not syncing: Fatal exception [ 23.812555] Dumping ftrace buffer: [ 23.816095] (ftrace buffer empty) [ 23.819848] Kernel Offset: disabled [ 23.823505] Rebooting in 86400 seconds..