[....] 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[ 12.631881] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.828954] random: sshd: uninitialized urandom read (32 bytes read) [ 21.135152] random: sshd: uninitialized urandom read (32 bytes read) [ 21.657166] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.41' (ECDSA) to the list of known hosts. [ 27.285263] urandom_read: 1 callbacks suppressed [ 27.285267] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.522484] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.530821] IP: [] l2tp_session_free+0x11c/0x200 [ 27.537239] PGD 1b9390067 [ 27.539878] PUD 1b9c14067 PMD 0 [ 27.543356] [ 27.544978] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.549447] Dumping ftrace buffer: [ 27.552964] (ftrace buffer empty) [ 27.556646] Modules linked in: [ 27.559934] CPU: 1 PID: 3800 Comm: syz-executor310 Not tainted 4.9.122-g54068d6 #78 [ 27.567696] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.577024] task: ffff8801b91d0000 task.stack: ffff8801d9520000 [ 27.583052] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.591894] RSP: 0018:ffff8801d9527ca0 EFLAGS: 00010246 [ 27.597313] RAX: dffffc0000000000 RBX: ffff8801c9c4b180 RCX: 0000000000000000 [ 27.604556] RDX: 1ffff10036d0fa10 RSI: ffffffff836c39a1 RDI: ffff8801b687d080 [ 27.611800] RBP: ffff8801d9527cc0 R08: ffff8801b91d08e8 R09: 0000000000000000 [ 27.619041] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b687cf00 [ 27.626285] R13: ffff8801c9c4b188 R14: 0000000000000000 R15: ffffffff83019be0 [ 27.633531] FS: 0000000000a72880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.641731] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.647587] CR2: 0000000000000080 CR3: 00000001cb3ef000 CR4: 00000000001606f0 [ 27.654830] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.662073] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.669316] Stack: [ 27.671437] ffff8801d95a1100 ffff8801c9c4b180 ffff8801d95a14d0 ffff8801d95a13d8 [ 27.679418] ffff8801d9527ce8 ffffffff836cb2b2 ffff8801d95a1540 ffff8801d95a1100 [ 27.687405] ffffffff836cb1e0 ffff8801d9527d20 ffffffff830270f5 ffff8801d95a1540 [ 27.695393] Call Trace: [ 27.697959] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.704597] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.710892] [] __sk_destruct+0x55/0x590 [ 27.716671] [] ? sock_release+0x1c0/0x1c0 [ 27.722459] [] sk_destruct+0x63/0x80 [ 27.727814] [] __sk_free+0x4f/0x220 [ 27.733072] [] sk_free+0x2b/0x40 [ 27.738069] [] pppol2tp_release+0x239/0x2e0 [ 27.744018] [] sock_release+0x96/0x1c0 [ 27.749547] [] sock_close+0x16/0x20 [ 27.754804] [] __fput+0x263/0x700 [ 27.759890] [] ____fput+0x15/0x20 [ 27.764974] [] task_work_run+0x10c/0x180 [ 27.770671] [] exit_to_usermode_loop+0xfc/0x120 [ 27.776967] [] do_syscall_64+0x364/0x490 [ 27.782660] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.789561] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 27.816752] RIP [] l2tp_session_free+0x11c/0x200 [ 27.823259] RSP [ 27.826860] CR2: 0000000000000080 [ 27.830729] ---[ end trace c92f35c9b86408f7 ]--- [ 27.835489] Kernel panic - not syncing: Fatal exception [ 27.841181] Dumping ftrace buffer: [ 27.844700] (ftrace buffer empty) [ 27.848386] Kernel Offset: disabled [ 27.851985] Rebooting in 86400 seconds..