[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.513021] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.840053] random: sshd: uninitialized urandom read (32 bytes read) [ 17.198909] random: sshd: uninitialized urandom read (32 bytes read) [ 17.765350] random: sshd: uninitialized urandom read (32 bytes read) [ 25.096471] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.44' (ECDSA) to the list of known hosts. [ 30.722677] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 30.936214] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 30.944514] IP: [] l2tp_session_free+0x11c/0x200 [ 30.950932] PGD 1bf1df067 [ 30.953574] PUD 1c29a7067 PMD 0 [ 30.957046] [ 30.958695] Oops: 0002 [#1] PREEMPT SMP KASAN [ 30.963186] Dumping ftrace buffer: [ 30.966697] (ftrace buffer empty) [ 30.970381] Modules linked in: [ 30.973679] CPU: 1 PID: 3743 Comm: syz-executor852 Not tainted 4.9.122-g54068d6 #78 [ 30.981573] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.990911] task: ffff8801bf644800 task.stack: ffff8801cb7d0000 [ 30.996943] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 31.005798] RSP: 0018:ffff8801cb7d7ca0 EFLAGS: 00010246 [ 31.011279] RAX: dffffc0000000000 RBX: ffff8801be330a00 RCX: 0000000000000000 [ 31.018530] RDX: 1ffff10037c66210 RSI: ffffffff836c39a1 RDI: ffff8801be331080 [ 31.025775] RBP: ffff8801cb7d7cc0 R08: ffff8801bf6450e8 R09: 0000000000000000 [ 31.033016] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801be330f00 [ 31.040271] R13: ffff8801be330a08 R14: 0000000000000000 R15: ffffffff83019be0 [ 31.047525] FS: 00000000024f1880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 31.055727] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 31.061587] CR2: 0000000000000080 CR3: 00000001c2915000 CR4: 00000000001606f0 [ 31.068832] Stack: [ 31.070974] ffff8801cf125500 ffff8801be330a00 ffff8801cf1258d0 ffff8801cf1257d8 [ 31.078978] ffff8801cb7d7ce8 ffffffff836cb2b2 ffff8801cf125940 ffff8801cf125500 [ 31.087082] ffffffff836cb1e0 ffff8801cb7d7d20 ffffffff830270f5 ffff8801cf125940 [ 31.095079] Call Trace: [ 31.097645] [] pppol2tp_session_destruct+0xd2/0x110 [ 31.104583] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 31.110883] [] __sk_destruct+0x55/0x590 [ 31.116483] [] ? sock_release+0x1c0/0x1c0 [ 31.122255] [] sk_destruct+0x63/0x80 [ 31.127592] [] __sk_free+0x4f/0x220 [ 31.132841] [] sk_free+0x2b/0x40 [ 31.137843] [] pppol2tp_release+0x239/0x2e0 [ 31.143786] [] sock_release+0x96/0x1c0 [ 31.149294] [] sock_close+0x16/0x20 [ 31.154547] [] __fput+0x263/0x700 [ 31.159622] [] ____fput+0x15/0x20 [ 31.164706] [] task_work_run+0x10c/0x180 [ 31.170403] [] exit_to_usermode_loop+0xfc/0x120 [ 31.176694] [] do_syscall_64+0x364/0x490 [ 31.182392] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 31.189293] 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 [ 31.216142] RIP [] l2tp_session_free+0x11c/0x200 [ 31.222646] RSP [ 31.226240] CR2: 0000000000000080 [ 31.230044] ---[ end trace 2149c442a2d2c8f8 ]--- [ 31.234831] Kernel panic - not syncing: Fatal exception [ 31.240485] Dumping ftrace buffer: [ 31.244005] (ftrace buffer empty) [ 31.247687] Kernel Offset: disabled [ 31.251297] Rebooting in 86400 seconds..