[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.446875] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.443925] random: sshd: uninitialized urandom read (32 bytes read) [ 27.894491] random: sshd: uninitialized urandom read (32 bytes read) [ 28.395352] random: sshd: uninitialized urandom read (32 bytes read) [ 28.528760] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.4' (ECDSA) to the list of known hosts. [ 34.011061] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.214400] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.222616] IP: [] l2tp_session_free+0x11c/0x200 [ 34.229064] PGD 1c44c9067 [ 34.231706] PUD 1c9237067 PMD 0 [ 34.235253] [ 34.236881] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.241390] Dumping ftrace buffer: [ 34.244915] (ftrace buffer empty) [ 34.248601] Modules linked in: [ 34.251889] CPU: 1 PID: 3753 Comm: syz-executor987 Not tainted 4.9.118-g856452b #21 [ 34.259653] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.268986] task: ffff8801be960000 task.stack: ffff8801bd180000 [ 34.275017] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.283870] RSP: 0018:ffff8801bd187ca0 EFLAGS: 00010246 [ 34.289316] RAX: dffffc0000000000 RBX: ffff8801bd1f5180 RCX: 0000000000000000 [ 34.296566] RDX: 1ffff100393e42b0 RSI: ffffffff836bf781 RDI: ffff8801c9f21580 [ 34.303811] RBP: ffff8801bd187cc0 R08: ffff8801be9608e8 R09: 0000000000000000 [ 34.311052] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9f21400 [ 34.318300] R13: ffff8801bd1f5188 R14: 0000000000000000 R15: ffffffff83015be0 [ 34.325553] FS: 0000000001f59880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 34.333756] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.339612] CR2: 0000000000000080 CR3: 00000001c6173000 CR4: 00000000001606f0 [ 34.346903] Stack: [ 34.349037] ffff8801bf6f6e80 ffff8801bd1f5180 ffff8801bf6f7250 ffff8801bf6f7158 [ 34.357098] ffff8801bd187ce8 ffffffff836c7092 ffff8801bf6f72c0 ffff8801bf6f6e80 [ 34.365105] ffffffff836c6fc0 ffff8801bd187d20 ffffffff830230f5 ffff8801bf6f72c0 [ 34.373158] Call Trace: [ 34.375723] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.382375] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.388672] [] __sk_destruct+0x55/0x590 [ 34.394276] [] ? sock_release+0x1c0/0x1c0 [ 34.400058] [] sk_destruct+0x63/0x80 [ 34.405396] [] __sk_free+0x4f/0x220 [ 34.410646] [] sk_free+0x2b/0x40 [ 34.415640] [] pppol2tp_release+0x239/0x2e0 [ 34.421589] [] sock_release+0x96/0x1c0 [ 34.427102] [] sock_close+0x16/0x20 [ 34.432355] [] __fput+0x263/0x700 [ 34.437434] [] ____fput+0x15/0x20 [ 34.442515] [] task_work_run+0x10c/0x180 [ 34.448201] [] exit_to_usermode_loop+0xfc/0x120 [ 34.454495] [] do_syscall_64+0x364/0x490 [ 34.460182] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.467080] 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 f2 c9 fd 4c 89 ea 48 b8 00 [ 34.494394] RIP [] l2tp_session_free+0x11c/0x200 [ 34.500897] RSP [ 34.504558] CR2: 0000000000000080 [ 34.508126] ---[ end trace 03017a6e8359b653 ]--- [ 34.512879] Kernel panic - not syncing: Fatal exception [ 34.518518] Dumping ftrace buffer: [ 34.522040] (ftrace buffer empty) [ 34.525721] Kernel Offset: disabled [ 34.529318] Rebooting in 86400 seconds..