[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.515406] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.437187] random: sshd: uninitialized urandom read (32 bytes read) [ 26.918670] random: sshd: uninitialized urandom read (32 bytes read) [ 27.583601] random: sshd: uninitialized urandom read (32 bytes read) [ 27.716203] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.61' (ECDSA) to the list of known hosts. [ 33.165527] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 33.368525] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 33.376770] IP: [] l2tp_session_free+0x11c/0x200 [ 33.383187] PGD 1c5525067 [ 33.385834] PUD 1ca6dc067 PMD 0 [ 33.389334] [ 33.390966] Oops: 0002 [#1] PREEMPT SMP KASAN [ 33.395439] Dumping ftrace buffer: [ 33.398962] (ftrace buffer empty) [ 33.402650] Modules linked in: [ 33.406034] CPU: 1 PID: 3720 Comm: syz-executor603 Not tainted 4.9.113-g47bbcd6 #62 [ 33.413799] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.423127] task: ffff8801c0d5b000 task.stack: ffff8801bf130000 [ 33.429169] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 33.438037] RSP: 0018:ffff8801bf137ca0 EFLAGS: 00010246 [ 33.443468] RAX: dffffc0000000000 RBX: ffff8801bf168c80 RCX: 0000000000000000 [ 33.450714] RDX: 1ffff10039260350 RSI: ffffffff836bcce1 RDI: ffff8801c9301a80 [ 33.457957] RBP: ffff8801bf137cc0 R08: ffff8801c0d5b8e8 R09: 0000000000000000 [ 33.465212] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9301900 [ 33.472609] R13: ffff8801bf168c88 R14: 0000000000000000 R15: ffffffff83013be0 [ 33.479944] FS: 0000000001282880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 33.488155] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 33.494186] CR2: 0000000000000080 CR3: 00000001c57bd000 CR4: 00000000001606f0 [ 33.501443] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 33.508726] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 33.515992] Stack: [ 33.518133] ffff8801bf943b80 ffff8801bf168c80 ffff8801bf943f50 ffff8801bf943e58 [ 33.526140] ffff8801bf137ce8 ffffffff836c45f2 ffff8801bf943fc0 ffff8801bf943b80 [ 33.534133] ffffffff836c4520 ffff8801bf137d20 ffffffff83021095 ffff8801bf943fc0 [ 33.542134] Call Trace: [ 33.544701] [] pppol2tp_session_destruct+0xd2/0x110 [ 33.551340] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 33.557642] [] __sk_destruct+0x55/0x590 [ 33.563254] [] ? sock_release+0x1c0/0x1c0 [ 33.569026] [] sk_destruct+0x63/0x80 [ 33.574361] [] __sk_free+0x4f/0x220 [ 33.579609] [] sk_free+0x2b/0x40 [ 33.584600] [] pppol2tp_release+0x239/0x2e0 [ 33.590569] [] sock_release+0x96/0x1c0 [ 33.596080] [] sock_close+0x16/0x20 [ 33.601330] [] __fput+0x263/0x700 [ 33.606596] [] ____fput+0x15/0x20 [ 33.611682] [] task_work_run+0x10c/0x180 [ 33.617365] [] exit_to_usermode_loop+0xfc/0x120 [ 33.623657] [] do_syscall_64+0x364/0x490 [ 33.629340] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 33.636231] 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 55 1d ca fd 4c 89 ea 48 b8 00 [ 33.663239] RIP [] l2tp_session_free+0x11c/0x200 [ 33.669736] RSP [ 33.673331] CR2: 0000000000000080 [ 33.678280] ---[ end trace 8f0ba6cde556cec6 ]--- [ 33.683077] Kernel panic - not syncing: Fatal exception [ 33.688912] Dumping ftrace buffer: [ 33.692424] (ftrace buffer empty) [ 33.696121] Kernel Offset: disabled [ 33.699720] Rebooting in 86400 seconds..