[....] 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[ 15.304810] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.029196] random: sshd: uninitialized urandom read (32 bytes read) [ 20.227067] random: sshd: uninitialized urandom read (32 bytes read) [ 20.727591] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.34' (ECDSA) to the list of known hosts. [ 26.357291] urandom_read: 1 callbacks suppressed [ 26.357294] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.580982] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.589475] IP: [] l2tp_session_free+0x11c/0x200 [ 26.595921] PGD 1c6968067 [ 26.598573] PUD 1c6969067 PMD 0 [ 26.602225] [ 26.603861] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.608344] Dumping ftrace buffer: [ 26.611870] (ftrace buffer empty) [ 26.615573] Modules linked in: [ 26.618878] CPU: 1 PID: 3684 Comm: syz-executor921 Not tainted 4.9.119-g9dc978d #23 [ 26.627005] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.636528] task: ffff8801c201c800 task.stack: ffff8801c22d0000 [ 26.642568] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 26.651439] RSP: 0018:ffff8801c22d7ca0 EFLAGS: 00010246 [ 26.656881] RAX: dffffc0000000000 RBX: ffff8801c21cd680 RCX: 0000000000000000 [ 26.664275] RDX: 1ffff100384263a0 RSI: ffffffff836bf9a1 RDI: ffff8801c2131d00 [ 26.671533] RBP: ffff8801c22d7cc0 R08: ffff8801c201d0e8 R09: 0000000000000000 [ 26.678787] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c2131b80 [ 26.686042] R13: ffff8801c21cd688 R14: 0000000000000000 R15: ffffffff83015be0 [ 26.693301] FS: 000000000111f880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 26.701515] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.707378] CR2: 0000000000000080 CR3: 00000001c89a1000 CR4: 00000000001606f0 [ 26.714636] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 26.722158] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 26.729417] Stack: [ 26.731550] ffff8801c2318880 ffff8801c21cd680 ffff8801c2318c50 ffff8801c2318b58 [ 26.739694] ffff8801c22d7ce8 ffffffff836c72b2 ffff8801c2318cc0 ffff8801c2318880 [ 26.747736] ffffffff836c71e0 ffff8801c22d7d20 ffffffff830230f5 ffff8801c2318cc0 [ 26.755780] Call Trace: [ 26.758354] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.765191] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.771624] [] __sk_destruct+0x55/0x590 [ 26.777247] [] ? sock_release+0x1c0/0x1c0 [ 26.783029] [] sk_destruct+0x63/0x80 [ 26.788378] [] __sk_free+0x4f/0x220 [ 26.793767] [] sk_free+0x2b/0x40 [ 26.798775] [] pppol2tp_release+0x239/0x2e0 [ 26.804888] [] sock_release+0x96/0x1c0 [ 26.810418] [] sock_close+0x16/0x20 [ 26.816115] [] __fput+0x263/0x700 [ 26.821206] [] ____fput+0x15/0x20 [ 26.826298] [] task_work_run+0x10c/0x180 [ 26.832004] [] exit_to_usermode_loop+0xfc/0x120 [ 26.838304] [] do_syscall_64+0x364/0x490 [ 26.844002] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.851081] 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 [ 26.879149] RIP [] l2tp_session_free+0x11c/0x200 [ 26.885876] RSP [ 26.889487] CR2: 0000000000000080 [ 26.893491] ---[ end trace b2dbdf5c7ad40c85 ]--- [ 26.898251] Kernel panic - not syncing: Fatal exception [ 26.904201] Dumping ftrace buffer: [ 26.907727] (ftrace buffer empty) [ 26.911425] Kernel Offset: disabled [ 26.915037] Rebooting in 86400 seconds..