[....] 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[ 13.821838] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.949586] random: sshd: uninitialized urandom read (32 bytes read) [ 22.143892] random: sshd: uninitialized urandom read (32 bytes read) [ 22.629488] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.8' (ECDSA) to the list of known hosts. [ 28.287561] urandom_read: 1 callbacks suppressed [ 28.287564] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.514682] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.522960] IP: [] l2tp_session_free+0x11c/0x200 [ 28.529389] PGD 1cb7fa067 [ 28.532031] PUD 1cb7cf067 PMD 0 [ 28.535505] [ 28.537123] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.541588] Dumping ftrace buffer: [ 28.545101] (ftrace buffer empty) [ 28.548794] Modules linked in: [ 28.552193] CPU: 1 PID: 3805 Comm: syz-executor248 Not tainted 4.9.121-g681e57b #77 [ 28.560007] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.569442] task: ffff8801bec06000 task.stack: ffff8801b61d0000 [ 28.575473] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.584320] RSP: 0018:ffff8801b61d7ca0 EFLAGS: 00010246 [ 28.589742] RAX: dffffc0000000000 RBX: ffff8801b63bec80 RCX: 0000000000000000 [ 28.597032] RDX: 1ffff10036c3c350 RSI: ffffffff836c29a1 RDI: ffff8801b61e1a80 [ 28.604284] RBP: ffff8801b61d7cc0 R08: ffff8801bec068e8 R09: 0000000000000000 [ 28.611532] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b61e1900 [ 28.618777] R13: ffff8801b63bec88 R14: 0000000000000000 R15: ffffffff83018be0 [ 28.626075] FS: 0000000001bc4880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 28.634283] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.640140] CR2: 0000000000000080 CR3: 00000001c953b000 CR4: 00000000001606f0 [ 28.647386] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.654630] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.661875] Stack: [ 28.664045] ffff8801b66af700 ffff8801b63bec80 ffff8801b66afad0 ffff8801b66af9d8 [ 28.672034] ffff8801b61d7ce8 ffffffff836ca2b2 ffff8801b66afb40 ffff8801b66af700 [ 28.680036] ffffffff836ca1e0 ffff8801b61d7d20 ffffffff830260f5 ffff8801b66afb40 [ 28.688032] Call Trace: [ 28.690596] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.697244] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.703538] [] __sk_destruct+0x55/0x590 [ 28.709144] [] ? sock_release+0x1c0/0x1c0 [ 28.714918] [] sk_destruct+0x63/0x80 [ 28.720259] [] __sk_free+0x4f/0x220 [ 28.725514] [] sk_free+0x2b/0x40 [ 28.730510] [] pppol2tp_release+0x239/0x2e0 [ 28.736460] [] sock_release+0x96/0x1c0 [ 28.742017] [] sock_close+0x16/0x20 [ 28.747285] [] __fput+0x263/0x700 [ 28.752363] [] ____fput+0x15/0x20 [ 28.757452] [] task_work_run+0x10c/0x180 [ 28.763184] [] exit_to_usermode_loop+0xfc/0x120 [ 28.769533] [] do_syscall_64+0x364/0x490 [ 28.775270] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.782176] 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 65 df c9 fd 4c 89 ea 48 b8 00 [ 28.809181] RIP [] l2tp_session_free+0x11c/0x200 [ 28.815690] RSP [ 28.819289] CR2: 0000000000000080 [ 28.823087] ---[ end trace aac87f131332078b ]--- [ 28.827847] Kernel panic - not syncing: Fatal exception [ 28.833545] Dumping ftrace buffer: [ 28.837062] (ftrace buffer empty) [ 28.840744] Kernel Offset: disabled [ 28.844342] Rebooting in 86400 seconds..