[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.618832] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.678061] random: sshd: uninitialized urandom read (32 bytes read) [ 16.009102] random: sshd: uninitialized urandom read (32 bytes read) [ 16.922725] random: sshd: uninitialized urandom read (32 bytes read) [ 17.052908] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.12' (ECDSA) to the list of known hosts. [ 22.452032] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 22.655904] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 22.664120] IP: [] l2tp_session_free+0x11c/0x200 [ 22.670542] PGD 1c529d067 [ 22.673181] PUD 1c519f067 PMD 0 [ 22.676666] [ 22.678284] Oops: 0002 [#1] PREEMPT SMP KASAN [ 22.682749] Dumping ftrace buffer: [ 22.686258] (ftrace buffer empty) [ 22.689940] Modules linked in: [ 22.693234] CPU: 0 PID: 3804 Comm: syz-executor370 Not tainted 4.9.113-g47bbcd6 #10 [ 22.701002] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 22.710325] task: ffff8801b8831800 task.stack: ffff8801b57d8000 [ 22.716351] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 22.725196] RSP: 0018:ffff8801b57dfca0 EFLAGS: 00010246 [ 22.730612] RAX: dffffc0000000000 RBX: ffff8801b55ae500 RCX: 0000000000000000 [ 22.737852] RDX: 1ffff10039765080 RSI: ffffffff836bcce1 RDI: ffff8801cbb28400 [ 22.745092] RBP: ffff8801b57dfcc0 R08: ffff8801b88320e8 R09: 0000000000000000 [ 22.752335] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cbb28280 [ 22.759576] R13: ffff8801b55ae508 R14: 0000000000000000 R15: ffffffff83013be0 [ 22.766819] FS: 00000000018e1880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 22.775025] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.775030] CR2: 0000000000000080 CR3: 00000001c52f4000 CR4: 00000000001606f0 [ 22.775039] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 22.775043] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 22.775044] Stack: [ 22.775054] ffff8801b547d500 ffff8801b55ae500 ffff8801b547d8d0 ffff8801b547d7d8 [ 22.775062] ffff8801b57dfce8 ffffffff836c45f2 ffff8801b547d940 ffff8801b547d500 [ 22.775071] ffffffff836c4520 ffff8801b57dfd20 ffffffff83021095 ffff8801b547d940 [ 22.775073] Call Trace: [ 22.775087] [] pppol2tp_session_destruct+0xd2/0x110 [ 22.775094] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 22.775102] [] __sk_destruct+0x55/0x590 [ 22.775109] [] ? sock_release+0x1c0/0x1c0 [ 22.775115] [] sk_destruct+0x63/0x80 [ 22.775122] [] __sk_free+0x4f/0x220 [ 22.775128] [] sk_free+0x2b/0x40 [ 22.775134] [] pppol2tp_release+0x239/0x2e0 [ 22.775141] [] sock_release+0x96/0x1c0 [ 22.775147] [] sock_close+0x16/0x20 [ 22.775156] [] __fput+0x263/0x700 [ 22.775163] [] ____fput+0x15/0x20 [ 22.775171] [] task_work_run+0x10c/0x180 [ 22.775179] [] exit_to_usermode_loop+0xfc/0x120 [ 22.775185] [] do_syscall_64+0x364/0x490 [ 22.775193] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.775298] 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 [ 22.775305] RIP [] l2tp_session_free+0x11c/0x200 [ 22.775307] RSP [ 22.775310] CR2: 0000000000000080 [ 22.777119] ---[ end trace e83cd681dfacd2a1 ]--- [ 22.777123] Kernel panic - not syncing: Fatal exception [ 22.781326] Dumping ftrace buffer: [ 22.781329] (ftrace buffer empty) [ 22.781332] Kernel Offset: disabled [ 22.974536] Rebooting in 86400 seconds..