[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.592700] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.137228] random: sshd: uninitialized urandom read (32 bytes read) [ 27.545276] random: sshd: uninitialized urandom read (32 bytes read) [ 28.063237] random: sshd: uninitialized urandom read (32 bytes read) [ 28.209346] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.20' (ECDSA) to the list of known hosts. [ 33.859169] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.074643] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.082869] IP: [] l2tp_session_free+0x11c/0x200 [ 34.089306] PGD 1bbae4067 [ 34.091954] PUD 1bbb14067 PMD 0 [ 34.095479] [ 34.097115] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.101686] Dumping ftrace buffer: [ 34.105227] (ftrace buffer empty) [ 34.108914] Modules linked in: [ 34.112242] CPU: 0 PID: 3803 Comm: syz-executor011 Not tainted 4.9.122-g54068d6 #78 [ 34.120012] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.129349] task: ffff8801b6693000 task.stack: ffff8801b6338000 [ 34.135463] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.144320] RSP: 0018:ffff8801b633fca0 EFLAGS: 00010246 [ 34.149745] RAX: dffffc0000000000 RBX: ffff8801d97c8000 RCX: 0000000000000000 [ 34.156992] RDX: 1ffff10036cd7c80 RSI: ffffffff836c39a1 RDI: ffff8801b66be400 [ 34.164244] RBP: ffff8801b633fcc0 R08: ffff8801b66938e8 R09: 0000000000000000 [ 34.171492] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b66be280 [ 34.178739] R13: ffff8801d97c8008 R14: 0000000000000000 R15: ffffffff83019be0 [ 34.185988] FS: 000000000087e880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 34.194201] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.200063] CR2: 0000000000000080 CR3: 00000001bb99f000 CR4: 00000000001606f0 [ 34.207315] Stack: [ 34.209450] ffff8801d9788880 ffff8801d97c8000 ffff8801d9788c50 ffff8801d9788b58 [ 34.217497] ffff8801b633fce8 ffffffff836cb2b2 ffff8801d9788cc0 ffff8801d9788880 [ 34.225510] ffffffff836cb1e0 ffff8801b633fd20 ffffffff830270f5 ffff8801d9788cc0 [ 34.233512] Call Trace: [ 34.236085] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.242743] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.249040] [] __sk_destruct+0x55/0x590 [ 34.254762] [] ? sock_release+0x1c0/0x1c0 [ 34.260548] [] sk_destruct+0x63/0x80 [ 34.265893] [] __sk_free+0x4f/0x220 [ 34.271191] [] sk_free+0x2b/0x40 [ 34.276195] [] pppol2tp_release+0x239/0x2e0 [ 34.282146] [] sock_release+0x96/0x1c0 [ 34.287660] [] sock_close+0x16/0x20 [ 34.292917] [] __fput+0x263/0x700 [ 34.298008] [] ____fput+0x15/0x20 [ 34.303094] [] task_work_run+0x10c/0x180 [ 34.308795] [] exit_to_usermode_loop+0xfc/0x120 [ 34.315126] [] do_syscall_64+0x364/0x490 [ 34.320814] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.327714] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 34.355154] RIP [] l2tp_session_free+0x11c/0x200 [ 34.361673] RSP [ 34.365280] CR2: 0000000000000080 [ 34.369069] ---[ end trace 45aab8bc37c21506 ]--- [ 34.373820] Kernel panic - not syncing: Fatal exception [ 34.379458] Dumping ftrace buffer: [ 34.382979] (ftrace buffer empty) [ 34.386667] Kernel Offset: disabled [ 34.390267] Rebooting in 86400 seconds..