[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.739961] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.361952] random: sshd: uninitialized urandom read (32 bytes read) [ 23.586737] random: sshd: uninitialized urandom read (32 bytes read) [ 24.480749] random: sshd: uninitialized urandom read (32 bytes read) [ 41.649216] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.8' (ECDSA) to the list of known hosts. [ 47.145706] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 47.341421] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 47.349658] IP: [] l2tp_session_free+0x11c/0x200 [ 47.356092] PGD 1bf7a9067 [ 47.358737] PUD 1c08cf067 PMD 0 [ 47.362241] [ 47.363872] Oops: 0002 [#1] PREEMPT SMP KASAN [ 47.368356] Dumping ftrace buffer: [ 47.371871] (ftrace buffer empty) [ 47.375565] Modules linked in: [ 47.378871] CPU: 1 PID: 3812 Comm: syz-executor778 Not tainted 4.9.113-g8956c50 #67 [ 47.386642] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 47.396011] task: ffff8801d9613000 task.stack: ffff8801d9750000 [ 47.402061] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 47.411361] RSP: 0018:ffff8801d9757ca0 EFLAGS: 00010246 [ 47.416795] RAX: dffffc0000000000 RBX: ffff8801c824ac80 RCX: 0000000000000000 [ 47.424045] RDX: 1ffff10036e01d20 RSI: ffffffff836bcee1 RDI: ffff8801b700e900 [ 47.431304] RBP: ffff8801d9757cc0 R08: ffff8801d96138e8 R09: 0000000000000000 [ 47.438559] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b700e780 [ 47.445811] R13: ffff8801c824ac88 R14: 0000000000000000 R15: ffffffff83013be0 [ 47.453064] FS: 0000000000fd0880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 47.461276] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 47.467138] CR2: 0000000000000080 CR3: 00000001bc167000 CR4: 00000000001606f0 [ 47.474390] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 47.481642] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 47.488888] Stack: [ 47.491019] ffff8801d8ed9100 ffff8801c824ac80 ffff8801d8ed94d0 ffff8801d8ed93d8 [ 47.499066] ffff8801d9757ce8 ffffffff836c47f2 ffff8801d8ed9540 ffff8801d8ed9100 [ 47.507087] ffffffff836c4720 ffff8801d9757d20 ffffffff83021095 ffff8801d8ed9540 [ 47.515111] Call Trace: [ 47.517683] [] pppol2tp_session_destruct+0xd2/0x110 [ 47.524416] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 47.530715] [] __sk_destruct+0x55/0x590 [ 47.536329] [] ? sock_release+0x1c0/0x1c0 [ 47.542108] [] sk_destruct+0x63/0x80 [ 47.547449] [] __sk_free+0x4f/0x220 [ 47.552710] [] sk_free+0x2b/0x40 [ 47.557705] [] pppol2tp_release+0x239/0x2e0 [ 47.563675] [] sock_release+0x96/0x1c0 [ 47.569190] [] sock_close+0x16/0x20 [ 47.574450] [] __fput+0x263/0x700 [ 47.579536] [] ____fput+0x15/0x20 [ 47.584620] [] task_work_run+0x10c/0x180 [ 47.590308] [] exit_to_usermode_loop+0xfc/0x120 [ 47.596696] [] do_syscall_64+0x364/0x490 [ 47.602399] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 47.609303] 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 1b ca fd 4c 89 ea 48 b8 00 [ 47.636873] RIP [] l2tp_session_free+0x11c/0x200 [ 47.643400] RSP [ 47.647004] CR2: 0000000000000080 [ 47.650813] ---[ end trace c99cc3fd87aebe1a ]--- [ 47.655591] Kernel panic - not syncing: Fatal exception [ 47.661340] Dumping ftrace buffer: [ 47.664861] (ftrace buffer empty) [ 47.668553] Kernel Offset: disabled [ 47.672178] Rebooting in 86400 seconds..