[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.359724] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 12.904366] random: sshd: uninitialized urandom read (32 bytes read) [ 13.035924] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 [ 13.547399] random: sshd: uninitialized urandom read (32 bytes read) syzkaller login: [ 28.401719] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.28' (ECDSA) to the list of known hosts. [ 33.865121] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.060747] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.069229] IP: [] l2tp_session_free+0x11c/0x200 [ 34.076082] PGD 1c19e8067 [ 34.078872] PUD 1c19ed067 PMD 0 [ 34.082707] [ 34.084477] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.089218] Dumping ftrace buffer: [ 34.092910] (ftrace buffer empty) [ 34.096834] Modules linked in: [ 34.100475] CPU: 0 PID: 3811 Comm: syz-executor113 Not tainted 4.9.119-g9dc978d #75 [ 34.108570] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.118331] task: ffff8801b7aa9800 task.stack: ffff8801b5dd8000 [ 34.124756] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.133916] RSP: 0018:ffff8801b5ddfca0 EFLAGS: 00010246 [ 34.139852] RAX: dffffc0000000000 RBX: ffff8801c9cb7680 RCX: 0000000000000000 [ 34.147368] RDX: 1ffff100393ddeb0 RSI: ffffffff836bf9a1 RDI: ffff8801c9eef580 [ 34.155018] RBP: ffff8801b5ddfcc0 R08: ffff8801b7aaa0e8 R09: 0000000000000000 [ 34.162543] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9eef400 [ 34.170034] R13: ffff8801c9cb7688 R14: 0000000000000000 R15: ffffffff83015be0 [ 34.177747] FS: 0000000002053880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 34.186193] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.192705] CR2: 0000000000000080 CR3: 00000001be574000 CR4: 00000000001606f0 [ 34.200248] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 34.207645] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 34.215351] Stack: [ 34.217499] ffff8801d95d1980 ffff8801c9cb7680 ffff8801d95d1d50 ffff8801d95d1c58 [ 34.225788] ffff8801b5ddfce8 ffffffff836c72b2 ffff8801d95d1dc0 ffff8801d95d1980 [ 34.234227] ffffffff836c71e0 ffff8801b5ddfd20 ffffffff830230f5 ffff8801d95d1dc0 [ 34.242645] Call Trace: [ 34.245365] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.252481] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.258940] [] __sk_destruct+0x55/0x590 [ 34.264887] [] ? sock_release+0x1c0/0x1c0 [ 34.270817] [] sk_destruct+0x63/0x80 [ 34.276553] [] __sk_free+0x4f/0x220 [ 34.281830] [] sk_free+0x2b/0x40 [ 34.286867] [] pppol2tp_release+0x239/0x2e0 [ 34.292839] [] sock_release+0x96/0x1c0 [ 34.298371] [] sock_close+0x16/0x20 [ 34.303652] [] __fput+0x263/0x700 [ 34.308749] [] ____fput+0x15/0x20 [ 34.313845] [] task_work_run+0x10c/0x180 [ 34.319743] [] exit_to_usermode_loop+0xfc/0x120 [ 34.326055] [] do_syscall_64+0x364/0x490 [ 34.331761] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.338823] 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 [ 34.367248] RIP [] l2tp_session_free+0x11c/0x200 [ 34.373784] RSP [ 34.377748] CR2: 0000000000000080 [ 34.381620] ---[ end trace 9fc0d6e5b94bbbe9 ]--- [ 34.386383] Kernel panic - not syncing: Fatal exception [ 34.392447] Dumping ftrace buffer: [ 34.395987] (ftrace buffer empty) [ 34.399686] Kernel Offset: disabled [ 34.403463] Rebooting in 86400 seconds..