[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.671927] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.484674] random: sshd: uninitialized urandom read (32 bytes read) [ 27.923992] random: sshd: uninitialized urandom read (32 bytes read) [ 28.630143] random: sshd: uninitialized urandom read (32 bytes read) [ 28.762158] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.8' (ECDSA) to the list of known hosts. [ 34.409175] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.605553] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.613770] IP: [] l2tp_session_free+0x11c/0x200 [ 34.620207] PGD 1bbbe2067 [ 34.622884] PUD 1c061b067 PMD 0 [ 34.626362] [ 34.627983] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.632449] Dumping ftrace buffer: [ 34.635978] (ftrace buffer empty) [ 34.639659] Modules linked in: [ 34.642952] CPU: 0 PID: 3814 Comm: syz-executor694 Not tainted 4.9.116-g0137ea2 #70 [ 34.650715] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.660042] task: ffff8801b61b9800 task.stack: ffff8801d9710000 [ 34.666072] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.674918] RSP: 0018:ffff8801d9717ca0 EFLAGS: 00010246 [ 34.680347] RAX: dffffc0000000000 RBX: ffff8801c9e54280 RCX: 0000000000000000 [ 34.687589] RDX: 1ffff100393ca920 RSI: ffffffff836be8f1 RDI: ffff8801c9e54900 [ 34.694833] RBP: ffff8801d9717cc0 R08: ffff8801b61ba0e8 R09: 0000000000000000 [ 34.702078] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9e54780 [ 34.709517] R13: ffff8801c9e54288 R14: 0000000000000000 R15: ffffffff83014be0 [ 34.716762] FS: 00000000016ba880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 34.724973] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.730828] CR2: 0000000000000080 CR3: 00000001bab88000 CR4: 00000000001606f0 [ 34.738075] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 34.745319] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 34.752561] Stack: [ 34.754682] ffff8801d9671100 ffff8801c9e54280 ffff8801d96714d0 ffff8801d96713d8 [ 34.762693] ffff8801d9717ce8 ffffffff836c6202 ffff8801d9671540 ffff8801d9671100 [ 34.770688] ffffffff836c6130 ffff8801d9717d20 ffffffff83022095 ffff8801d9671540 [ 34.778676] Call Trace: [ 34.781242] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.787881] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.794172] [] __sk_destruct+0x55/0x590 [ 34.799776] [] ? sock_release+0x1c0/0x1c0 [ 34.805546] [] sk_destruct+0x63/0x80 [ 34.810883] [] __sk_free+0x4f/0x220 [ 34.816145] [] sk_free+0x2b/0x40 [ 34.821137] [] pppol2tp_release+0x239/0x2e0 [ 34.827085] [] sock_release+0x96/0x1c0 [ 34.832619] [] sock_close+0x16/0x20 [ 34.837873] [] __fput+0x263/0x700 [ 34.842957] [] ____fput+0x15/0x20 [ 34.848035] [] task_work_run+0x10c/0x180 [ 34.853749] [] exit_to_usermode_loop+0xfc/0x120 [ 34.860042] [] do_syscall_64+0x364/0x490 [ 34.865726] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.872633] 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 01 ca fd 4c 89 ea 48 b8 00 [ 34.899530] RIP [] l2tp_session_free+0x11c/0x200 [ 34.906031] RSP [ 34.909626] CR2: 0000000000000080 [ 34.913223] ---[ end trace 384320886e889046 ]--- [ 34.918003] Kernel panic - not syncing: Fatal exception [ 34.923446] Dumping ftrace buffer: [ 34.926974] (ftrace buffer empty) [ 34.930669] Kernel Offset: disabled [ 34.934274] Rebooting in 86400 seconds..