[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.549246] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 16.669829] random: sshd: uninitialized urandom read (32 bytes read) [ 17.099066] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.872007] random: sshd: uninitialized urandom read (32 bytes read) [ 18.021947] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.47' (ECDSA) to the list of known hosts. [ 23.539336] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.748600] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.756919] IP: [] l2tp_session_free+0x11c/0x200 [ 23.763370] PGD 1bb539067 [ 23.766026] PUD 1bb4b3067 PMD 0 [ 23.769628] [ 23.771269] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.775753] Dumping ftrace buffer: [ 23.779293] (ftrace buffer empty) [ 23.782992] Modules linked in: [ 23.786309] CPU: 1 PID: 3778 Comm: syz-executor571 Not tainted 4.9.120-gf85543b #76 [ 23.794140] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.803508] task: ffff8801bb8e6000 task.stack: ffff8801b99a8000 [ 23.809745] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.818822] RSP: 0018:ffff8801b99afca0 EFLAGS: 00010246 [ 23.824258] RAX: dffffc0000000000 RBX: ffff8801ba7dd680 RCX: 0000000000000000 [ 23.831936] RDX: 1ffff1003924b120 RSI: ffffffff836c29a1 RDI: ffff8801c9258900 [ 23.839201] RBP: ffff8801b99afcc0 R08: ffff8801bb8e68e8 R09: 0000000000000000 [ 23.846576] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9258780 [ 23.853932] R13: ffff8801ba7dd688 R14: 0000000000000000 R15: ffffffff83018be0 [ 23.861328] FS: 0000000001877880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 23.869545] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.875609] CR2: 0000000000000080 CR3: 00000001c0fa8000 CR4: 00000000001606f0 [ 23.882893] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.890213] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.897475] Stack: [ 23.899681] ffff8801ba34bb80 ffff8801ba7dd680 ffff8801ba34bf50 ffff8801ba34be58 [ 23.907835] ffff8801b99afce8 ffffffff836ca2b2 ffff8801ba34bfc0 ffff8801ba34bb80 [ 23.915971] ffffffff836ca1e0 ffff8801b99afd20 ffffffff830260f5 ffff8801ba34bfc0 [ 23.924111] Call Trace: [ 23.926694] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.933355] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.939671] [] __sk_destruct+0x55/0x590 [ 23.945319] [] ? sock_release+0x1c0/0x1c0 [ 23.951132] [] sk_destruct+0x63/0x80 [ 23.956530] [] __sk_free+0x4f/0x220 [ 23.961815] [] sk_free+0x2b/0x40 [ 23.966850] [] pppol2tp_release+0x239/0x2e0 [ 23.972817] [] sock_release+0x96/0x1c0 [ 23.978345] [] sock_close+0x16/0x20 [ 23.983618] [] __fput+0x263/0x700 [ 23.988711] [] ____fput+0x15/0x20 [ 23.993804] [] task_work_run+0x10c/0x180 [ 23.999507] [] exit_to_usermode_loop+0xfc/0x120 [ 24.005991] [] do_syscall_64+0x364/0x490 [ 24.011757] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.018671] 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 15 de c9 fd 4c 89 ea 48 b8 00 [ 24.046954] RIP [] l2tp_session_free+0x11c/0x200 [ 24.053502] RSP [ 24.057113] CR2: 0000000000000080 [ 24.060905] ---[ end trace f8adb8102d990921 ]--- [ 24.065697] Kernel panic - not syncing: Fatal exception [ 24.071623] Dumping ftrace buffer: [ 24.075187] (ftrace buffer empty) [ 24.078885] Kernel Offset: disabled [ 24.082501] Rebooting in 86400 seconds..