[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.554378] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 13.694393] random: sshd: uninitialized urandom read (32 bytes read) [ 13.902687] random: sshd: uninitialized urandom read (32 bytes read) [ 14.703124] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.862148] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.11' (ECDSA) to the list of known hosts. [ 20.452500] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 20.655128] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 20.663555] IP: [] l2tp_session_free+0x11c/0x200 [ 20.670072] PGD 1b6c29067 [ 20.672847] PUD 1bbd9b067 PMD 0 [ 20.676379] [ 20.678012] Oops: 0002 [#1] PREEMPT SMP KASAN [ 20.682494] Dumping ftrace buffer: [ 20.686039] (ftrace buffer empty) [ 20.689737] Modules linked in: [ 20.693045] CPU: 0 PID: 3793 Comm: syz-executor728 Not tainted 4.9.120-gf85543b #76 [ 20.700852] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 20.710200] task: ffff8801b6ba1800 task.stack: ffff8801b5f38000 [ 20.716242] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 20.725141] RSP: 0018:ffff8801b5f3fca0 EFLAGS: 00010246 [ 20.730737] RAX: dffffc0000000000 RBX: ffff8801b58d2000 RCX: 0000000000000000 [ 20.737994] RDX: 1ffff10036d5e9c0 RSI: ffffffff836c29a1 RDI: ffff8801b6af4e00 [ 20.745252] RBP: ffff8801b5f3fcc0 R08: ffff8801b6ba20e8 R09: 0000000000000000 [ 20.752506] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6af4c80 [ 20.759763] R13: ffff8801b58d2008 R14: 0000000000000000 R15: ffffffff83018be0 [ 20.767151] FS: 000000000071e880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 20.775414] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 20.781282] CR2: 0000000000000080 CR3: 00000001b9820000 CR4: 00000000001606f0 [ 20.788594] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 20.795851] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 20.803105] Stack: [ 20.805242] ffff8801b5869100 ffff8801b58d2000 ffff8801b58694d0 ffff8801b58693d8 [ 20.813295] ffff8801b5f3fce8 ffffffff836ca2b2 ffff8801b5869540 ffff8801b5869100 [ 20.821357] ffffffff836ca1e0 ffff8801b5f3fd20 ffffffff830260f5 ffff8801b5869540 [ 20.829406] Call Trace: [ 20.831986] [] pppol2tp_session_destruct+0xd2/0x110 [ 20.838640] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 20.844978] [] __sk_destruct+0x55/0x590 [ 20.850609] [] ? sock_release+0x1c0/0x1c0 [ 20.856408] [] sk_destruct+0x63/0x80 [ 20.861764] [] __sk_free+0x4f/0x220 [ 20.867027] [] sk_free+0x2b/0x40 [ 20.872027] [] pppol2tp_release+0x239/0x2e0 [ 20.877982] [] sock_release+0x96/0x1c0 [ 20.883503] [] sock_close+0x16/0x20 [ 20.888771] [] __fput+0x263/0x700 [ 20.893867] [] ____fput+0x15/0x20 [ 20.898958] [] task_work_run+0x10c/0x180 [ 20.904681] [] exit_to_usermode_loop+0xfc/0x120 [ 20.911041] [] do_syscall_64+0x364/0x490 [ 20.916744] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 20.923653] 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 [ 20.951773] RIP [] l2tp_session_free+0x11c/0x200 [ 20.958303] RSP [ 20.962058] CR2: 0000000000000080 [ 20.967727] ---[ end trace ff68325148e30600 ]--- [ 20.972493] Kernel panic - not syncing: Fatal exception [ 20.978315] Dumping ftrace buffer: [ 20.981850] (ftrace buffer empty) [ 20.985543] Kernel Offset: disabled [ 20.989153] Rebooting in 86400 seconds..