From: Dave Watson
Date: Mon, 26 Jun 2017 08:36:47 -0700
> If icsk_ulp_ops is unset, it dereferences a null ptr.
> Add a null ptr check.
>
> BUG: KASAN: null-ptr-deref in copy_to_user include/linux/uaccess.h:168
> [inline]
> BUG: KASAN: null-ptr-deref in do_tcp_getsockopt.isra.33+0x24f/0x1e30
>
If icsk_ulp_ops is unset, it dereferences a null ptr.
Add a null ptr check.
BUG: KASAN: null-ptr-deref in copy_to_user include/linux/uaccess.h:168 [inline]
BUG: KASAN: null-ptr-deref in do_tcp_getsockopt.isra.33+0x24f/0x1e30
net/ipv4/tcp.c:3057
Read of size 4 at addr 0020 by task syz-