[PATCH v3 net-next] fix unsafe set_memory_rw from softirq

[Alexei Starovoitov]

On Thu, Oct 3, 2013 at 10:16 PM, Eric Dumazet <eric.dumazet at gmail.com> wrote:
> On Thu, 2013-10-03 at 21:11 -0700, Alexei Starovoitov wrote:
>
> -static inline unsigned int sk_filter_len(const struct sk_filter *fp)
> +static inline unsigned int sk_filter_size(const struct sk_filter *fp,
> +                                         unsigned int proglen)
>  {
> -       return fp->len * sizeof(struct sock_filter) + sizeof(*fp);
> +       return max(sizeof(*fp),
> +                  offsetof(struct sk_filter, insns[proglen]));
>  }

indeed that's cleaner.
Like this then:
-static inline unsigned int sk_filter_len(const struct sk_filter *fp)
+static inline unsigned int sk_filter_size(unsigned int proglen)
 {
-       return fp->len * sizeof(struct sock_filter) + sizeof(*fp);
+       return max(sizeof(struct sk_filter),
+                  offsetof(struct sk_filter, insns[proglen]));
 }

testing it... will send v4 shortly