Re: [PATCH v2 net-next] fix unsafe set_memory_rw from softirq

[Eric Dumazet]

On Thu, 2013-10-03 at 15:47 -0700, Alexei Starovoitov wrote:

> @@ -722,7 +725,8 @@ EXPORT_SYMBOL_GPL(sk_unattached_filter_destroy);
>  int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
>  {
>  	struct sk_filter *fp, *old_fp;
> -	unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
> +	unsigned int fsize = max(sizeof(struct sock_filter) * fprog->len,
> +				 sizeof(struct work_struct));
>  	int err;
>  
>  	if (sock_flag(sk, SOCK_FILTER_LOCKED))

Thats broken, as we might copy more data from user than expected,
and eventually trigger EFAULT :

if (copy_from_user(fp->insns, fprog->filter, fsize)) {


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