net: sock: validate data_len before allocating skb in sock_alloc_send_pskb()

We need to validate the number of pages consumed by data_len, otherwise frags
array could be overflowed by userspace. So this patch validate data_len and
return -EMSGSIZE when data_len may occupies more frags than MAX_SKB_FRAGS.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
void proto_unregister(struct proto *prot)
{
	mutex_lock(&proto_list_mutex);
	release_proto_idx(prot);
	list_del(&prot->node);
	mutex_unlock(&proto_list_mutex);

	if (prot->slab != NULL) {
		kmem_cache_destroy(prot->slab);
		prot->slab = NULL;
	}

	if (prot->rsk_prot != NULL && prot->rsk_prot->slab != NULL) {
		kmem_cache_destroy(prot->rsk_prot->slab);
		kfree(prot->rsk_prot->slab_name);
		prot->rsk_prot->slab = NULL;
	}

	if (prot->twsk_prot != NULL && prot->twsk_prot->twsk_slab != NULL) {
		kmem_cache_destroy(prot->twsk_prot->twsk_slab);
		kfree(prot->twsk_prot->twsk_slab_name);
		prot->twsk_prot->twsk_slab = NULL;
	}
}

void proto_unregister(struct proto *prot)
{
	mutex_lock(&proto_list_mutex);
	release_proto_idx(prot);
	list_del(&prot->node);
	mutex_unlock(&proto_list_mutex);

	if (prot->slab != NULL) {
		kmem_cache_destroy(prot->slab);
		prot->slab = NULL;
	}

	if (prot->rsk_prot != NULL && prot->rsk_prot->slab != NULL) {
		kmem_cache_destroy(prot->rsk_prot->slab);
		kfree(prot->rsk_prot->slab_name);
		prot->rsk_prot->slab = NULL;
	}

	if (prot->twsk_prot != NULL && prot->twsk_prot->twsk_slab != NULL) {
		kmem_cache_destroy(prot->twsk_prot->twsk_slab);
		kfree(prot->twsk_prot->twsk_slab_name);
		prot->twsk_prot->twsk_slab = NULL;
	}
}
