netfilter: nf_tables_offload: check for register data length mismatches

Make sure register data length does not mismatch immediate data length,
otherwise hit EOPNOTSUPP.

Fixes: c9626a2c ("netfilter: nf_tables: add hardware offload support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_bitwise.c

@@ -134,12 +134,13 @@ static int nft_bitwise_offload(struct nft_offload_ctx *ctx,
                                const struct nft_expr *expr)
 {
 	const struct nft_bitwise *priv = nft_expr_priv(expr);
+	struct nft_offload_reg *reg = &ctx->regs[priv->dreg];
 
 	if (memcmp(&priv->xor, &zero, sizeof(priv->xor)) ||
-	    priv->sreg != priv->dreg)
+	    priv->sreg != priv->dreg || priv->len != reg->len)
 		return -EOPNOTSUPP;
 
-	memcpy(&ctx->regs[priv->dreg].mask, &priv->mask, sizeof(priv->mask));
+	memcpy(&reg->mask, &priv->mask, sizeof(priv->mask));
 
 	return 0;
 }

net/netfilter/nft_cmp.c

@@ -116,7 +116,7 @@ static int __nft_cmp_offload(struct nft_offload_ctx *ctx,
 	u8 *mask = (u8 *)&flow->match.mask;
 	u8 *key = (u8 *)&flow->match.key;
 
-	if (priv->op != NFT_CMP_EQ)
+	if (priv->op != NFT_CMP_EQ || reg->len != priv->len)
 		return -EOPNOTSUPP;
 
 	memcpy(key + reg->offset, &priv->data, priv->len);