netfilter: nft_exthdr: Add size check on u8 nft_exthdr attributes
Fix the direct assignment of offset and length attributes included in
nft_exthdr structure from u32 data to u8.
Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index ba7aed1..82c264e 100644
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -59,6 +59,7 @@
const struct nlattr * const tb[])
{
struct nft_exthdr *priv = nft_expr_priv(expr);
+ u32 offset, len;
if (tb[NFTA_EXTHDR_DREG] == NULL ||
tb[NFTA_EXTHDR_TYPE] == NULL ||
@@ -66,9 +67,15 @@
tb[NFTA_EXTHDR_LEN] == NULL)
return -EINVAL;
+ offset = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OFFSET]));
+ len = ntohl(nla_get_be32(tb[NFTA_EXTHDR_LEN]));
+
+ if (offset > U8_MAX || len > U8_MAX)
+ return -ERANGE;
+
priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
- priv->offset = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OFFSET]));
- priv->len = ntohl(nla_get_be32(tb[NFTA_EXTHDR_LEN]));
+ priv->offset = offset;
+ priv->len = len;
priv->dreg = nft_parse_register(tb[NFTA_EXTHDR_DREG]);
return nft_validate_register_store(ctx, priv->dreg, NULL,