[PATCH 3.16 063/306] netfilter: nft_exthdr: Add size check on u8 nft_exthdr attributes

Ben Hutchings
2017-02-15T23:23:53Z

From: Laura Garcia Liebana <nevola@gmail.com>

commit 4da449ae1df9cfeb167e78f250b250eff64bc65e upstream.

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>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/netfilter/nft_exthdr.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -59,6 +59,7 @@ static int nft_exthdr_init(const struct
{
struct nft_exthdr *priv = nft_expr_priv(expr);
int err;
+ u32 offset, len;

if (tb[NFTA_EXTHDR_DREG] == NULL ||
tb[NFTA_EXTHDR_TYPE] == NULL ||
@@ -66,9 +67,15 @@ static int nft_exthdr_init(const struct
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;
if (priv->len == 0 ||
priv->len > FIELD_SIZEOF(struct nft_data, data))
return -EINVAL;