From: Laura Garcia Liebana <nevola@gmail.com>
Date: Tue, 9 Aug 2016 18:46:16 +0000 (+0200)
Subject: netfilter: nft_exthdr: Add size check on u8 nft_exthdr attributes
X-Git-Tag: v3.16.40~243
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=aaf2bb422c25859fad0a66fb722bc47866004ab8;p=thirdparty%2Fkernel%2Fstable.git

netfilter: nft_exthdr: Add size check on u8 nft_exthdr attributes

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>
---

diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index 55c939f5371fa..c04e91c5c78ea 100644
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -59,6 +59,7 @@ static int nft_exthdr_init(const struct nft_ctx *ctx,
 {
 	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 nft_ctx *ctx,
 	    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;