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-rw-r--r--net/ipv6/exthdrs.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index c486b8e1817f..aa0a51e64682 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -153,6 +153,7 @@ static int ip6_parse_tlv(struct tlvtype_proc *procs, struct sk_buff *skb)
while (len > 0) {
int optlen = nh[off + 1] + 2;
+ int i;
switch (nh[off]) {
case IPV6_TLV_PAD0:
@@ -160,6 +161,21 @@ static int ip6_parse_tlv(struct tlvtype_proc *procs, struct sk_buff *skb)
break;
case IPV6_TLV_PADN:
+ /* RFC 2460 states that the purpose of PadN is
+ * to align the containing header to multiples
+ * of 8. 7 is therefore the highest valid value.
+ * See also RFC 4942, Section 2.1.9.5.
+ */
+ if (optlen > 7)
+ goto bad;
+ /* RFC 4942 recommends receiving hosts to
+ * actively check PadN payload to contain
+ * only zeroes.
+ */
+ for (i = 2; i < optlen; i++) {
+ if (nh[off + i] != 0)
+ goto bad;
+ }
break;
default: /* Other TLV code so scan list */