From 1a14f1e5550a341f76e5c8f596e9b5f8a886dfbc Mon Sep 17 00:00:00 2001 From: Steffen Klassert Date: Fri, 23 Oct 2015 07:31:23 +0200 Subject: [PATCH] xfrm4: Fix header checks in _decode_session4. We skip the header informations if the data pointer points already behind the header in question for some protocols. This is because we call pskb_may_pull with a negative value converted to unsigened int from pskb_may_pull in this case. Skipping the header informations can lead to incorrect policy lookups, so fix it by a check of the data pointer position before we call pskb_may_pull. Signed-off-by: Steffen Klassert --- net/ipv4/xfrm4_policy.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c index 75e8d48c03fb..e4d533c6c796 100644 --- a/net/ipv4/xfrm4_policy.c +++ b/net/ipv4/xfrm4_policy.c @@ -137,7 +137,8 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) break; case IPPROTO_ICMP: - if (pskb_may_pull(skb, xprth + 2 - skb->data)) { + if (xprth + 2 < skb->data || + pskb_may_pull(skb, xprth + 2 - skb->data)) { u8 *icmp = xprth; fl4->fl4_icmp_type = icmp[0]; @@ -146,7 +147,8 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) break; case IPPROTO_ESP: - if (pskb_may_pull(skb, xprth + 4 - skb->data)) { + if (xprth + 4 < skb->data || + pskb_may_pull(skb, xprth + 4 - skb->data)) { __be32 *ehdr = (__be32 *)xprth; fl4->fl4_ipsec_spi = ehdr[0]; @@ -154,7 +156,8 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) break; case IPPROTO_AH: - if (pskb_may_pull(skb, xprth + 8 - skb->data)) { + if (xprth + 8 < skb->data || + pskb_may_pull(skb, xprth + 8 - skb->data)) { __be32 *ah_hdr = (__be32 *)xprth; fl4->fl4_ipsec_spi = ah_hdr[1]; @@ -162,7 +165,8 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) break; case IPPROTO_COMP: - if (pskb_may_pull(skb, xprth + 4 - skb->data)) { + if (xprth + 4 < skb->data || + pskb_may_pull(skb, xprth + 4 - skb->data)) { __be16 *ipcomp_hdr = (__be16 *)xprth; fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1])); @@ -170,7 +174,8 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) break; case IPPROTO_GRE: - if (pskb_may_pull(skb, xprth + 12 - skb->data)) { + if (xprth + 12 < skb->data || + pskb_may_pull(skb, xprth + 12 - skb->data)) { __be16 *greflags = (__be16 *)xprth; __be32 *gre_hdr = (__be32 *)xprth; -- 2.20.1