From 1a14f1e5550a341f76e5c8f596e9b5f8a886dfbc Mon Sep 17 00:00:00 2001
From: Steffen Klassert <steffen.klassert@secunet.com>
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 <steffen.klassert@secunet.com>
---
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 75e8d48c03fb1..e4d533c6c7963 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;