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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>
This commit is contained in:
Steffen Klassert 2015-10-23 07:31:23 +02:00
parent e33d4f13d2
commit 1a14f1e555
1 changed files with 10 additions and 5 deletions
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15
net/ipv4/xfrm4_policy.c
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@ -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;