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Subject[PATCH 3.16 062/157] xfrm4: Reload skb header pointers after calling pskb_may_pull.
3.16.72-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Steffen Klassert <steffen.klassert@secunet.com>

commit ea673a4d3a337184f3c314dcc6300bf02f39e077 upstream.

A call to pskb_may_pull may change the pointers into the packet,
so reload the pointers after the call.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/ipv4/xfrm4_policy.c | 33 ++++++++++++++++++++++++++-------
1 file changed, 26 insertions(+), 7 deletions(-)

--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -123,7 +123,10 @@ _decode_session4(struct sk_buff *skb, st
case IPPROTO_DCCP:
if (xprth + 4 < skb->data ||
pskb_may_pull(skb, xprth + 4 - skb->data)) {
- __be16 *ports = (__be16 *)xprth;
+ __be16 *ports;
+
+ xprth = skb_network_header(skb) + iph->ihl * 4;
+ ports = (__be16 *)xprth;

fl4->fl4_sport = ports[!!reverse];
fl4->fl4_dport = ports[!reverse];
@@ -133,7 +136,10 @@ _decode_session4(struct sk_buff *skb, st
case IPPROTO_ICMP:
if (xprth + 2 < skb->data ||
pskb_may_pull(skb, xprth + 2 - skb->data)) {
- u8 *icmp = xprth;
+ u8 *icmp;
+
+ xprth = skb_network_header(skb) + iph->ihl * 4;
+ icmp = xprth;

fl4->fl4_icmp_type = icmp[0];
fl4->fl4_icmp_code = icmp[1];
@@ -143,7 +149,10 @@ _decode_session4(struct sk_buff *skb, st
case IPPROTO_ESP:
if (xprth + 4 < skb->data ||
pskb_may_pull(skb, xprth + 4 - skb->data)) {
- __be32 *ehdr = (__be32 *)xprth;
+ __be32 *ehdr;
+
+ xprth = skb_network_header(skb) + iph->ihl * 4;
+ ehdr = (__be32 *)xprth;

fl4->fl4_ipsec_spi = ehdr[0];
}
@@ -152,7 +161,10 @@ _decode_session4(struct sk_buff *skb, st
case IPPROTO_AH:
if (xprth + 8 < skb->data ||
pskb_may_pull(skb, xprth + 8 - skb->data)) {
- __be32 *ah_hdr = (__be32 *)xprth;
+ __be32 *ah_hdr;
+
+ xprth = skb_network_header(skb) + iph->ihl * 4;
+ ah_hdr = (__be32 *)xprth;

fl4->fl4_ipsec_spi = ah_hdr[1];
}
@@ -161,7 +173,10 @@ _decode_session4(struct sk_buff *skb, st
case IPPROTO_COMP:
if (xprth + 4 < skb->data ||
pskb_may_pull(skb, xprth + 4 - skb->data)) {
- __be16 *ipcomp_hdr = (__be16 *)xprth;
+ __be16 *ipcomp_hdr;
+
+ xprth = skb_network_header(skb) + iph->ihl * 4;
+ ipcomp_hdr = (__be16 *)xprth;

fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
}
@@ -170,8 +185,12 @@ _decode_session4(struct sk_buff *skb, st
case IPPROTO_GRE:
if (xprth + 12 < skb->data ||
pskb_may_pull(skb, xprth + 12 - skb->data)) {
- __be16 *greflags = (__be16 *)xprth;
- __be32 *gre_hdr = (__be32 *)xprth;
+ __be16 *greflags;
+ __be32 *gre_hdr;
+
+ xprth = skb_network_header(skb) + iph->ihl * 4;
+ greflags = (__be16 *)xprth;
+ gre_hdr = (__be32 *)xprth;

if (greflags[0] & GRE_KEY) {
if (greflags[0] & GRE_CSUM)
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