Commit 8742dc86 authored by Steffen Klassert's avatar Steffen Klassert
Browse files

xfrm4: Fix uninitialized memory read in _decode_session4 



We currently don't reload pointers pointing into skb header
after doing pskb_may_pull() in _decode_session4(). So in case
pskb_may_pull() changed the pointers, we read from random
memory. Fix this by putting all the needed infos on the
stack, so that we don't need to access the header pointers
after doing pskb_may_pull().

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent 025c65e1

net/ipv4/xfrm4_policy.c

+13 −11
Original line number Diff line number Diff line
@@ -111,7 +111,8 @@ static void 
_decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)

{

	const struct iphdr *iph = ip_hdr(skb);

	u8 *xprth = skb_network_header(skb) + iph->ihl * 4;

	int ihl = iph->ihl;

	u8 *xprth = skb_network_header(skb) + ihl * 4;

	struct flowi4 *fl4 = &fl->u.ip4;

	int oif = 0;
@@ -122,6 +123,11 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
	fl4->flowi4_mark = skb->mark;

	fl4->flowi4_oif = reverse ? skb->skb_iif : oif;



	fl4->flowi4_proto = iph->protocol;

	fl4->daddr = reverse ? iph->saddr : iph->daddr;

	fl4->saddr = reverse ? iph->daddr : iph->saddr;

	fl4->flowi4_tos = iph->tos;



	if (!ip_is_fragment(iph)) {

		switch (iph->protocol) {

		case IPPROTO_UDP:
@@ -133,7 +139,7 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
			    pskb_may_pull(skb, xprth + 4 - skb->data)) {

				__be16 *ports;



				xprth = skb_network_header(skb) + iph->ihl * 4;

				xprth = skb_network_header(skb) + ihl * 4;

				ports = (__be16 *)xprth;



				fl4->fl4_sport = ports[!!reverse];
@@ -146,7 +152,7 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
			    pskb_may_pull(skb, xprth + 2 - skb->data)) {

				u8 *icmp;



				xprth = skb_network_header(skb) + iph->ihl * 4;

				xprth = skb_network_header(skb) + ihl * 4;

				icmp = xprth;



				fl4->fl4_icmp_type = icmp[0];
@@ -159,7 +165,7 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
			    pskb_may_pull(skb, xprth + 4 - skb->data)) {

				__be32 *ehdr;



				xprth = skb_network_header(skb) + iph->ihl * 4;

				xprth = skb_network_header(skb) + ihl * 4;

				ehdr = (__be32 *)xprth;



				fl4->fl4_ipsec_spi = ehdr[0];
@@ -171,7 +177,7 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
			    pskb_may_pull(skb, xprth + 8 - skb->data)) {

				__be32 *ah_hdr;



				xprth = skb_network_header(skb) + iph->ihl * 4;

				xprth = skb_network_header(skb) + ihl * 4;

				ah_hdr = (__be32 *)xprth;



				fl4->fl4_ipsec_spi = ah_hdr[1];
@@ -183,7 +189,7 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
			    pskb_may_pull(skb, xprth + 4 - skb->data)) {

				__be16 *ipcomp_hdr;



				xprth = skb_network_header(skb) + iph->ihl * 4;

				xprth = skb_network_header(skb) + ihl * 4;

				ipcomp_hdr = (__be16 *)xprth;



				fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
@@ -196,7 +202,7 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
				__be16 *greflags;

				__be32 *gre_hdr;



				xprth = skb_network_header(skb) + iph->ihl * 4;

				xprth = skb_network_header(skb) + ihl * 4;

				greflags = (__be16 *)xprth;

				gre_hdr = (__be32 *)xprth;
@@ -213,10 +219,6 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
			break;

		}

	}

	fl4->flowi4_proto = iph->protocol;

	fl4->daddr = reverse ? iph->saddr : iph->daddr;

	fl4->saddr = reverse ? iph->daddr : iph->saddr;

	fl4->flowi4_tos = iph->tos;

}



static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,

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