Commit 1a14f1e5 authored by Steffen Klassert's avatar Steffen Klassert
Browse files

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: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent e33d4f13

net/ipv4/xfrm4_policy.c

+10 −5
Original line number Original line Diff line number Diff line
@@ -137,7 +137,8 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
			break;

			break;





		case IPPROTO_ICMP:

		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;

				u8 *icmp = xprth;





				fl4->fl4_icmp_type = icmp[0];

				fl4->fl4_icmp_type = icmp[0];
@@ -146,7 +147,8 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
			break;

			break;





		case IPPROTO_ESP:

		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;

				__be32 *ehdr = (__be32 *)xprth;





				fl4->fl4_ipsec_spi = ehdr[0];

				fl4->fl4_ipsec_spi = ehdr[0];
@@ -154,7 +156,8 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
			break;

			break;





		case IPPROTO_AH:

		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;

				__be32 *ah_hdr = (__be32 *)xprth;





				fl4->fl4_ipsec_spi = ah_hdr[1];

				fl4->fl4_ipsec_spi = ah_hdr[1];
@@ -162,7 +165,8 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 
			break;

			break;





		case IPPROTO_COMP:

		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;

				__be16 *ipcomp_hdr = (__be16 *)xprth;





				fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));

				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;

			break;





		case IPPROTO_GRE:

		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;

				__be16 *greflags = (__be16 *)xprth;

				__be32 *gre_hdr = (__be32 *)xprth;

				__be32 *gre_hdr = (__be32 *)xprth;

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