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Commit f44a5f45 authored by Peter Christensen's avatar Peter Christensen Committed by Simon Horman
Browse files

ipvs: Fix panic due to non-linear skb 



Receiving a ICMP response to an IPIP packet in a non-linear skb could
cause a kernel panic in __skb_pull.

The problem was introduced in
commit f2edb9f7 ("ipvs: implement
passive PMTUD for IPIP packets").

Signed-off-by: default avatarPeter Christensen <pch@ordbogen.com>
Acked-by: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarSimon Horman <horms@verge.net.au>
parent 3b084e99

net/netfilter/ipvs/ip_vs_core.c

+10 −5
Original line number Original line Diff line number Diff line
@@ -1392,15 +1392,19 @@ ip_vs_in_icmp(struct sk_buff *skb, int *related, unsigned int hooknum) 




	if (ipip) {

	if (ipip) {

		__be32 info = ic->un.gateway;

		__be32 info = ic->un.gateway;

		__u8 type = ic->type;

		__u8 code = ic->code;





		/* Update the MTU */

		/* Update the MTU */

		if (ic->type == ICMP_DEST_UNREACH &&

		if (ic->type == ICMP_DEST_UNREACH &&

		    ic->code == ICMP_FRAG_NEEDED) {

		    ic->code == ICMP_FRAG_NEEDED) {

			struct ip_vs_dest *dest = cp->dest;

			struct ip_vs_dest *dest = cp->dest;

			u32 mtu = ntohs(ic->un.frag.mtu);

			u32 mtu = ntohs(ic->un.frag.mtu);

			__be16 frag_off = cih->frag_off;





			/* Strip outer IP and ICMP, go to IPIP header */

			/* Strip outer IP and ICMP, go to IPIP header */

			__skb_pull(skb, ihl + sizeof(_icmph));

			if (pskb_pull(skb, ihl + sizeof(_icmph)) == NULL)

				goto ignore_ipip;

			offset2 -= ihl + sizeof(_icmph);

			offset2 -= ihl + sizeof(_icmph);

			skb_reset_network_header(skb);

			skb_reset_network_header(skb);

			IP_VS_DBG(12, "ICMP for IPIP %pI4->%pI4: mtu=%u\n",

			IP_VS_DBG(12, "ICMP for IPIP %pI4->%pI4: mtu=%u\n",
@@ -1408,7 +1412,7 @@ ip_vs_in_icmp(struct sk_buff *skb, int *related, unsigned int hooknum) 
			ipv4_update_pmtu(skb, dev_net(skb->dev),

			ipv4_update_pmtu(skb, dev_net(skb->dev),

					 mtu, 0, 0, 0, 0);

					 mtu, 0, 0, 0, 0);

			/* Client uses PMTUD? */

			/* Client uses PMTUD? */

			if (!(cih->frag_off & htons(IP_DF)))

			if (!(frag_off & htons(IP_DF)))

				goto ignore_ipip;

				goto ignore_ipip;

			/* Prefer the resulting PMTU */

			/* Prefer the resulting PMTU */

			if (dest) {

			if (dest) {
@@ -1427,12 +1431,13 @@ ip_vs_in_icmp(struct sk_buff *skb, int *related, unsigned int hooknum) 
		/* Strip outer IP, ICMP and IPIP, go to IP header of

		/* Strip outer IP, ICMP and IPIP, go to IP header of

		 * original request.

		 * original request.

		 */

		 */

		__skb_pull(skb, offset2);

		if (pskb_pull(skb, offset2) == NULL)

			goto ignore_ipip;

		skb_reset_network_header(skb);

		skb_reset_network_header(skb);

		IP_VS_DBG(12, "Sending ICMP for %pI4->%pI4: t=%u, c=%u, i=%u\n",

		IP_VS_DBG(12, "Sending ICMP for %pI4->%pI4: t=%u, c=%u, i=%u\n",

			&ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,

			&ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,

			ic->type, ic->code, ntohl(info));

			type, code, ntohl(info));

		icmp_send(skb, ic->type, ic->code, info);

		icmp_send(skb, type, code, info);

		/* ICMP can be shorter but anyways, account it */

		/* ICMP can be shorter but anyways, account it */

		ip_vs_out_stats(cp, skb);

		ip_vs_out_stats(cp, skb);