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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 f2edb9f770 ("ipvs: implement
passive PMTUD for IPIP packets").

Signed-off-by: Peter Christensen <pch@ordbogen.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
This commit is contained in:
Peter Christensen 2014-05-24 21:40:12 +02:00 committed by Simon Horman
parent 3b084e99a3
commit f44a5f45f5
1 changed files with 10 additions and 5 deletions
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15
net/netfilter/ipvs/ip_vs_core.c
View File

@ -1392,15 +1392,19 @@ ip_vs_in_icmp(struct sk_buff *skb, int *related, unsigned int hooknum)
if (ipip) {
__be32 info = ic->un.gateway;
__u8 type = ic->type;
__u8 code = ic->code;
/* Update the MTU */
if (ic->type == ICMP_DEST_UNREACH &&
ic->code == ICMP_FRAG_NEEDED) {
struct ip_vs_dest *dest = cp->dest;
u32 mtu = ntohs(ic->un.frag.mtu);
__be16 frag_off = cih->frag_off;
/* 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);
skb_reset_network_header(skb);
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),
mtu, 0, 0, 0, 0);
/* Client uses PMTUD? */
if (!(cih->frag_off & htons(IP_DF)))
if (!(frag_off & htons(IP_DF)))
goto ignore_ipip;
/* Prefer the resulting PMTU */
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
* original request.
*/
__skb_pull(skb, offset2);
if (pskb_pull(skb, offset2) == NULL)
goto ignore_ipip;
skb_reset_network_header(skb);
IP_VS_DBG(12, "Sending ICMP for %pI4->%pI4: t=%u, c=%u, i=%u\n",
&ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
ic->type, ic->code, ntohl(info));
icmp_send(skb, ic->type, ic->code, info);
type, code, ntohl(info));
icmp_send(skb, type, code, info);
/* ICMP can be shorter but anyways, account it */
ip_vs_out_stats(cp, skb);