On Wed, Jun 18, 2014 at 11:44:01AM +0200, Pablo Neira Ayuso wrote:
> From: Peter Christensen <[email protected]>
>
> [ Upstream commit f44a5f45f544561302e855e7bd104e5f506ec01b ]
Thank you, I'm queuing this for the 3.11 kernel as well.
Cheers,
--
Luís
>
> 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 f2edb9f7706dcb2c0d9a362b2ba849efe3a97f5e ("ipvs: implement
> passive PMTUD for IPIP packets").
>
> Cc: <[email protected]> # 3.10.x
> Cc: <[email protected]> # 3.12.x
> Cc: <[email protected]> # 3.14.x
> Signed-off-by: Peter Christensen <[email protected]>
> Acked-by: Julian Anastasov <[email protected]>
> Signed-off-by: Simon Horman <[email protected]>
> ---
> net/netfilter/ipvs/ip_vs_core.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index 4f26ee4..3d2d2c8 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c
> @@ -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);
>
> --
> 1.7.10.4
>
> --
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