From: Bjorn Helgaas <bhelg...@google.com> Date: Fri, 15 Nov 2013 15:29:53 -0700
> [+cc David, Eric, Alex, netdev] > > Alex reported a similar issue at > http://marc.info/?l=linux-netdev&m=138355719901790&w=4 Fixed by: commit 84502b5ef9849a9694673b15c31bd3ac693010ae Author: Steffen Klassert <steffen.klass...@secunet.com> Date: Wed Oct 30 11:16:28 2013 +0100 xfrm: Fix null pointer dereference when decoding sessions On some codepaths the skb does not have a dst entry when xfrm_decode_session() is called. So check for a valid skb_dst() before dereferencing the device interface index. We use 0 as the device index if there is no valid skb_dst(), or at reverse decoding we use skb_iif as device interface index. Bug was introduced with git commit bafd4bd4dc ("xfrm: Decode sessions with output interface."). Reported-by: Meelis Roos <mr...@linux.ee> Tested-by: Meelis Roos <mr...@linux.ee> Signed-off-by: Steffen Klassert <steffen.klass...@secunet.com> diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c index 4764ee4..e1a6393 100644 --- a/net/ipv4/xfrm4_policy.c +++ b/net/ipv4/xfrm4_policy.c @@ -104,10 +104,14 @@ _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; struct flowi4 *fl4 = &fl->u.ip4; + int oif = 0; + + if (skb_dst(skb)) + oif = skb_dst(skb)->dev->ifindex; memset(fl4, 0, sizeof(struct flowi4)); fl4->flowi4_mark = skb->mark; - fl4->flowi4_oif = skb_dst(skb)->dev->ifindex; + fl4->flowi4_oif = reverse ? skb->skb_iif : oif; if (!ip_is_fragment(iph)) { switch (iph->protocol) { diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c index dd503a3..5f8e128 100644 --- a/net/ipv6/xfrm6_policy.c +++ b/net/ipv6/xfrm6_policy.c @@ -135,10 +135,14 @@ _decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse) struct ipv6_opt_hdr *exthdr; const unsigned char *nh = skb_network_header(skb); u8 nexthdr = nh[IP6CB(skb)->nhoff]; + int oif = 0; + + if (skb_dst(skb)) + oif = skb_dst(skb)->dev->ifindex; memset(fl6, 0, sizeof(struct flowi6)); fl6->flowi6_mark = skb->mark; - fl6->flowi6_oif = skb_dst(skb)->dev->ifindex; + fl6->flowi6_oif = reverse ? skb->skb_iif : oif; fl6->daddr = reverse ? hdr->saddr : hdr->daddr; fl6->saddr = reverse ? hdr->daddr : hdr->saddr; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
