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authorWANG Cong <xiyou.wangcong@gmail.com>2017-04-25 14:37:15 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-05-03 08:36:37 -0700
commitdf1926123f0c390d4ccbea5760ac0428b6f7cae4 (patch)
tree0b97ae8d2641003b9d60d234fc83b1925a2684bf /net
parentae6a762dcdf0a72baa448dbd8d5d77ad89ca1962 (diff)
ipv6: check skb->protocol before lookup for nexthop
[ Upstream commit 199ab00f3cdb6f154ea93fa76fd80192861a821d ] Andrey reported a out-of-bound access in ip6_tnl_xmit(), this is because we use an ipv4 dst in ip6_tnl_xmit() and cast an IPv4 neigh key as an IPv6 address: neigh = dst_neigh_lookup(skb_dst(skb), &ipv6_hdr(skb)->daddr); if (!neigh) goto tx_err_link_failure; addr6 = (struct in6_addr *)&neigh->primary_key; // <=== HERE addr_type = ipv6_addr_type(addr6); if (addr_type == IPV6_ADDR_ANY) addr6 = &ipv6_hdr(skb)->daddr; memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr)); Also the network header of the skb at this point should be still IPv4 for 4in6 tunnels, we shold not just use it as IPv6 header. This patch fixes it by checking if skb->protocol is ETH_P_IPV6: if it is, we are safe to do the nexthop lookup using skb_dst() and ipv6_hdr(skb)->daddr; if not (aka IPv4), we have no clue about which dest address we can pick here, we have to rely on callers to fill it from tunnel config, so just fall to ip6_route_output() to make the decision. Fixes: ea3dc9601bda ("ip6_tunnel: Add support for wildcard tunnel endpoints.") Reported-by: Andrey Konovalov <andreyknvl@google.com> Tested-by: Andrey Konovalov <andreyknvl@google.com> Cc: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-rw-r--r--net/ipv6/ip6_tunnel.c34
1 files changed, 18 insertions, 16 deletions
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index f6ba45242851..116b4da06820 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1037,7 +1037,7 @@ int ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev, __u8 dsfield,
struct ip6_tnl *t = netdev_priv(dev);
struct net *net = t->net;
struct net_device_stats *stats = &t->dev->stats;
- struct ipv6hdr *ipv6h = ipv6_hdr(skb);
+ struct ipv6hdr *ipv6h;
struct ipv6_tel_txoption opt;
struct dst_entry *dst = NULL, *ndst = NULL;
struct net_device *tdev;
@@ -1057,26 +1057,28 @@ int ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev, __u8 dsfield,
/* NBMA tunnel */
if (ipv6_addr_any(&t->parms.raddr)) {
- struct in6_addr *addr6;
- struct neighbour *neigh;
- int addr_type;
+ if (skb->protocol == htons(ETH_P_IPV6)) {
+ struct in6_addr *addr6;
+ struct neighbour *neigh;
+ int addr_type;
- if (!skb_dst(skb))
- goto tx_err_link_failure;
+ if (!skb_dst(skb))
+ goto tx_err_link_failure;
- neigh = dst_neigh_lookup(skb_dst(skb),
- &ipv6_hdr(skb)->daddr);
- if (!neigh)
- goto tx_err_link_failure;
+ neigh = dst_neigh_lookup(skb_dst(skb),
+ &ipv6_hdr(skb)->daddr);
+ if (!neigh)
+ goto tx_err_link_failure;
- addr6 = (struct in6_addr *)&neigh->primary_key;
- addr_type = ipv6_addr_type(addr6);
+ addr6 = (struct in6_addr *)&neigh->primary_key;
+ addr_type = ipv6_addr_type(addr6);
- if (addr_type == IPV6_ADDR_ANY)
- addr6 = &ipv6_hdr(skb)->daddr;
+ if (addr_type == IPV6_ADDR_ANY)
+ addr6 = &ipv6_hdr(skb)->daddr;
- memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr));
- neigh_release(neigh);
+ memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr));
+ neigh_release(neigh);
+ }
} else if (!(t->parms.flags &
(IP6_TNL_F_USE_ORIG_TCLASS | IP6_TNL_F_USE_ORIG_FWMARK))) {
/* enable the cache only only if the routing decision does