From a64407fafe09ca33b09aabd49c5d526b1b6b7528 Mon Sep 17 00:00:00 2001
From: Brian Russell <brussell@brocade.com>
Date: Fri, 24 Feb 2017 17:47:11 +0000
Subject: vxlan: don't allow overwrite of config src addr

[ Upstream commit 1158632b5a2dcce0786c1b1b99654e81cc867981 ]

When using IPv6 transport and a default dst, a pointer to the configured
source address is passed into the route lookup. If no source address is
configured, then the value is overwritten.

IPv6 route lookup ignores egress ifindex match if the source address is set,
so if egress ifindex match is desired, the source address must be passed
as any. The overwrite breaks this for subsequent lookups.

Avoid this by copying the configured address to an existing stack variable
and pass a pointer to that instead.

Fixes: 272d96a5ab10 ("net: vxlan: lwt: Use source ip address during route lookup.")

Signed-off-by: Brian Russell <brussell@brocade.com>
Acked-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 7e3b2e2..ac3f8d5 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1942,7 +1942,6 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 	const struct iphdr *old_iph;
 	union vxlan_addr *dst;
 	union vxlan_addr remote_ip, local_ip;
-	union vxlan_addr *src;
 	struct vxlan_metadata _md;
 	struct vxlan_metadata *md = &_md;
 	__be16 src_port = 0, dst_port;
@@ -1960,7 +1959,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 		dst_port = rdst->remote_port ? rdst->remote_port : vxlan->cfg.dst_port;
 		vni = rdst->remote_vni;
 		dst = &rdst->remote_ip;
-		src = &vxlan->cfg.saddr;
+		local_ip = vxlan->cfg.saddr;
 		dst_cache = &rdst->dst_cache;
 	} else {
 		if (!info) {
@@ -1979,7 +1978,6 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 			local_ip.sin6.sin6_addr = info->key.u.ipv6.src;
 		}
 		dst = &remote_ip;
-		src = &local_ip;
 		dst_cache = &info->dst_cache;
 	}
 
@@ -2028,7 +2026,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 		rt = vxlan_get_route(vxlan, skb,
 				     rdst ? rdst->remote_ifindex : 0, tos,
 				     dst->sin.sin_addr.s_addr,
-				     &src->sin.sin_addr.s_addr,
+				     &local_ip.sin.sin_addr.s_addr,
 				     dst_cache, info);
 		if (IS_ERR(rt)) {
 			netdev_dbg(dev, "no route to %pI4\n",
@@ -2071,7 +2069,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 		if (err < 0)
 			goto xmit_tx_error;
 
-		udp_tunnel_xmit_skb(rt, sk, skb, src->sin.sin_addr.s_addr,
+		udp_tunnel_xmit_skb(rt, sk, skb, local_ip.sin.sin_addr.s_addr,
 				    dst->sin.sin_addr.s_addr, tos, ttl, df,
 				    src_port, dst_port, xnet, !udp_sum);
 #if IS_ENABLED(CONFIG_IPV6)
@@ -2087,7 +2085,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 		ndst = vxlan6_get_route(vxlan, skb,
 					rdst ? rdst->remote_ifindex : 0, tos,
 					label, &dst->sin6.sin6_addr,
-					&src->sin6.sin6_addr,
+					&local_ip.sin6.sin6_addr,
 					dst_cache, info);
 		if (IS_ERR(ndst)) {
 			netdev_dbg(dev, "no route to %pI6\n",
@@ -2134,7 +2132,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 			return;
 		}
 		udp_tunnel6_xmit_skb(ndst, sk, skb, dev,
-				     &src->sin6.sin6_addr,
+				     &local_ip.sin6.sin6_addr,
 				     &dst->sin6.sin6_addr, tos, ttl,
 				     label, src_port, dst_port, !udp_sum);
 #endif
-- 
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