[PATCH 4.10 09/63] vxlan: dont allow overwrite of config src addr

[Greg Kroah-Hartman]

4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Brian Russell <brussell@xxxxxxxxxxx>


[ 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@xxxxxxxxxxx>
Acked-by: Jiri Benc <jbenc@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/vxlan.c |   12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1992,7 +1992,6 @@ static void vxlan_xmit_one(struct sk_buf
 	const struct iphdr *old_iph = ip_hdr(skb);
 	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;
@@ -2019,7 +2018,7 @@ static void vxlan_xmit_one(struct sk_buf
 
 		dst_port = rdst->remote_port ? rdst->remote_port : vxlan->cfg.dst_port;
 		vni = rdst->remote_vni;
-		src = &vxlan->cfg.saddr;
+		local_ip = vxlan->cfg.saddr;
 		dst_cache = &rdst->dst_cache;
 		md->gbp = skb->mark;
 		ttl = vxlan->cfg.ttl;
@@ -2052,7 +2051,6 @@ static void vxlan_xmit_one(struct sk_buf
 		dst = &remote_ip;
 		dst_port = info->key.tp_dst ? : vxlan->cfg.dst_port;
 		vni = tunnel_id_to_key32(info->key.tun_id);
-		src = &local_ip;
 		dst_cache = &info->dst_cache;
 		if (info->options_len)
 			md = ip_tunnel_info_opts(info);
@@ -2072,7 +2070,7 @@ static void vxlan_xmit_one(struct sk_buf
 		rt = vxlan_get_route(vxlan, dev, sock4, 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_port, src_port,
 				     dst_cache, info);
 		if (IS_ERR(rt)) {
@@ -2099,7 +2097,7 @@ static void vxlan_xmit_one(struct sk_buf
 		if (err < 0)
 			goto tx_error;
 
-		udp_tunnel_xmit_skb(rt, sock4->sock->sk, skb, src->sin.sin_addr.s_addr,
+		udp_tunnel_xmit_skb(rt, sock4->sock->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)
@@ -2109,7 +2107,7 @@ static void vxlan_xmit_one(struct sk_buf
 		ndst = vxlan6_get_route(vxlan, dev, sock6, skb,
 					rdst ? rdst->remote_ifindex : 0, tos,
 					label, &dst->sin6.sin6_addr,
-					&src->sin6.sin6_addr,
+					&local_ip.sin6.sin6_addr,
 					dst_port, src_port,
 					dst_cache, info);
 		if (IS_ERR(ndst)) {
@@ -2137,7 +2135,7 @@ static void vxlan_xmit_one(struct sk_buf
 			goto tx_error;
 
 		udp_tunnel6_xmit_skb(ndst, sock6->sock->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