geneve: avoid use-after-free of skb->data

[ Upstream commit 5b01014759991887b1e450c9def01e58c02ab81b ]

geneve{,6}_build_skb can end up doing a pskb_expand_head(), which
makes the ip_hdr(skb) reference we stashed earlier stale. Since it's
only needed as an argument to ip_tunnel_ecn_encap(), move this
directly in the function call.

Fixes: 08399efc6319 ("geneve: ensure ECN info is handled properly in all tx/rx paths")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 16af1ce99233ae725852c0f41c1a5c58eb5f0a92..5ad706b99af8c9cb27b1cfc9af3e72a2e1687014 100644 (file)
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -844,7 +844,6 @@ static netdev_tx_t geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
        struct geneve_dev *geneve = netdev_priv(dev);
        struct geneve_sock *gs4 = geneve->sock4;
        struct rtable *rt = NULL;
-       const struct iphdr *iip; /* interior IP header */
        int err = -EINVAL;
        struct flowi4 fl4;
        __u8 tos, ttl;
@@ -871,8 +870,6 @@ static netdev_tx_t geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
        sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
        skb_reset_mac_header(skb);
 
-       iip = ip_hdr(skb);
-
        if (info) {
                const struct ip_tunnel_key *key = &info->key;
                u8 *opts = NULL;
@@ -892,7 +889,7 @@ static netdev_tx_t geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
                if (unlikely(err))
                        goto tx_error;
 
-               tos = ip_tunnel_ecn_encap(key->tos, iip, skb);
+               tos = ip_tunnel_ecn_encap(key->tos, ip_hdr(skb), skb);
                ttl = key->ttl;
                df = key->tun_flags & TUNNEL_DONT_FRAGMENT ? htons(IP_DF) : 0;
        } else {
@@ -901,7 +898,7 @@ static netdev_tx_t geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
                if (unlikely(err))
                        goto tx_error;
 
-               tos = ip_tunnel_ecn_encap(fl4.flowi4_tos, iip, skb);
+               tos = ip_tunnel_ecn_encap(fl4.flowi4_tos, ip_hdr(skb), skb);
                ttl = geneve->ttl;
                if (!ttl && IN_MULTICAST(ntohl(fl4.daddr)))
                        ttl = 1;
@@ -934,7 +931,6 @@ static netdev_tx_t geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
        struct geneve_dev *geneve = netdev_priv(dev);
        struct geneve_sock *gs6 = geneve->sock6;
        struct dst_entry *dst = NULL;
-       const struct iphdr *iip; /* interior IP header */
        int err = -EINVAL;
        struct flowi6 fl6;
        __u8 prio, ttl;
@@ -959,8 +955,6 @@ static netdev_tx_t geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
        sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
        skb_reset_mac_header(skb);
 
-       iip = ip_hdr(skb);
-
        if (info) {
                const struct ip_tunnel_key *key = &info->key;
                u8 *opts = NULL;
@@ -981,7 +975,7 @@ static netdev_tx_t geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
                if (unlikely(err))
                        goto tx_error;
 
-               prio = ip_tunnel_ecn_encap(key->tos, iip, skb);
+               prio = ip_tunnel_ecn_encap(key->tos, ip_hdr(skb), skb);
                ttl = key->ttl;
                label = info->key.label;
        } else {
@@ -991,7 +985,7 @@ static netdev_tx_t geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
                        goto tx_error;
 
                prio = ip_tunnel_ecn_encap(ip6_tclass(fl6.flowlabel),
-                                          iip, skb);
+                                          ip_hdr(skb), skb);
                ttl = geneve->ttl;
                if (!ttl && ipv6_addr_is_multicast(&fl6.daddr))
                        ttl = 1;