net: don't call update_pmtu unconditionally

commit f15ca723c1ebe6c1a06bc95fda6b62cd87b44559 upstream.

Some dst_ops (e.g. md_dst_ops)) doesn't set this handler. It may result to:
"BUG: unable to handle kernel NULL pointer dereference at           (null)"

Let's add a helper to check if update_pmtu is available before calling it.

Fixes: 52a589d51f10 ("geneve: update skb dst pmtu on tx path")
Fixes: a93bf0ff4490 ("vxlan: update skb dst pmtu on tx path")
CC: Roman Kapl <code@rkapl.cz>
CC: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Thomas Deutschmann <whissi@gentoo.org>
Cc: Eddie Chapman <eddie@ehuk.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
index 7774654..7a5ed5a 100644 (file)
--- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
@@ -1447,8 +1447,7 @@ void ipoib_cm_skb_too_long(struct net_device *dev, struct sk_buff *skb,
        struct ipoib_dev_priv *priv = ipoib_priv(dev);
        int e = skb_queue_empty(&priv->cm.skb_queue);
 
-       if (skb_dst(skb))
-               skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
+       skb_dst_update_pmtu(skb, mtu);
 
        skb_queue_tail(&priv->cm.skb_queue, skb);
        if (e)

diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 1b0fcf0..fbc825a 100644 (file)
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -829,7 +829,7 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
                int mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr) -
                          GENEVE_BASE_HLEN - info->options_len - 14;
 
-               skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
+               skb_dst_update_pmtu(skb, mtu);
        }
 
        sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
@@ -875,7 +875,7 @@ static int geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
                int mtu = dst_mtu(dst) - sizeof(struct ipv6hdr) -
                          GENEVE_BASE_HLEN - info->options_len - 14;
 
-               skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
+               skb_dst_update_pmtu(skb, mtu);
        }
 
        sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index bb44f0c..3d9c5b3 100644 (file)
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2158,8 +2158,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                if (skb_dst(skb)) {
                        int mtu = dst_mtu(ndst) - VXLAN_HEADROOM;
 
-                       skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL,
-                                                      skb, mtu);
+                       skb_dst_update_pmtu(skb, mtu);
                }
 
                tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
@@ -2200,8 +2199,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                if (skb_dst(skb)) {
                        int mtu = dst_mtu(ndst) - VXLAN6_HEADROOM;
 
-                       skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL,
-                                                      skb, mtu);
+                       skb_dst_update_pmtu(skb, mtu);
                }
 
                tos = ip_tunnel_ecn_encap(tos, old_iph, skb);

diff --git a/include/net/dst.h b/include/net/dst.h
index 694c2e6..ebfb432 100644 (file)
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -520,4 +520,12 @@ static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
 }
 #endif
 
+static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu)
+{
+       struct dst_entry *dst = skb_dst(skb);
+
+       if (dst && dst->ops->update_pmtu)
+               dst->ops->update_pmtu(dst, NULL, skb, mtu);
+}
+
 #endif /* _NET_DST_H */

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 13f7bbc..a2fcc20 100644 (file)
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -521,8 +521,7 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
        else
                mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
 
-       if (skb_dst(skb))
-               skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
+       skb_dst_update_pmtu(skb, mtu);
 
        if (skb->protocol == htons(ETH_P_IP)) {
                if (!skb_is_gso(skb) &&

diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index 89453cf..c9cd891 100644 (file)
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -209,7 +209,7 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev,
 
        mtu = dst_mtu(dst);
        if (skb->len > mtu) {
-               skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
+               skb_dst_update_pmtu(skb, mtu);
                if (skb->protocol == htons(ETH_P_IP)) {
                        icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
                                  htonl(mtu));

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 7e11f6a..d61a82f 100644 (file)
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -652,7 +652,7 @@ ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                if (rel_info > dst_mtu(skb_dst(skb2)))
                        goto out;
 
-               skb_dst(skb2)->ops->update_pmtu(skb_dst(skb2), NULL, skb2, rel_info);
+               skb_dst_update_pmtu(skb2, rel_info);
        }
        if (rel_type == ICMP_REDIRECT)
                skb_dst(skb2)->ops->redirect(skb_dst(skb2), NULL, skb2);
@@ -1141,8 +1141,7 @@ route_lookup:
                mtu = 576;
        }
 
-       if (skb_dst(skb) && !t->parms.collect_md)
-               skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
+       skb_dst_update_pmtu(skb, mtu);
        if (skb->len - t->tun_hlen - eth_hlen > mtu && !skb_is_gso(skb)) {
                *pmtu = mtu;
                err = -EMSGSIZE;

diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index 7c0f647..2493a40 100644 (file)
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -486,7 +486,7 @@ vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
 
        mtu = dst_mtu(dst);
        if (!skb->ignore_df && skb->len > mtu) {
-               skb_dst(skb)->ops->update_pmtu(dst, NULL, skb, mtu);
+               skb_dst_update_pmtu(skb, mtu);
 
                if (skb->protocol == htons(ETH_P_IPV6)) {
                        if (mtu < IPV6_MIN_MTU)

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index f03c1a5..b35d890 100644 (file)
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -925,8 +925,8 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                        df = 0;
                }
 
-               if (tunnel->parms.iph.daddr && skb_dst(skb))
-                       skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
+               if (tunnel->parms.iph.daddr)
+                       skb_dst_update_pmtu(skb, mtu);
 
                if (skb->len > mtu && !skb_is_gso(skb)) {
                        icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);