2 files changed, 8 insertions, 2 deletions

diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 3c3bb184eb8f..6c4f5eac98e7 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -32,6 +32,11 @@ struct route_info {
 #define RT6_LOOKUP_F_SRCPREF_PUBLIC     0x00000010
 #define RT6_LOOKUP_F_SRCPREF_COA        0x00000020
 
+/* We do not (yet ?) support IPv6 jumbograms (RFC 2675)
+ * Unlike IPv4, hdr->seg_len doesn't include the IPv6 header
+ */
+#define IP6_MAX_MTU (0xFFFF + sizeof(struct ipv6hdr))
+
 /*
  * rt6_srcprefs2flags() and rt6_flags2srcprefs() translate
  * between IPV6_ADDR_PREFERENCES socket option values
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 5015c50a5ba7..5ea462eacd9f 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1338,7 +1338,7 @@ static unsigned int ip6_mtu(const struct dst_entry *dst)
         unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
 
         if (mtu)
-                return mtu;
+                goto out;
 
         mtu = IPV6_MIN_MTU;
 
@@ -1348,7 +1348,8 @@ static unsigned int ip6_mtu(const struct dst_entry *dst)
                 mtu = idev->cnf.mtu6;
         rcu_read_unlock();
 
-        return mtu;
+out:
+        return min_t(unsigned int, mtu, IP6_MAX_MTU);
 }
 
 static struct dst_entry *icmp6_dst_gc_list;