1 files changed, 5 insertions, 4 deletions

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 9648de2b6745..ed2c4e400b46 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1550,7 +1550,7 @@ static void ip6_mc_hdr(struct sock *sk, struct sk_buff *skb,
         hdr->daddr = *daddr;
 }
 
-static struct sk_buff *mld_newpack(struct inet6_dev *idev, int size)
+static struct sk_buff *mld_newpack(struct inet6_dev *idev, unsigned int mtu)
 {
         struct net_device *dev = idev->dev;
         struct net *net = dev_net(dev);
@@ -1561,13 +1561,13 @@ static struct sk_buff *mld_newpack(struct inet6_dev *idev, int size)
         const struct in6_addr *saddr;
         int hlen = LL_RESERVED_SPACE(dev);
         int tlen = dev->needed_tailroom;
+        unsigned int size = mtu + hlen + tlen;
         int err;
         u8 ra[8] = { IPPROTO_ICMPV6, 0,
                      IPV6_TLV_ROUTERALERT, 2, 0, 0,
                      IPV6_TLV_PADN, 0 };
 
         /* we assume size > sizeof(ra) here */
-        size += hlen + tlen;
         /* limit our allocations to order-0 page */
         size = min_t(int, size, SKB_MAX_ORDER(0, 0));
         skb = sock_alloc_send_skb(sk, size, 1, &err);
@@ -1576,6 +1576,8 @@ static struct sk_buff *mld_newpack(struct inet6_dev *idev, int size)
                 return NULL;
 
         skb->priority = TC_PRIO_CONTROL;
+        skb->reserved_tailroom = skb_end_offset(skb) -
+                                 min(mtu, skb_end_offset(skb));
         skb_reserve(skb, hlen);
 
         if (__ipv6_get_lladdr(idev, &addr_buf, IFA_F_TENTATIVE)) {
@@ -1690,8 +1692,7 @@ static struct sk_buff *add_grhead(struct sk_buff *skb, struct ifmcaddr6 *pmc,
         return skb;
 }
 
-#define AVAILABLE(skb) ((skb) ? ((skb)->dev ? (skb)->dev->mtu - (skb)->len : \
-        skb_tailroom(skb)) : 0)
+#define AVAILABLE(skb)  ((skb) ? skb_availroom(skb) : 0)
 
 static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc,
         int type, int gdeleted, int sdeleted, int crsend)