1 files changed, 15 insertions, 10 deletions

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index fc6d7d143f2c..844642682b83 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1682,16 +1682,16 @@ static int grec_size(struct ifmcaddr6 *pmc, int type, int gdel, int sdel)
 }
 
 static struct sk_buff *add_grhead(struct sk_buff *skb, struct ifmcaddr6 *pmc,
-        int type, struct mld2_grec **ppgr)
+        int type, struct mld2_grec **ppgr, unsigned int mtu)
 {
-        struct net_device *dev = pmc->idev->dev;
         struct mld2_report *pmr;
         struct mld2_grec *pgr;
 
-        if (!skb)
-                skb = mld_newpack(pmc->idev, dev->mtu);
-        if (!skb)
-                return NULL;
+        if (!skb) {
+                skb = mld_newpack(pmc->idev, mtu);
+                if (!skb)
+                        return NULL;
+        }
         pgr = skb_put(skb, sizeof(struct mld2_grec));
         pgr->grec_type = type;
         pgr->grec_auxwords = 0;
@@ -1714,10 +1714,15 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc,
         struct mld2_grec *pgr = NULL;
         struct ip6_sf_list *psf, *psf_next, *psf_prev, **psf_list;
         int scount, stotal, first, isquery, truncate;
+        unsigned int mtu;
 
         if (pmc->mca_flags & MAF_NOREPORT)
                 return skb;
 
+        mtu = READ_ONCE(dev->mtu);
+        if (mtu < IPV6_MIN_MTU)
+                return skb;
+
         isquery = type == MLD2_MODE_IS_INCLUDE ||
                   type == MLD2_MODE_IS_EXCLUDE;
         truncate = type == MLD2_MODE_IS_EXCLUDE ||
@@ -1738,7 +1743,7 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc,
                     AVAILABLE(skb) < grec_size(pmc, type, gdeleted, sdeleted)) {
                         if (skb)
                                 mld_sendpack(skb);
-                        skb = mld_newpack(idev, dev->mtu);
+                        skb = mld_newpack(idev, mtu);
                 }
         }
         first = 1;
@@ -1774,12 +1779,12 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc,
                                 pgr->grec_nsrcs = htons(scount);
                         if (skb)
                                 mld_sendpack(skb);
-                        skb = mld_newpack(idev, dev->mtu);
+                        skb = mld_newpack(idev, mtu);
                         first = 1;
                         scount = 0;
                 }
                 if (first) {
-                        skb = add_grhead(skb, pmc, type, &pgr);
+                        skb = add_grhead(skb, pmc, type, &pgr, mtu);
                         first = 0;
                 }
                 if (!skb)
@@ -1814,7 +1819,7 @@ empty_source:
                                 mld_sendpack(skb);
                                 skb = NULL; /* add_grhead will get a new one */
                         }
-                        skb = add_grhead(skb, pmc, type, &pgr);
+                        skb = add_grhead(skb, pmc, type, &pgr, mtu);
                 }
         }
         if (pgr)