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)