diff --git a/net/ndisc.c b/net/ndisc.c
index 0b27779..d1cec06 100644
--- a/net/ndisc.c
+++ b/net/ndisc.c
@@ -382,6 +382,8 @@
 	unsigned char type = 0;
 	struct icmp6_ra_prefix_info *prefix = NULL;
 
+	if (len > ETH_MAX_MTU)
+		return -EMSGSIZE;
 	/* Ignore the packet if router lifetime is 0. */
 	if (!icmp->icmp6_rt_lifetime)
 		return -EOPNOTSUPP;