diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index cd6ce6a..37221f6 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -229,6 +229,8 @@
 
 	arg.iph = iph;
 	arg.user = user;
+
+	read_lock(&ip4_frags.lock);
 	hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol);
 
 	q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash);