diff --git a/kernel/uid16.c b/kernel/uid16.c
index 51c6e89..e530bc3 100644
--- a/kernel/uid16.c
+++ b/kernel/uid16.c
@@ -134,11 +134,14 @@
 static int groups16_to_user(old_gid_t __user *grouplist,
     struct group_info *group_info)
 {
+	struct user_namespace *user_ns = current_user_ns();
 	int i;
 	old_gid_t group;
+	kgid_t kgid;
 
 	for (i = 0; i < group_info->ngroups; i++) {
-		group = high2lowgid(GROUP_AT(group_info, i));
+		kgid = GROUP_AT(group_info, i);
+		group = high2lowgid(from_kgid_munged(user_ns, kgid));
 		if (put_user(group, grouplist+i))
 			return -EFAULT;
 	}
@@ -149,13 +152,20 @@
 static int groups16_from_user(struct group_info *group_info,
     old_gid_t __user *grouplist)
 {
+	struct user_namespace *user_ns = current_user_ns();
 	int i;
 	old_gid_t group;
+	kgid_t kgid;
 
 	for (i = 0; i < group_info->ngroups; i++) {
 		if (get_user(group, grouplist+i))
 			return  -EFAULT;
-		GROUP_AT(group_info, i) = low2highgid(group);
+
+		kgid = make_kgid(user_ns, low2highgid(group));
+		if (!gid_valid(kgid))
+			return -EINVAL;
+
+		GROUP_AT(group_info, i) = kgid;
 	}
 
 	return 0;