NFSD: Full checking of authentication name

Signed-off-by: Kinglong Mee <[e-mail]>
Signed-off-by: J. Bruce Fields <[e-mail]>

fs/nfsd/nfs4idmap.c

···
 	memset(&ent, 0, sizeof(ent));
 
 	/* Authentication name */
-	if (qword_get(&buf, buf1, PAGE_SIZE) <= 0)
+	len = qword_get(&buf, buf1, PAGE_SIZE);
+	if (len <= 0 || len >= IDMAP_NAMESZ)
 		goto out;
 	memcpy(ent.authname, buf1, sizeof(ent.authname));
 
···
 	/* Name */
 	error = -EINVAL;
 	len = qword_get(&buf, buf1, PAGE_SIZE);
-	if (len < 0)
+	if (len < 0 || len >= IDMAP_NAMESZ)
 		goto out;
 	if (len == 0)
 		set_bit(CACHE_NEGATIVE, &ent.h.flags);
-	else if (len >= IDMAP_NAMESZ)
-		goto out;
 	else
 		memcpy(ent.name, buf1, sizeof(ent.name));
 	error = -ENOMEM;
···
 		goto out;
 
 	cache_put(&res->h, cd);
-
 	error = 0;
 out:
 	kfree(buf1);
-
 	return error;
 }
-
 
 static struct ent *
 idtoname_lookup(struct cache_detail *cd, struct ent *item)
···
 	memset(&ent, 0, sizeof(ent));
 
 	/* Authentication name */
-	if (qword_get(&buf, buf1, PAGE_SIZE) <= 0)
+	len = qword_get(&buf, buf1, PAGE_SIZE);
+	if (len <= 0 || len >= IDMAP_NAMESZ)
 		goto out;
 	memcpy(ent.authname, buf1, sizeof(ent.authname));
 
···
 	error = 0;
 out:
 	kfree(buf1);
-
 	return (error);
 }