crypto: lrw - Only add ecb if it is not already there

Only add ecb to the cipher name if it isn't already ecb.

Also use memcmp instead of strncmp since these strings are all
stored in an array of length CRYPTO_MAX_ALG_NAME.

Fixes: 700cb3f ("crypto: lrw - Convert to skcipher")
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-lkp/[email protected]
Signed-off-by: Herbert Xu <[email protected]>

Author: herbertx

crypto/lrw.c

@@ -322,7 +322,7 @@ static int lrw_create(struct crypto_template *tmpl, struct rtattr **tb)
 
 	err = crypto_grab_skcipher(spawn, skcipher_crypto_instance(inst),
 				   cipher_name, 0, mask);
-	if (err == -ENOENT) {
+	if (err == -ENOENT && memcmp(cipher_name, "ecb(", 4)) {
 		err = -ENAMETOOLONG;
 		if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
 			     cipher_name) >= CRYPTO_MAX_ALG_NAME)
@@ -356,7 +356,7 @@ static int lrw_create(struct crypto_template *tmpl, struct rtattr **tb)
 	/* Alas we screwed up the naming so we have to mangle the
 	 * cipher name.
 	 */
-	if (!strncmp(cipher_name, "ecb(", 4)) {
+	if (!memcmp(cipher_name, "ecb(", 4)) {
 		int len;
 
 		len = strscpy(ecb_name, cipher_name + 4, sizeof(ecb_name));