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

[Herbert Xu <herbert@gondor.apana.org.au>]

On Thu, May 15, 2025 at 03:41:05PM +0800, kernel test robot wrote:
>
> [   16.077514][  T327] ------------[ cut here ]------------
> [   16.079451][  T327] alg: self-tests for lrw(twofish) using lrw(ecb(twofish-asm)) failed (rc=-22)

The crucial line actually got cut off:

alg: skcipher: error allocating lrw(ecb(twofish-generic)) (generic impl of lrw(twofish)): -22

The bug is in lrw, which unconditionally adds ecb() around its
parameter, so we end up with ecb(ecb(twofish-generic)), which is
then correctly rejected by the ecb template when it tries to
create the inner ecb(twofish-generic) as a simple cipher.

---8<---
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: 700cb3f5fe75 ("crypto: lrw - Convert to skcipher")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202505151503.d8a6cf10-lkp@intel.com
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/lrw.c b/crypto/lrw.c
index e7f0368f8c97..dd403b800513 100644
--- a/crypto/lrw.c
+++ b/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));
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt