crypto: hmac - fix memory leak in hmac_init_tfm()

When I added the sanity check of 'descsize', I missed that the child
hash tfm needs to be freed if the sanity check fails.  Of course this
should never happen, hence the use of WARN_ON(), but it should be fixed.

Fixes: e1354400b2 ("crypto: hash - fix incorrect HASH_MAX_DESCSIZE")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/hmac.c

@@ -157,8 +157,10 @@ static int hmac_init_tfm(struct crypto_tfm *tfm)
 
 	parent->descsize = sizeof(struct shash_desc) +
 			   crypto_shash_descsize(hash);
-	if (WARN_ON(parent->descsize > HASH_MAX_DESCSIZE))
+	if (WARN_ON(parent->descsize > HASH_MAX_DESCSIZE)) {
+		crypto_free_shash(hash);
 		return -EINVAL;
+	}
 
 	ctx->hash = hash;
 	return 0;