crypto: qat - Remove VLA usage

In the quest to remove all stack VLA usage from the kernel[1], this uses
the new upper bound for the stack buffer. Also adds a sanity check.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.comSigned-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/qat/qat_common/qat_algs.c

@@ -153,8 +153,8 @@ static int qat_alg_do_precomputes(struct icp_qat_hw_auth_algo_blk *hash,
 	struct sha512_state sha512;
 	int block_size = crypto_shash_blocksize(ctx->hash_tfm);
 	int digest_size = crypto_shash_digestsize(ctx->hash_tfm);
-	char ipad[block_size];
-	char opad[block_size];
+	char ipad[MAX_ALGAPI_BLOCKSIZE];
+	char opad[MAX_ALGAPI_BLOCKSIZE];
 	__be32 *hash_state_out;
 	__be64 *hash512_state_out;
 	int i, offset;
@@ -164,6 +164,10 @@ static int qat_alg_do_precomputes(struct icp_qat_hw_auth_algo_blk *hash,
 	shash->tfm = ctx->hash_tfm;
 	shash->flags = 0x0;
 
+	if (WARN_ON(block_size > sizeof(ipad) ||
+		    sizeof(ipad) != sizeof(opad)))
+		return -EINVAL;
+
 	if (auth_keylen > block_size) {
 		int ret = crypto_shash_digest(shash, auth_key,
 					      auth_keylen, ipad);