linux-kernel - [PATCH] crypto: LLVMLinux: Remove VLAIS from crypto/n2

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Date:	Fri,  5 Sep 2014 16:00:08 -0700
From:	behanw@...verseincode.com
To:	davem@...emloft.net, herbert@...dor.apana.org.au
Cc:	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
	Behan Webster <behanw@...verseincode.com>,
	Mark Charlebois <charlebm@...il.com>,
	Jan-Simon Möller <dl9pf@....de>
Subject: [PATCH] crypto: LLVMLinux: Remove VLAIS from crypto/n2_core.c

From: Behan Webster <behanw@...verseincode.com>

Replaced the use of a Variable Length Array In Struct (VLAIS) with a C99
compliant equivalent. This patch allocates the appropriate amount of memory
using an char array.

The new code can be compiled with both gcc and clang.

struct shash_desc contains a flexible array member member ctx declared with
CRYPTO_MINALIGN_ATTR, so sizeof(struct shash_desc) aligns the beginning
of the array declared after struct shash_desc with long long.

No trailing padding is required because it is not a struct type that can
be used in an array.

The CRYPTO_MINALIGN_ATTR is required so that desc is aligned with long long
as would be the case for a struct containing a member with
CRYPTO_MINALIGN_ATTR.

Signed-off-by: Behan Webster <behanw@...verseincode.com>
Signed-off-by: Mark Charlebois <charlebm@...il.com>
Signed-off-by: Jan-Simon Möller <dl9pf@....de>
---
 drivers/crypto/n2_core.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/crypto/n2_core.c b/drivers/crypto/n2_core.c
index 7263c10..ed142d1 100644
--- a/drivers/crypto/n2_core.c
+++ b/drivers/crypto/n2_core.c
@@ -445,10 +445,9 @@ static int n2_hmac_async_setkey(struct crypto_ahash *tfm, const u8 *key,
 	struct n2_hmac_ctx *ctx = crypto_ahash_ctx(tfm);
 	struct crypto_shash *child_shash = ctx->child_shash;
 	struct crypto_ahash *fallback_tfm;
-	struct {
-		struct shash_desc shash;
-		char ctx[crypto_shash_descsize(child_shash)];
-	} desc;
+	char desc[sizeof(struct shash_desc) +
+		crypto_shash_descsize(child_shash)] CRYPTO_MINALIGN_ATTR;
+	struct shash_desc *shash = (struct shash_desc *)desc;
 	int err, bs, ds;
 
 	fallback_tfm = ctx->base.fallback_tfm;
@@ -456,15 +455,15 @@ static int n2_hmac_async_setkey(struct crypto_ahash *tfm, const u8 *key,
 	if (err)
 		return err;
 
-	desc.shash.tfm = child_shash;
-	desc.shash.flags = crypto_ahash_get_flags(tfm) &
+	shash->tfm = child_shash;
+	shash->flags = crypto_ahash_get_flags(tfm) &
 		CRYPTO_TFM_REQ_MAY_SLEEP;
 
 	bs = crypto_shash_blocksize(child_shash);
 	ds = crypto_shash_digestsize(child_shash);
 	BUG_ON(ds > N2_HASH_KEY_MAX);
 	if (keylen > bs) {
-		err = crypto_shash_digest(&desc.shash, key, keylen,
+		err = crypto_shash_digest(shash, key, keylen,
 					  ctx->hash_key);
 		if (err)
 			return err;
-- 
1.9.1

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