2014-09-05 23:03:34

by Behan Webster

Subject: [PATCH] bluetooth: LLVMLinux: Remove VLAIS from bluetooth/amp.c

From: Behan Webster <[email protected]>

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 <[email protected]>
Signed-off-by: Mark Charlebois <[email protected]>
Signed-off-by: Jan-Simon Möller <[email protected]>
---
net/bluetooth/amp.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/net/bluetooth/amp.c b/net/bluetooth/amp.c
index 016cdb6..2640d78 100644
--- a/net/bluetooth/amp.c
+++ b/net/bluetooth/amp.c
@@ -149,15 +149,14 @@ static int hmac_sha256(u8 *key, u8 ksize, char *plaintext, u8 psize, u8 *output)
if (ret) {
BT_DBG("crypto_ahash_setkey failed: err %d", ret);
} else {
- struct {
- struct shash_desc shash;
- char ctx[crypto_shash_descsize(tfm)];
- } desc;
+ char desc[sizeof(struct shash_desc) +
+ crypto_shash_descsize(tfm)] CRYPTO_MINALIGN_ATTR;
+ struct shash_desc *shash = (struct shash_desc *)desc;

- desc.shash.tfm = tfm;
- desc.shash.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+ shash->tfm = tfm;
+ shash->flags = CRYPTO_TFM_REQ_MAY_SLEEP;

- ret = crypto_shash_digest(&desc.shash, plaintext, psize,
+ ret = crypto_shash_digest(shash, plaintext, psize,
output);
}

--
1.9.1

2014-09-05 23:22:16

by Marcel Holtmann

Subject: Re: [PATCH] bluetooth: LLVMLinux: Remove VLAIS from bluetooth/amp.c

Hi Behan,

> 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 <[email protected]>
> Signed-off-by: Mark Charlebois <[email protected]>
> Signed-off-by: Jan-Simon M?ller <[email protected]>
> ---
> net/bluetooth/amp.c | 13 ++++++-------
> 1 file changed, 6 insertions(+), 7 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel