Re: [PATCH 7/8 v2] crypto: replace memset by memzero_explicit

[Ard Biesheuvel]

On 30 November 2014 at 18:03, Julia Lawall <Julia.Lawall@xxxxxxx> wrote:
> From: Julia Lawall <Julia.Lawall@xxxxxxx>
>
> Memset on a local variable may be removed when it is called just before the
> variable goes out of scope.  Using memzero_explicit defeats this
> optimization.  A simplified version of the semantic patch that makes this
> change is as follows: (http://coccinelle.lip6.fr/)
>
> // <smpl>
> @@
> identifier x;
> type T;
> @@
>
> {
> ... when any
> T x[...];
> ... when any
>     when exists
> - memset
> + memzero_explicit
>   (x,
> -0,
>   ...)
> ... when != x
>     when strict
> }
> // </smpl>
>
> This change was suggested by Daniel Borkmann <dborkman@xxxxxxxxxx>
>
> Signed-off-by: Julia Lawall <Julia.Lawall@xxxxxxx>
>
> ---
> Daniel Borkmann suggested that these patches could go through Herbert Xu's
> cryptodev tree.
>
> I was not able to compile this one.
>

Builds fine for me

Acked-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>


> v2: fixed email address
>
>  arch/arm/crypto/sha512_neon_glue.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/crypto/sha512_neon_glue.c b/arch/arm/crypto/sha512_neon_glue.c
> index f3452c6..b124dce 100644
> --- a/arch/arm/crypto/sha512_neon_glue.c
> +++ b/arch/arm/crypto/sha512_neon_glue.c
> @@ -241,7 +241,7 @@ static int sha384_neon_final(struct shash_desc *desc, u8 *hash)
>         sha512_neon_final(desc, D);
>
>         memcpy(hash, D, SHA384_DIGEST_SIZE);
> -       memset(D, 0, SHA512_DIGEST_SIZE);
> +       memzero_explicit(D, SHA512_DIGEST_SIZE);
>
>         return 0;
>  }
>
>
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