Re: [PATCH] crypto: use memzero_explicit instead of memset to clear contexts.

From: Herbert Xu
Date: Thu Nov 29 2018 - 01:49:21 EST


On Wed, Nov 28, 2018 at 07:36:50PM +0000, David CARLIER wrote:
> There might be a little performance drop but to make sure it stands
> by it comments, we really wipe the whole context after usage.
> ---
> crypto/chacha20poly1305.c | 3 ++-
> crypto/md5.c | 2 +-
> crypto/rmd128.c | 3 ++-
> crypto/rmd160.c | 3 ++-
> crypto/rmd256.c | 3 ++-
> crypto/rmd320.c | 3 ++-
> crypto/sha3_generic.c | 3 ++-
> 7 files changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/crypto/chacha20poly1305.c b/crypto/chacha20poly1305.c
> index 600afa99941f..6e93d998109e 100644
> --- a/crypto/chacha20poly1305.c
> +++ b/crypto/chacha20poly1305.c
> @@ -19,6 +19,7 @@
> #include <linux/init.h>
> #include <linux/kernel.h>
> #include <linux/module.h>
> +#include <linux/string.h>
>
> #include "internal.h"
>
> @@ -388,7 +389,7 @@ static int poly_genkey(struct aead_request *req)
> }
>
> sg_init_table(creq->src, 1);
> - memset(rctx->key, 0, sizeof(rctx->key));
> + memzero_explicit(rctx->key, sizeof(rctx->key));

Please explain the purpose of this patch. As it stands this
makes no sense.

Thanks,
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
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