On Sun, Sep 07, 2014 at 11:23:38PM +0200, Daniel Borkmann wrote:
> Recently, in commit 13aa93c70e71 ("random: add and use memzero_explicit()
> for clearing data"), we have found that GCC may optimize some memset()
> cases away when it detects a stack variable is not being used anymore
> and going out of scope. This can happen, for example, in cases when we
> are clearing out sensitive information such as keying material or any
> e.g. intermediate results from crypto computations, etc.
>
> With the help of Coccinelle, we can figure out and fix such occurences
> in the crypto subsytem as well. Julia Lawall provided the following
> Coccinelle program:
>
> @@
> type T;
> identifier x;
> @@
>
> T x;
> ... when exists
> when any
> -memset
> +memzero_explicit
> (&x,
> -0,
> ...)
> ... when != x
> when strict
>
> @@
> type T;
> identifier x;
> @@
>
> T x[...];
> ... when exists
> when any
> -memset
> +memzero_explicit
> (x,
> -0,
> ...)
> ... when != x
> when strict
>
> Therefore, make use of the drop-in replacement memzero_explicit() for
> exactly such cases instead of using memset().
>
> Signed-off-by: Daniel Borkmann <dborkman@xxxxxxxxxx>
> Cc: Julia Lawall <julia.lawall@xxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Cc: Theodore Ts'o <tytso@xxxxxxx>
> Cc: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Acked-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Thanks,
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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