svn commit: r262318 - stable/10/sys/geom/eli

[Brooks Davis]

On Sat, Feb 22, 2014 at 12:30:33AM +0000, Xin LI wrote:
> Author: delphij
> Date: Sat Feb 22 00:30:33 2014
> New Revision: 262318
> URL: http://svnweb.freebsd.org/changeset/base/262318
> 
> Log:
>   MFC r261618:
>   
>   In g_eli_crypto_hmac_init(), zero out after using the ipad buffer,
>   k_ipad.
>   
>   Note that the two consumers in geli(4) are not affected by this
>   issue because the way the code is constructed and as such, we
>   believe there is no security impact with or without this change
>   with geli(4)'s usage.
>   
>   Reported by:	Serge van den Boom <serge vdboom.org>
>   Reviewed by:	pjd
> 
> Modified:
>   stable/10/sys/geom/eli/g_eli_crypto.c
> Directory Properties:
>   stable/10/   (props changed)
> 
> Modified: stable/10/sys/geom/eli/g_eli_crypto.c
> ==============================================================================
> --- stable/10/sys/geom/eli/g_eli_crypto.c	Sat Feb 22 00:16:27 2014	(r262317)
> +++ stable/10/sys/geom/eli/g_eli_crypto.c	Sat Feb 22 00:30:33 2014	(r262318)
> @@ -265,6 +265,7 @@ g_eli_crypto_hmac_init(struct hmac_ctx *
>  	/* Perform inner SHA512. */
>  	SHA512_Init(&ctx->shactx);
>  	SHA512_Update(&ctx->shactx, k_ipad, sizeof(k_ipad));
> +	bzero(k_ipad, sizeof(k_ipad));
>  }
>  
>  void
> 

Unless k_ipad is declared volatile there is some risk an overly smart
compiler will optimize this bzero() away.  It might make sense for us to
use a non-standard function for such zeroing operations.

-- Brooks
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