linux-hardening - Re: [PATCH] crypto/caam: Avoid GCC constprop bug warning

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Message-ID: <Y2TVXDfQUwlYFv9S@gondor.apana.org.au>
Date:   Fri, 4 Nov 2022 17:03:24 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Kees Cook <keescook@...omium.org>
Cc:     Horia Geantă <horia.geanta@....com>,
        Pankaj Gupta <pankaj.gupta@....com>,
        Gaurav Jain <gaurav.jain@....com>,
        "David S. Miller" <davem@...emloft.net>,
        linux-crypto@...r.kernel.org, kernel test robot <lkp@...el.com>,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] crypto/caam: Avoid GCC constprop bug warning

On Fri, Oct 28, 2022 at 02:05:31PM -0700, Kees Cook wrote:
>
> @@ -163,7 +163,7 @@ static inline void append_data(u32 * const desc, const void *data, int len)
>  {
>  	u32 *offset = desc_end(desc);
>  
> -	if (len) /* avoid sparse warning: memcpy with byte count of 0 */
> +	if (data && len) /* avoid sparse warning: memcpy with byte count of 0 */
>  		memcpy(offset, data, len);

How about just killing the if clause altogether? I don't see
any sparse warnings without it.  What am I missing?

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt