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SubjectRe: [PATCH] crypto: caam - Avoid GCC memset bug warning
On Wed, Dec 28, 2022 at 04:46:39PM +0800, Herbert Xu wrote:
> Certain versions of gcc don't like the memcpy with a NULL dst
> (which only happens with a zero length). This only happens
> when debugging is enabled so add an if clause to work around
> these warnings.
>
> A similar warning used to be generated by sparse but that was
> fixed years ago.
>
> Link: https://lore.kernel.org/lkml/202210290446.qBayTfzl-lkp@intel.com
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Kees Cook <keescook@chromium.org>
> Reported-by: Uwe Kleine-K�nig <u.kleine-koenig@pengutronix.de>
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
>
> diff --git a/drivers/crypto/caam/desc_constr.h b/drivers/crypto/caam/desc_constr.h
> index 62ce6421bb3f..824c94d44f94 100644
> --- a/drivers/crypto/caam/desc_constr.h
> +++ b/drivers/crypto/caam/desc_constr.h
> @@ -163,7 +163,8 @@ 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 */
> + /* Avoid gcc warning: memcpy with data == NULL */
> + if (!IS_ENABLED(CONFIG_CRYPTO_DEV_FSL_CAAM_DEBUG) || data)

I just tried: For me a plain

if (data)

is also enough to make both gcc and sparse happy.

(On a related note, sparse reports:

CHECK drivers/crypto/caam/jr.c
drivers/crypto/caam/jr.c: note: in included file (through arch/arm64/include/asm/io.h, include/linux/io.h, include/linux/irq.h, ...):
include/asm-generic/io.h:290:22: warning: incorrect type in argument 1 (different base types)
include/asm-generic/io.h:290:22: expected unsigned long long [usertype] val
include/asm-generic/io.h:290:22: got restricted __le64 [usertype]
include/asm-generic/io.h:290:22: warning: incorrect type in argument 1 (different base types)
include/asm-generic/io.h:290:22: expected unsigned long long [usertype] val
include/asm-generic/io.h:290:22: got restricted __le64 [usertype]

Didn't look into that though.)

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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