can: ucan: Replace zero-length array with DECLARE_FLEX_ARRAY() helper

[PATCH][next] can: ucan: Replace zero-length array with DECLARE_FLEX_ARRAY() helper

Posted by Gustavo A. R. Silva 3 years, 6 months ago

Zero-length arrays are deprecated and we are moving towards adopting
C99 flexible-array members, instead. So, replace zero-length arrays
declarations in anonymous union with the new DECLARE_FLEX_ARRAY()
helper macro.

This helper allows for flexible-array members in unions.

Link: https://github.com/KSPP/linux/issues/193
Link: https://github.com/KSPP/linux/issues/214
Link: https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/net/can/usb/ucan.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/usb/ucan.c b/drivers/net/can/usb/ucan.c
index 7c35f50fda4e..b53e709943bc 100644
--- a/drivers/net/can/usb/ucan.c
+++ b/drivers/net/can/usb/ucan.c
@@ -245,7 +245,8 @@ struct ucan_message_in {
 		/* CAN transmission complete
 		 * (type == UCAN_IN_TX_COMPLETE)
 		 */
-		struct ucan_tx_complete_entry_t can_tx_complete_msg[0];
+		DECLARE_FLEX_ARRAY(struct ucan_tx_complete_entry_t,
+				   can_tx_complete_msg);
 	} __aligned(0x4) msg;
 } __packed __aligned(0x4);
 
-- 
2.34.1

Re: [PATCH][next] can: ucan: Replace zero-length array with DECLARE_FLEX_ARRAY() helper

Posted by Marc Kleine-Budde 3 years, 6 months ago

On 26.09.2022 16:43:56, Gustavo A. R. Silva wrote:
> Zero-length arrays are deprecated and we are moving towards adopting
> C99 flexible-array members, instead. So, replace zero-length arrays
> declarations in anonymous union with the new DECLARE_FLEX_ARRAY()
> helper macro.
> 
> This helper allows for flexible-array members in unions.
> 
> Link: https://github.com/KSPP/linux/issues/193
> Link: https://github.com/KSPP/linux/issues/214
> Link: https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Applied to linux-can-next.

Thanks,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
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Re: [PATCH][next] can: ucan: Replace zero-length array with DECLARE_FLEX_ARRAY() helper

Posted by Kees Cook 3 years, 6 months ago

On Mon, Sep 26, 2022 at 04:43:56PM -0500, Gustavo A. R. Silva wrote:
> Zero-length arrays are deprecated and we are moving towards adopting
> C99 flexible-array members, instead. So, replace zero-length arrays
> declarations in anonymous union with the new DECLARE_FLEX_ARRAY()
> helper macro.
> 
> This helper allows for flexible-array members in unions.
> 
> Link: https://github.com/KSPP/linux/issues/193
> Link: https://github.com/KSPP/linux/issues/214
> Link: https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook