linux-kernel - Re: [PATCH] firmware: arm_ffa: avoid string-fortify warningn in export

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Message-ID: <ZuGl3v0y4SYR1np7@bogus>
Date: Wed, 11 Sep 2024 15:14:54 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: Arnd Bergmann <arnd@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>,
	Cristian Marussi <cristian.marussi@....com>,
	Jens Wiklander <jens.wiklander@...aro.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] firmware: arm_ffa: avoid string-fortify warningn in
 export_uuid()

On Mon, Sep 09, 2024 at 11:09:24AM +0000, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> Copying to a 16 byte structure into an 8-byte struct member
> causes a compile-time warning:
> 
> In file included from drivers/firmware/arm_ffa/driver.c:25:
> In function 'fortify_memcpy_chk',
>     inlined from 'export_uuid' at include/linux/uuid.h:88:2,
>     inlined from 'ffa_msg_send_direct_req2' at drivers/firmware/arm_ffa/driver.c:488:2:
> include/linux/fortify-string.h:571:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
>   571 |                         __write_overflow_field(p_size_field, size);
>       |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Use a union for the conversion instead and make sure the byte order
> is fixed in the process.
> 

Thanks for spotting and fixing the issue. I tested enabling
CONFIG_FORTIFY_SOURCE but couldn't hit this with gcc 13 and clang 20

Also do you want this sent as fix on top of my FF-A PR now or after -rc1 ?

--
Regards,
Sudeep