Re: [PATCH] firmware: arm_ffa: Fix warning caused by export_uuid()

[Sudeep Holla <sudeep.holla@arm.com>]

On Mon, Oct 14, 2024 at 08:25:54PM +1000, Gavin Shan wrote:
> On 10/14/24 8:08 PM, Sudeep Holla wrote:
> > On Mon, Oct 14, 2024 at 10:47:24AM +1000, Gavin Shan wrote:
> > > Run into build warning caused by export_uuid() where the UUID's
> > > length exceeds that of ffa_value_t::a2, as the following warning
> > > messages indicate.
> > > 
> > > 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);
> > >      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > 
> > > Fix it by not passing a plain buffer to memcpy() to avoid the overflow
> > > and underflow warning, similar to what have been done to copy over the
> > > struct ffa_send_direct_data2.
> > > 
> > 
> > Are you observing this just on the upstream or -next as well? There is a
> > fix in the -next which I haven't sent to soc team yet, will do so soon.
> > 
> 
> I just tried the upstream when the patch was posted. I just have a try with -next
> and similar error exists.
> 
> [root@nvidia-grace-hopper-01 linux-next]# git remote -v
> origin	git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git (fetch)
> origin	git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git (push)
> [root@nvidia-grace-hopper-01 linux-next]# make W=1 drivers/firmware/arm_ffa/driver.o
>    :
> In function ‘fortify_memcpy_chk’,
>     inlined from ‘ffa_msg_send_direct_req2’ at drivers/firmware/arm_ffa/driver.c:504:3:
> ./include/linux/fortify-string.h:580:25: error: call to ‘__read_overflow2_field’ declared with attribute warning: \
> detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror=attribute-warning]
>   580 |                         __read_overflow2_field(q_size_field, size);
>       |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
> 
> 
> Part of the changes included this patch is still needed by -next. Could you please
> squeeze the changes to that one to be pulled?

Sure I can do that. Can you share the build command(specifically if any
extra warning are enabled) and the toolchain used ? I am unable to reproduce
it with clang 20.0.0, not sure if it my toolchain or build command/flags that
differs here.

--
Regards,
Sudeep