linux-kernel - Re: drivers/acpi/acpica/tbfind.c:60:9: error: 'strncpy' specified bound 6 equals destination size

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Date:   Thu, 13 Apr 2023 09:54:26 +0800
From:   Yujie Liu <yujie.liu@...el.com>
To:     Catalin Marinas <catalin.marinas@....com>
CC:     kernel test robot <lkp@...el.com>,
        Mark Rutland <mark.rutland@....com>,
        <oe-kbuild-all@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
        <linux-acpi@...r.kernel.org>
Subject: Re: drivers/acpi/acpica/tbfind.c:60:9: error: 'strncpy' specified
 bound 6 equals destination size

On Tue, Apr 11, 2023 at 12:13:55PM +0100, Catalin Marinas wrote:
> On Fri, Apr 07, 2023 at 03:02:15PM +0800, kernel test robot wrote:
> > FYI, the error/warning still remains.
> > 
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head:   f2afccfefe7be1f7346564fe619277110d341f9b
> > commit: 8f9e0a52810dd83406c768972d022c37e7a18f1f ACPI: Don't build ACPICA with '-Os'
> > date:   2 months ago
> > config: x86_64-sof-customedconfig-fuzz-defconfig (https://download.01.org/0day-ci/archive/20230407/202304071552.CeeIBr5P-lkp@intel.com/config)
> > compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
> > reproduce (this is a W=1 build):
> >         # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8f9e0a52810dd83406c768972d022c37e7a18f1f
> >         git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> >         git fetch --no-tags linus master
> >         git checkout 8f9e0a52810dd83406c768972d022c37e7a18f1f
> >         # save the config file
> >         mkdir build_dir && cp config build_dir/.config
> >         make W=1 O=build_dir ARCH=x86_64 olddefconfig
> >         make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash
> > 
> > If you fix the issue, kindly add following tag where applicable
> > | Reported-by: kernel test robot <lkp@...el.com>
> > | Link: https://lore.kernel.org/oe-kbuild-all/202304071552.CeeIBr5P-lkp@intel.com/
> > 
> > All errors (new ones prefixed by >>):
> > 
> >    drivers/acpi/acpica/tbfind.c: In function 'acpi_tb_find_table':
> > >> drivers/acpi/acpica/tbfind.c:60:9: error: 'strncpy' specified bound 6 equals destination size [-Werror=stringop-truncation]
> >       60 |         strncpy(header.oem_id, oem_id, ACPI_OEM_ID_SIZE);
> >          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >    drivers/acpi/acpica/tbfind.c:61:9: error: 'strncpy' specified bound 8 equals destination size [-Werror=stringop-truncation]
> >       61 |         strncpy(header.oem_table_id, oem_table_id, ACPI_OEM_TABLE_ID_SIZE);
> >          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >    cc1: all warnings being treated as errors
> 
> I think the kernel test robot should filter out any reports related to
> this commit. The warning has nothing to do with the -O2 vs -Os change.
> It's simply that the compiler now warns if strncpy() has the destination
> size equal to the bound parameter (for some reason it doesn't do this
> with -Os). I mentioned it on a different report here:
> 
> https://lore.kernel.org/all/Y%2FdM77YdzDKRDdj1@arm.com/
> 
> A potential solution to silence the compiler is to go through the ACPI
> code and change those strncpy() instances to memcpy(). I don't think
> those strings are even null-terminated in the APCI spec, so using
> strncpy() doesn't make sense.

Sorry for making this noise. We've configured the robot to filter out
the reports related to this commit.

--
Best Regards,
Yujie