Re: Linux 5.15

[Guenter Roeck]

On 11/1/21 1:13 AM, Geert Uytterhoeven wrote:
> Hi Günter.
>
> On Mon, Nov 1, 2021 at 1:28 AM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> > On Sun, Oct 31, 2021 at 02:09:07PM -0700, Linus Torvalds wrote:
> > Building m68k:allmodconfig ... failed
> > --------------
> > Error log:
> > In file included from include/linux/string.h:20,
> >                   from include/linux/bitmap.h:10,
> >                   from include/linux/cpumask.h:12,
> >                   from include/linux/smp.h:13,
> >                   from include/linux/lockdep.h:14,
> >                   from include/linux/spinlock.h:63,
> >                   from include/linux/mmzone.h:8,
> >                   from include/linux/gfp.h:6,
> >                   from include/linux/slab.h:15,
> >                   from drivers/nvme/target/discovery.c:7:
> > In function 'memcpy_and_pad',
> >      inlined from 'nvmet_execute_disc_identify' at drivers/nvme/target/discovery.c:268:2:
> > arch/m68k/include/asm/string.h:72:25: error: '__builtin_memcpy' reading 8 bytes from a region of size 7
> >
> > Another instance of the same problem:
> >
> > In function 'memcpy_and_pad',
> >      inlined from 'nvmet_execute_identify_ctrl' at drivers/nvme/target/admin-cmd.c:372:2:
> > arch/m68k/include/asm/string.h:72:25: error: '__builtin_memcpy' reading 8 bytes from a region of size 7
> >
> > This is seen with gcc 11.1 and 11.2. gcc 10.3 builds fine.
> > The code in question is
> >
> >          memcpy_and_pad(id->fr, sizeof(id->fr),
> >                         UTS_RELEASE, strlen(UTS_RELEASE), ' ');
> >
> > and UTS_RELEASE is "5.15.0". I have no idea what might be wrong with the code.
>
> Me neither.  That warning (now error) has been seen with all point
> releases (i.e. strlen(UTS_RELEASE) < 8) since v5.0.

Ah yes, I can see that now. I guess I didn't notice earlier because it was
only reported as warning.

> > Does anyone have an idea ?
>
> We had a discussion in
> https://lore.kernel.org/all/CAMuHMdX365qmWiii=gQLADpW49EMkdDrVJDPWNBpAZuZM0WQFQ@xxxxxxxxxxxxxx
> but without any definitive conclusion.
>
> > Do I need to revert to gcc 10.3 for m68k ?
>
> I'm not sure that might help, as the issue has been seen with
> e.g. 8.1.0 and 8.2.0, too, with a slightly different message:
> warning: ‘__builtin_memcpy’ forming offset 8 is out of the bounds [0,
> 7] [-Warray-bounds]
>
> Any suggestions? Thanks!

Replacing "strlen(UTS_RELEASE)" with "sizeof(UTS_RELEASE) - 1" seems to do
the trick, at least with gcc 11.2 and v5.15. I just wonder if that would be
acceptable. Any idea ?

Thanks,
Guenter