Re: [PATCH] i2c: atr: annotate i2c_atr_adap_desc->aliases with __counted_by_ptr

[Rosen Penev]

On Tue, Apr 28, 2026 at 2:30 AM Luca Ceresoli <luca.ceresoli@xxxxxxxxxxx> wrote:
>
> Hello Thorsten,
>
> +Cc Romain, author of the involved code
> +Cc Rosen, author of a similar patch elsewhere in i2c-atr [0]
>
> [0] https://lore.kernel.org/linux-i2c/20260327030310.8502-1-rosenp@xxxxxxxxx/
>
> On Mon Apr 27, 2026 at 7:28 PM CEST, Thorsten Blum wrote:
> > Add the __counted_by_ptr() compiler attribute to ->aliases to improve
> > bounds checking via CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE.
> >
> > Signed-off-by: Thorsten Blum <thorsten.blum@xxxxxxxxx>
> > ---
> >  include/linux/i2c-atr.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/linux/i2c-atr.h b/include/linux/i2c-atr.h
> > index 2bb54dc87c8e..b52a7b9ec536 100644
> > --- a/include/linux/i2c-atr.h
> > +++ b/include/linux/i2c-atr.h
> > @@ -71,7 +71,7 @@ struct i2c_atr_adap_desc {
> >       struct device *parent;
> >       struct fwnode_handle *bus_handle;
> >       size_t num_aliases;
> > -     u16 *aliases;
> > +     u16 *aliases __counted_by_ptr(num_aliases);
>
> I'm not fully proficient about all counted_by things, but the patch looks
> OK to me, and definitely @num_aliases is the number of items @aliases must
> have, so:
I prefer my patch.

__counted_by is supported by more versions of GCC/Clang than __counted_by_ptr.
>
> Reviewed-by: Luca Ceresoli <luca.ceresoli@xxxxxxxxxxx>
>
> --
> Luca Ceresoli, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com