Hi Kees,
On Sat, 26 Apr 2025 at 13:33, Helge Deller <del...@gmx.de> wrote:
> On 4/26/25 08:23, Kees Cook wrote:
> > In preparation for making the kmalloc family of allocators type aware,
> > we need to make sure that the returned type from the allocation matches
> > the type of the variable being assigned. (Before, the allocator would
> > always return "void *", which can be implicitly cast to any pointer type.)
> >
> > The assigned type is "struct dac_info *" but the returned type will be
> > "struct ics5342_info *", which has a larger allocation size. This is
> > by design, as struct ics5342_info contains struct dac_info as its first
> > member. Cast the allocation type to match the assignment.
> >
> > Signed-off-by: Kees Cook <k...@kernel.org>
Thanks for your patch, which is now commit 8d2f0f5bbac87b9d ("fbdev:
arkfb: Cast ics5342_init() allocation type") in fbdev/for-next.
> I applied your patch, but wouldn't this untested patch be cleaner and fulfill
> the
> same purpose to match a kzalloc return type?
>
> diff --git a/drivers/video/fbdev/arkfb.c b/drivers/video/fbdev/arkfb.c
> index 7d131e3d159a..a57c8a992e11 100644
> --- a/drivers/video/fbdev/arkfb.c
> +++ b/drivers/video/fbdev/arkfb.c
> @@ -431,7 +431,8 @@ static struct dac_ops ics5342_ops = {
>
> static struct dac_info * ics5342_init(dac_read_regs_t drr, dac_write_regs_t
> dwr, void *data)
> {
> - struct dac_info *info = (struct dac_info *)kzalloc(sizeof(struct
> ics5342_info), GFP_KERNEL);
> + struct ics5342_info *ics_info = kzalloc(sizeof(struct ics5342_info),
> GFP_KERNEL);
sizeof(*ics_info)?
> + struct dac_info *info = &ics_info->dac;
Exactly my thought when I noticed this commit. Adding casts makes
it harder to notice any future discrepancies.
> > --- a/drivers/video/fbdev/arkfb.c
> > +++ b/drivers/video/fbdev/arkfb.c
> > @@ -431,7 +431,7 @@ static struct dac_ops ics5342_ops = {
> >
> > static struct dac_info * ics5342_init(dac_read_regs_t drr,
> > dac_write_regs_t dwr, void *data)
> > {
> > - struct dac_info *info = kzalloc(sizeof(struct ics5342_info),
> > GFP_KERNEL);
> > + struct dac_info *info = (struct dac_info *)kzalloc(sizeof(struct
> > ics5342_info), GFP_KERNEL);
> >
> > if (! info)
> > return NULL;
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
