Re: [PATCH] platform/x86: hp-bioscfg: zero the hex-string decode buffer in hp_convert_hexstr_to_str

[Muhammad Bilal]

Thanks, Ilpo.

Noted. I'll include the parentheses in function names in the Subject
line for future patches.

Thanks for the review and for applying the patch.

--
Muhammad


On Wed, Sep 16, 2026 at 3:29 PM Ilpo Järvinen
<ilpo.jarvinen@xxxxxxxxxxxxxxx> wrote:
>
> On Wed, 16 Sep 2026, Muhammad Bilal wrote:
>
> > hp_convert_hexstr_to_str() allocates its output buffer for the
> > worst-case decoded length, then fills in only as many bytes as the
> > input actually decodes to before shrinking the allocation down to
> > that length with krealloc(). Well-formed input can decode to
> > noticeably fewer bytes than the worst case, so the buffer is
> > frequently only partially written by the time it is realloc'd and
> > returned to the caller.
> >
> > Use kzalloc() instead of kmalloc() for the initial allocation, so
> > any unused capacity starts out zeroed instead of holding leftover
> > heap contents, rather than relying on every current and future
> > caller and code path to fill the buffer exactly.
> >
> > Suggested-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> > Signed-off-by: Muhammad Bilal <meatuni001@xxxxxxxxx>
> > ---
> > Applies on top of "platform/x86: hp-bioscfg: fix slab-out-of-bounds
> > write in hp_convert_hexstr_to_str" (the DIV_ROUND_UP sizing fix),
> > which Ilpo has applied to review-ilpo-next but is not yet in
> > mainline. Sent as its own patch rather than a v3 of that one, since
> > the sizing fix itself was applied as-is; this is the separate change
> > requested on top of it.
>
> Thanks, applied to review-ilpo-next.
>
> In future, please try to add parenthesis into function names in the
> shortlog (on Subject line) as well so I don't need to manually add them
> myself.
>
> --
>  i.
>
> > ---
> >  drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> > index ff28db7..2dab9c0 100644
> > --- a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> > +++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> > @@ -442,7 +442,7 @@ int hp_convert_hexstr_to_str(const char *input, u32 input_len, char **str, int *
> >       *len = 0;
> >       *str = NULL;
> >
> > -     new_str = kmalloc(2 * DIV_ROUND_UP(input_len, 5) + 1, GFP_KERNEL);
> > +     new_str = kzalloc(2 * DIV_ROUND_UP(input_len, 5) + 1, GFP_KERNEL);
> >       if (!new_str)
> >               return -ENOMEM;
> >
> >