Re: [PATCH v3 2/4] platform/x86: hp-bioscfg: bound ordered-list parsing by the package count

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Wed, 8 Jul 2026, Muhammad Bilal wrote:

> hp_populate_ordered_list_elements_from_package() differs from the other
> per-type parsers: its main loop is bounded only by the fixed per-type
> count and never checks elem against the number of elements actually
> present in the package,
> 
>   for (elem = 1, eloc = 1; eloc < ORD_ELEM_CNT; elem++, eloc++)
> 
> whereas the string, integer, enumeration and password parsers bound
> their main loop with "elem < count" as well.
> 
> This is safe today because hp_init_bios_package_attribute() rejects any
> package with fewer than ORD_ELEM_CNT elements before the parser runs. A
> later patch relaxes that check to accept shorter packages; 

An upcoming change, however, relaxes ...

> once this
> loop can be handed fewer than ORD_ELEM_CNT elements it indexes
> order_obj[elem] past the end of the array - an out-of-bounds heap read.

I don't think we need this part of the explanation, it will never happen 
as you're fixing it beforehand. :-) So please drop it as unnecessary 
detail.

It's pretty obvious to kernel developers anyway if there's a runaway index 
so there's no big need in general to tell too simple basics like that.

> Bound the loop by the validated element count as well, so it stops at
> whichever comes first, the per-type count or the real package size,
> 
>   for (elem = 1, eloc = 1; eloc < ORD_ELEM_CNT && elem < order_obj_count;
>        elem++, eloc++)
> 
> order_obj_count is the validated count plumbed in by the previous
> patch. No functional change for packages that enumerate correctly
> today.
> 
> Fixes: a34fc329b189 ("platform/x86: hp-bioscfg: bioscfg")
> Cc: stable@vger.kernel.org
> Signed-off-by: Muhammad Bilal <meatuni001@gmail.com>
> ---
>  drivers/platform/x86/hp/hp-bioscfg/order-list-attributes.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/hp/hp-bioscfg/order-list-attributes.c b/drivers/platform/x86/hp/hp-bioscfg/order-list-attributes.c
> index 83ddf99f93954..a50d074125268 100644
> --- a/drivers/platform/x86/hp/hp-bioscfg/order-list-attributes.c
> +++ b/drivers/platform/x86/hp/hp-bioscfg/order-list-attributes.c
> @@ -145,7 +145,7 @@ static int hp_populate_ordered_list_elements_from_package(union acpi_object *ord
>  	if (!order_obj)
>  		return -EINVAL;
>  
> -	for (elem = 1, eloc = 1; eloc < ORD_ELEM_CNT; elem++, eloc++) {
> +	for (elem = 1, eloc = 1; eloc < ORD_ELEM_CNT && elem < order_obj_count; elem++, eloc++) {
>  
>  		switch (order_obj[elem].type) {
>  		case ACPI_TYPE_STRING:
> 

-- 
 i.