Re: [PATCH] resource: harden resource_contains

[Bjorn Helgaas <helgaas@kernel.org>]

On Fri, Nov 29, 2024 at 09:15:12AM +0000, alucerop@amd.com wrote:
> From: Alejandro Lucero <alucerop@amd.com>
> 
> While resource_contains checks for IORESOURCE_UNSET flag for the
> resources given, if r1 was initialized with 0 size, the function
> returns a false positive. This is so because resource start and
> end fields are unsigned with end initialised to size - 1 by current
> resource macros.
> 
> Make the function to check for the resource size for both resources
> since r2 with size 0 should not be considered as valid for the function
> purpose.
> 
> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
> Suggested-by: Alison Schofield <alison.schofield@intel.com>

Seems reasonable to me.  FWIW,

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  include/linux/ioport.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index 6e9fb667a1c5..6cb8a8494508 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -264,6 +264,8 @@ static inline unsigned long resource_ext_type(const struct resource *res)
>  /* True iff r1 completely contains r2 */
>  static inline bool resource_contains(const struct resource *r1, const struct resource *r2)
>  {
> +	if (!resource_size(r1) || !resource_size(r2))
> +		return false;
>  	if (resource_type(r1) != resource_type(r2))
>  		return false;
>  	if (r1->flags & IORESOURCE_UNSET || r2->flags & IORESOURCE_UNSET)
> -- 
> 2.17.1
>