Subject: Re: [PATCH v8 10/27] resource: harden resource_contains

From: Jonathan Cameron <[email-masked]>
Date: Tue, 24 Dec 2024 17:27:57 +0000

On Mon, 16 Dec 2024 16:10:25 +0000
<[email-masked]> wrote:

> From: Alejandro Lucero <[email-masked]>
> 
> 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 <[email-masked]>
> Suggested-by: Alison Schofield <[email-masked]>
> Reviewed-by: Alison Schofield <[email-masked]>
> Acked-by: Bjorn Helgaas <[email-masked]>
Seems sensible.
Reviewed-by: Jonathan Cameron <[email-masked]>

> ---
>  include/linux/ioport.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index 5385349f0b8a..7ba31a222536 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -296,6 +296,8 @@ 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)