Re: [PATCH] resource: harden resource_contains

[Alejandro Lucero Palau <alucerop@amd.com>]

On 12/4/24 23:24, Bjorn Helgaas wrote:
> 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>


Thanks!


>> ---
>>   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
>>