[PATCH] resource: harden resource_contains

[<alucerop@amd.com>]

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>
---
 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