[PATCH RFC 08/15] arm_mpam: Fix ris_idx type to prevent range check bypass on truncation

[Yin Li]

The RIS index is read from device tree as u64 via of_property_read_reg(),
but was narrowed to u32 when passed to mpam_dt_parse_resource() and
further to u8 when passed to mpam_ris_create(). A value exceeding
MPAM_MSC_MAX_NUM_RIS could be silently truncated to a small index that
passes the range check in mpam_ris_create_locked(), leading to incorrect
RIS creation.

Widen the ris_idx parameter through mpam_dt_parse_resource(),
mpam_ris_create_locked(), and mpam_ris_create() to u64 so the value
is preserved until the range check in mpam_ris_create_locked() rejects
out-of-range indices.

Signed-off-by: Yin Li <yin.li@xxxxxxxxxxxxxxxx>
---
 drivers/resctrl/mpam_devices.c | 6 +++---
 include/linux/arm_mpam.h       | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index cc9fa1d78925..1e082fb60e30 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -260,7 +260,7 @@ static int mpam_dt_count_msc(void)
 }
 
 static int mpam_dt_parse_resource(struct mpam_msc *msc, struct device_node *np,
-				  u32 ris_idx)
+				  u64 ris_idx)
 {
 	int err = 0;
 	u32 class_id = 0;
@@ -712,7 +712,7 @@ static int mpam_ris_get_affinity(struct mpam_msc *msc, cpumask_t *affinity,
 	return 0;
 }
 
-static int mpam_ris_create_locked(struct mpam_msc *msc, u8 ris_idx,
+static int mpam_ris_create_locked(struct mpam_msc *msc, u64 ris_idx,
 				  enum mpam_class_types type, u8 class_id,
 				  int component_id)
 {
@@ -799,7 +799,7 @@ static void mpam_ris_destroy(struct mpam_msc_ris *ris)
 		mpam_vmsc_destroy(vmsc);
 }
 
-int mpam_ris_create(struct mpam_msc *msc, u8 ris_idx,
+int mpam_ris_create(struct mpam_msc *msc, u64 ris_idx,
 		    enum mpam_class_types type, u8 class_id, int component_id)
 {
 	int err;
diff --git a/include/linux/arm_mpam.h b/include/linux/arm_mpam.h
index f92a36187a52..30461cd71199 100644
--- a/include/linux/arm_mpam.h
+++ b/include/linux/arm_mpam.h
@@ -39,10 +39,10 @@ static inline int acpi_mpam_count_msc(void) { return -EINVAL; }
 #endif
 
 #ifdef CONFIG_ARM64_MPAM_DRIVER
-int mpam_ris_create(struct mpam_msc *msc, u8 ris_idx,
+int mpam_ris_create(struct mpam_msc *msc, u64 ris_idx,
 		    enum mpam_class_types type, u8 class_id, int component_id);
 #else
-static inline int mpam_ris_create(struct mpam_msc *msc, u8 ris_idx,
+static inline int mpam_ris_create(struct mpam_msc *msc, u64 ris_idx,
 				  enum mpam_class_types type, u8 class_id,
 				  int component_id)
 {

-- 
2.34.1