[PATCH v2 1/4] platform/x86/amd/hsmp: Validate ACPI UID before parsing socket index

[Muralidhara M K]

hsmp_get_uid() passed the device UID directly to kstrtou16(uid + 2)
without checking it.  A NULL UID or one shorter than three characters
would dereference a NULL pointer or read past the end of the string.

Reject such UIDs with -EINVAL before stripping the "ID" prefix.

Signed-off-by: Muralidhara M K <muralidhara.mk@xxxxxxx>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Link: https://patch.msgid.link/20260625123337.886435-3-muralidhara.mk@xxxxxxx
---
 drivers/platform/x86/amd/hsmp/acpi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
index 97ed71593bdf..4a1ce4cb25e7 100644
--- a/drivers/platform/x86/amd/hsmp/acpi.c
+++ b/drivers/platform/x86/amd/hsmp/acpi.c
@@ -21,6 +21,7 @@
 #include <linux/kstrtox.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/string.h>
 #include <linux/sysfs.h>
 #include <linux/topology.h>
 #include <linux/uuid.h>
@@ -77,6 +78,8 @@ static inline int hsmp_get_uid(struct device *dev, u16 *sock_ind)
 	 * bytes to integer.
 	 */
 	uid = acpi_device_uid(ACPI_COMPANION(dev));
+	if (!uid || strlen(uid) < 3)
+		return -EINVAL;
 
 	return kstrtou16(uid + 2, 10, sock_ind);
 }
-- 
2.43.0