[PATCH] platform/x86: dell-wmi-sysman: fix a NULL pointer dereference

[Mario Limonciello]

An upcoming Dell platform is causing a NULL pointer dereference
in dell-wmi-sysman initialization.  Validate that the input from
BIOS matches correct ACPI types and abort module initialization
if it fails.

This leads to a memory leak that needs to be cleaned up properly.

Signed-off-by: Mario Limonciello <mario.limoncie...@dell.com>
---
 drivers/platform/x86/dell-wmi-sysman/sysman.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/dell-wmi-sysman/sysman.c 
b/drivers/platform/x86/dell-wmi-sysman/sysman.c
index dc6dd531c996..38b497991071 100644
--- a/drivers/platform/x86/dell-wmi-sysman/sysman.c
+++ b/drivers/platform/x86/dell-wmi-sysman/sysman.c
@@ -419,13 +419,19 @@ static int init_bios_attributes(int attr_type, const char 
*guid)
                return retval;
        /* need to use specific instance_id and guid combination to get right 
data */
        obj = get_wmiobj_pointer(instance_id, guid);
-       if (!obj)
+       if (!obj || obj->type != ACPI_TYPE_PACKAGE) {
+               release_attributes_data();
                return -ENODEV;
+       }
        elements = obj->package.elements;
 
        mutex_lock(&wmi_priv.mutex);
        while (elements) {
                /* sanity checking */
+               if (elements[ATTR_NAME].type != ACPI_TYPE_STRING) {
+                       pr_debug("incorrect element type\n");
+                       goto nextobj;
+               }
                if (strlen(elements[ATTR_NAME].string.pointer) == 0) {
                        pr_debug("empty attribute found\n");
                        goto nextobj;
-- 
2.25.1