[PATCH 5.11 244/601] platform/x86: dell-wmi-sysman: Make init_bios_attributes() ACPI object parsing more robust

Greg Kroah-Hartman
2021-05-12T17:22:01Z

From: Hans de Goede <hdegoede@redhat.com>

[ Upstream commit 5e3f5973c8dfd2b80268f1825ed2f2ddf81d3267 ]

Make init_bios_attributes() ACPI object parsing more robust:
1. Always check that the type of the return ACPI object is package, rather
then only checking this for instance_id == 0
2. Check that the package has the minimum amount of elements which will
be consumed by the populate_foo_data() for the attr_type

Note/TODO: The populate_foo_data() functions should also be made more
robust. The should check the type of each of the elements matches the
type which they expect and in case of populate_enum_data()
obj->package.count should be passed to it as an argument and it should
re-check this itself since it consume a variable number of elements.

Fixes: e8a60aa7404b ("platform/x86: Introduce support for Systems Management Driver over WMI for Dell Systems")
Cc: Divya Bharathi <Divya_Bharathi@dell.com>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210321121607.35717-1-hdegoede@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/platform/x86/dell-wmi-sysman/sysman.c | 32 ++++++++++++++++---
1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/x86/dell-wmi-sysman/sysman.c b/drivers/platform/x86/dell-wmi-sysman/sysman.c
index 7410ccae650c..a90ae6ba4a73 100644
--- a/drivers/platform/x86/dell-wmi-sysman/sysman.c
+++ b/drivers/platform/x86/dell-wmi-sysman/sysman.c
@@ -399,6 +399,7 @@ static int init_bios_attributes(int attr_type, const char *guid)
union acpi_object *obj = NULL;
union acpi_object *elements;
struct kset *tmp_set;
+ int min_elements;

/* instance_id needs to be reset for each type GUID
* also, instance IDs are unique within GUID but not across
@@ -409,14 +410,38 @@ static int init_bios_attributes(int attr_type, const char *guid)
retval = alloc_attributes_data(attr_type);
if (retval)
return retval;
+
+ switch (attr_type) {
+ case ENUM: min_elements = 8; break;
+ case INT: min_elements = 9; break;
+ case STR: min_elements = 8; break;
+ case PO: min_elements = 4; break;
+ default:
+ pr_err("Error: Unknown attr_type: %d\n", attr_type);
+ return -EINVAL;
+ }
+
/* need to use specific instance_id and guid combination to get right data */
obj = get_wmiobj_pointer(instance_id, guid);
- if (!obj || obj->type != ACPI_TYPE_PACKAGE)
+ if (!obj)
return -ENODEV;
- elements = obj->package.elements;

mutex_lock(&wmi_priv.mutex);
- while (elements) {
+ while (obj) {
+ if (obj->type != ACPI_TYPE_PACKAGE) {
+ pr_err("Error: Expected ACPI-package type, got: %d\n", obj->type);
+ retval = -EIO;
+ goto err_attr_init;
+ }
+
+ if (obj->package.count < min_elements) {
+ pr_err("Error: ACPI-package does not have enough elements: %d < %d\n",
+ obj->package.count, min_elements);
+ goto nextobj;
+ }
+
+ elements = obj->package.elements;
+
/* sanity checking */
if (elements[ATTR_NAME].type != ACPI_TYPE_STRING) {
pr_debug("incorrect element type\n");
@@ -481,7 +506,6 @@ nextobj:
kfree(obj);
instance_id++;
obj = get_wmiobj_pointer(instance_id, guid);
- elements = obj ? obj->package.elements : NULL;
}

mutex_unlock(&wmi_priv.mutex);
--
2.30.2