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

[Limonciello, Mario]

+Divya, +Prasanth, +Perry

> -----Original Message-----
> From: Limonciello, Mario <Mario_Limonciello@xxxxxxxx>
> Sent: Friday, January 29, 2021 11:27
> To: Hans De Goede; Mark Gross
> Cc: LKML; platform-driver-x86@xxxxxxxxxxxxxxx; Limonciello, Mario
> Subject: [PATCH] platform/x86: dell-wmi-sysman: fix a NULL pointer dereference
> 
> 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.limonciello@xxxxxxxx>
> ---
>  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