Re: [PATCH] Drivers: hv: vmbus: Check ACPI companion before use

[Naman Jain <namjain@linux.microsoft.com>]

On 10/17/2026 12:13 PM, Jiale Yao wrote:
> Platform drivers can be forced to bind to devices outside their match
> tables through driver_override. vmbus_acpi_add() assumes that every bound
> device has an ACPI companion and dereferences it without checking.
> 
> Return -ENODEV when the companion is absent to avoid a NULL pointer
> dereference.
> 
> Signed-off-by: Jiale Yao <yaojiale02@163.com>
> ---
>   drivers/hv/vmbus_drv.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 4692687cdbf3..28f459679406 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -2571,10 +2571,14 @@ EXPORT_SYMBOL_GPL(vmbus_free_mmio);
>   #ifdef CONFIG_ACPI
>   static int vmbus_acpi_add(struct platform_device *pdev)
>   {
> +	struct acpi_device *ancestor;
> +	struct acpi_device *device;
>   	acpi_status result;
>   	int ret_val = -ENODEV;
> -	struct acpi_device *ancestor;
> -	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
> +
> +	device = ACPI_COMPANION(&pdev->dev);
> +	if (!device)
> +		return -ENODEV;
>   
>   	vmbus_root_device = &device->dev;
>   

Reviewed-by: Naman Jain <namjain@linux.microsoft.com>

Regards,
Naman