Re: [PATCH v1 1/2] arm_mpam: Fix a NULL pointer dereference on unbinding after an error interrupt

[Andre Przywara]

Hi,

On 8/6/26 16:46, Ben Horgan wrote:
> If a user unbinds an MSC after mpam_disable() has been run in response
> to an error interrupt then a dereference of a NULL pointer occurs as
> mpam_disable() sets the drvdata to NULL. Add an early return to the driver
> remove callback to avoid this.

Yes, I added a very similar patch to my stack yesterday, in response to 
a Sashiko complaint.
However I was still calling mpam_free_garbage() at the end, to me it 
looks like this is not depending on any MSC?

Cheers,
Andre

> Fixes: f04046f2577a ("arm_mpam: Add probe/remove for mpam msc driver and kbuild boiler plate")
> Signed-off-by: Ben Horgan <ben.horgan@xxxxxxx>
> ---
>   drivers/resctrl/mpam_devices.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> index 2f09f4b78bd3..bc6cc0b5c96b 100644
> --- a/drivers/resctrl/mpam_devices.c
> +++ b/drivers/resctrl/mpam_devices.c
> @@ -2025,6 +2025,9 @@ static void mpam_msc_drv_remove(struct platform_device *pdev)
>   {
>   	struct mpam_msc *msc = platform_get_drvdata(pdev);
>   
> +	if (!msc)
> +		return;
> +
>   	mutex_lock(&mpam_list_lock);
>   	mpam_msc_destroy(msc);
>   	mutex_unlock(&mpam_list_lock);