On 07/05/2018 09:57 PM, xiu...@redhat.com wrote:
> static irqreturn_t uio_interrupt(int irq, void *dev_id)
> {
> struct uio_device *idev = (struct uio_device *)dev_id;
> - irqreturn_t ret = idev->info->handler(irq, idev->info);
> + irqreturn_t ret;
> +
> + mutex_lock(&idev->info_lock);
> + if (!idev->info) {
> + ret = IRQ_NONE;
> + goto out;
> + }
>
> + ret = idev->info->handler(irq, idev->info);
> if (ret == IRQ_HANDLED)
> uio_event_notify(idev->info);
>
> +out:
> + mutex_unlock(&idev->info_lock);
> return ret;
> }
Do you need the interrupt related changes in this patch and the first
one? When we do uio_unregister_device -> free_irq does free_irq return
when there are no longer running interrupt handlers that we requested?
If that is not the case then I think we can hit a similar bug. We do:
__uio_register_device -> device_register -> device's refcount goes to
zero so we do -> uio_device_release -> kfree(idev)
and if it is possible the interrupt handler could still run after
free_irq then we would end up doing:
uio_interrupt -> mutex_lock(&idev->info_lock) -> idev access freed memory.
