On Thu, May 11, 2023 at 10:15:53AM +0800, Zhangfei Gao wrote:
> The inode can be different in a container, for example, a docker and host
> both open the same uacce parent device, which uses the same uacce struct
> but different inode, so uacce->inode is not enough.
>
> What's worse, when docker stops, the inode will be destroyed as well,
> causing use-after-free in uacce_remove.
>
> So use q->filep->f_mapping to replace uacce->inode->i_mapping.
> @@ -574,12 +574,6 @@ void uacce_remove(struct uacce_device *uacce)
>
> if (!uacce)
> return;
> - /*
> - * unmap remaining mapping from user space, preventing user still
> - * access the mmaped area while parent device is already removed
> - */
> - if (uacce->inode)
> - unmap_mapping_range(uacce->inode->i_mapping, 0, 0, 1);
>
> /*
> * uacce_fops_open() may be running concurrently, even after we remove
> @@ -589,6 +583,8 @@ void uacce_remove(struct uacce_device *uacce)
> mutex_lock(&uacce->mutex);
> /* ensure no open queue remains */
> list_for_each_entry_safe(q, next_q, &uacce->queues, list) {
> + struct file *filep = q->private_data;
> +
> /*
> * Taking q->mutex ensures that fops do not use the defunct
> * uacce->ops after the queue is disabled.
> @@ -597,6 +593,12 @@ void uacce_remove(struct uacce_device *uacce)
> uacce_put_queue(q);
> mutex_unlock(&q->mutex);
> uacce_unbind_queue(q);
> +
> + /*
> + * unmap remaining mapping from user space, preventing user still
> + * access the mmaped area while parent device is already removed
> + */
> + unmap_mapping_range(filep->f_mapping, 0, 0, 1);
IDGI. Going through uacce_queue instead of uacce_device is fine, but why
bother with file *or* inode? Just store a reference to struct address_space in
your uacce_queue and be done with that...
Another problem in that driver is uacce_vma_close(); this
if (vma->vm_pgoff < UACCE_MAX_REGION)
qfr = q->qfrs[vma->vm_pgoff];
kfree(qfr);
can't be right - you have q->qfrs left pointing to freed object. If nothing
else, subsequent mmap() will fail with -EEXIST, won't it?
