On Thu, 11 May 2023 at 12:05, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > 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... Yes, a struct address_space is enough. > > 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? Good catch, will fix it. Thanks