On Thu, 11 May 2023 at 12:05, Al Viro viro@zeniv.linux.org.uk 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