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

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->mapping to replace uacce->inode->i_mapping.

Signed-off-by: Weili Qian qianweili@huawei.com Signed-off-by: Zhangfei Gao zhangfei.gao@linaro.org --- drivers/misc/uacce/uacce.c | 14 +++++++------- include/linux/uacce.h | 4 ++-- 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c index 346bd7cf2e94..338b59ef5493 100644 --- a/drivers/misc/uacce/uacce.c +++ b/drivers/misc/uacce/uacce.c @@ -166,8 +166,8 @@ static int uacce_fops_open(struct inode *inode, struct file *filep)

init_waitqueue_head(&q->wait); filep->private_data = q; - uacce->inode = inode; q->state = UACCE_Q_INIT; + q->mapping = filep->f_mapping; mutex_init(&q->mutex); list_add(&q->list, &uacce->queues); mutex_unlock(&uacce->mutex); @@ -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 @@ -597,6 +591,12 @@ 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(q->mapping, 0, 0, 1); }

/* disable sva now since no opened queues */ diff --git a/include/linux/uacce.h b/include/linux/uacce.h index 0a81c3dfd26c..e290c0269944 100644 --- a/include/linux/uacce.h +++ b/include/linux/uacce.h @@ -86,6 +86,7 @@ enum uacce_q_state { * @state: queue state machine * @pasid: pasid associated to the mm * @handle: iommu_sva handle returned by iommu_sva_bind_device() + * @mapping: user space mapping of the queue */ struct uacce_queue { struct uacce_device *uacce; @@ -97,6 +98,7 @@ struct uacce_queue { enum uacce_q_state state; u32 pasid; struct iommu_sva *handle; + struct address_space *mapping; };

/** @@ -114,7 +116,6 @@ struct uacce_queue { * @mutex: protects uacce operation * @priv: private pointer of the uacce * @queues: list of queues - * @inode: core vfs */ struct uacce_device { const char *algs; @@ -130,7 +131,6 @@ struct uacce_device { struct mutex mutex; void *priv; struct list_head queues; - struct inode *inode; };

#if IS_ENABLED(CONFIG_UACCE)