[PATCH] uacce: use filep->f_mapping to replace inode->i_mapping

[Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>]

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.

Signed-off-by: Weili Qian <qianweili@xxxxxxxxxx>
Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
---
 drivers/misc/uacce/uacce.c | 16 +++++++++-------
 include/linux/uacce.h      |  4 ++--
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
index 346bd7cf2e94..740ace422baa 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->private_data = filep;
 	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
@@ -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);
 	}
 
 	/* disable sva now since no opened queues */
diff --git a/include/linux/uacce.h b/include/linux/uacce.h
index 0a81c3dfd26c..64b800b74436 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()
+ * @private_data: private data for saving filep
  */
 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;
+	void *private_data;
 };
 
 /**
@@ -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)
-- 
2.39.2 (Apple Git-143)