Hi Zhangfei,
On 2020/2/24 15:06, Zhangfei Gao wrote:
> When uacce parent device module is removed, user app may
> still keep the mmaped area, which can be accessed unsafely.
> When rmmod, Parent device drvier will call uacce_remove,
> which unmap all remaining mapping from user space for safety.
> VM_FAULT_SIGBUS is also reported to user space accordingly.
>
> Suggested-by: Dave Jiang <[email protected]>
> Signed-off-by: Zhangfei Gao <[email protected]>
> ---
> drivers/misc/uacce/uacce.c | 17 +++++++++++++++++
> include/linux/uacce.h | 2 ++
> 2 files changed, 19 insertions(+)
>
> diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
> index ffced4d..1bcc5e6 100644
> --- a/drivers/misc/uacce/uacce.c
> +++ b/drivers/misc/uacce/uacce.c
> @@ -224,6 +224,7 @@ 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;
>
> return 0;
> @@ -253,6 +254,14 @@ static int uacce_fops_release(struct inode *inode, struct file *filep)
> return 0;
> }
>
> +static vm_fault_t uacce_vma_fault(struct vm_fault *vmf)
> +{
> + if (vmf->flags & (FAULT_FLAG_MKWRITE | FAULT_FLAG_WRITE))
> + return VM_FAULT_SIGBUS;
> +
> + return 0;
> +}
> +
> static void uacce_vma_close(struct vm_area_struct *vma)
> {
> struct uacce_queue *q = vma->vm_private_data;
> @@ -265,6 +274,7 @@ static void uacce_vma_close(struct vm_area_struct *vma)
> }
>
> static const struct vm_operations_struct uacce_vm_ops = {
> + .fault = uacce_vma_fault,
> .close = uacce_vma_close,
> };
>
> @@ -585,6 +595,13 @@ void uacce_remove(struct uacce_device *uacce)
> cdev_device_del(uacce->cdev, &uacce->dev);
> xa_erase(&uacce_xa, uacce->dev_id);
> put_device(&uacce->dev);
> +
> + /*
> + * unmap remainning 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);
Should we unmap them at the first of 'uacce_remove', and before
'uacce_put_queue'?
Thanks,
Zaibo
.
> }
> EXPORT_SYMBOL_GPL(uacce_remove);
>
> diff --git a/include/linux/uacce.h b/include/linux/uacce.h
> index 904a461..0e215e6 100644
> --- a/include/linux/uacce.h
> +++ b/include/linux/uacce.h
> @@ -98,6 +98,7 @@ struct uacce_queue {
> * @priv: private pointer of the uacce
> * @mm_list: list head of uacce_mm->list
> * @mm_lock: lock for mm_list
> + * @inode: core vfs
> */
> struct uacce_device {
> const char *algs;
> @@ -113,6 +114,7 @@ struct uacce_device {
> void *priv;
> struct list_head mm_list;
> struct mutex mm_lock;
> + struct inode *inode;
> };
>
> /**