[PATCH v2] uio: Fix uio driver to refcount device

[PATCH v2] uio: Fix uio driver to refcount device

[Brian Russell]

Protect uio driver from crashing if its owner is hot unplugged while there
are open fds.

Signed-off-by: Brian Russell <brussell@brocade.com>
---
 drivers/uio/uio.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 6276f13..70ce015 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -434,9 +434,11 @@ static int uio_open(struct inode *inode, struct file *filep)
 		goto out;
 	}
 
+	get_device(idev);
+
 	if (!try_module_get(idev->owner)) {
 		ret = -ENODEV;
-		goto out;
+		goto err_module_get;
 	}
 
 	listener = kmalloc(sizeof(*listener), GFP_KERNEL);
@@ -462,6 +464,9 @@ err_infoopen:
 err_alloc_listener:
 	module_put(idev->owner);
 
+err_module_get:
+	put_device(idev);
+
 out:
 	return ret;
 }
@@ -485,6 +490,7 @@ static int uio_release(struct inode *inode, struct file *filep)
 
 	module_put(idev->owner);
 	kfree(listener);
+	put_device(idev);
 	return ret;
 }
 
-- 
2.1.4

Re: [PATCH v2] uio: Fix uio driver to refcount device

[Brian Russell]

Responding to myself ...

On 13/03/15 10:17, Brian Russell wrote:
> Protect uio driver from crashing if its owner is hot unplugged while there
> are open fds.
> 
> Signed-off-by: Brian Russell <brussell@brocade.com>
> ---
>  drivers/uio/uio.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index 6276f13..70ce015 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -434,9 +434,11 @@ static int uio_open(struct inode *inode, struct file *filep)
>  		goto out;
>  	}
>  
> +	get_device(idev);
> +

This is bogus, idev is uio_device *, not device *. Turns out this patch only masked the crash I was seeing, so please ignore. Updated version to follow ...

Thanks,

Brian

>  	if (!try_module_get(idev->owner)) {
>  		ret = -ENODEV;
> -		goto out;
> +		goto err_module_get;
>  	}
>  
>  	listener = kmalloc(sizeof(*listener), GFP_KERNEL);
> @@ -462,6 +464,9 @@ err_infoopen:
>  err_alloc_listener:
>  	module_put(idev->owner);
>  
> +err_module_get:
> +	put_device(idev);
> +
>  out:
>  	return ret;
>  }
> @@ -485,6 +490,7 @@ static int uio_release(struct inode *inode, struct file *filep)
>  
>  	module_put(idev->owner);
>  	kfree(listener);
> +	put_device(idev);
>  	return ret;
>  }
>  
>