# \[PATCH\] udlfb: fix NULL pointer dereference in dlfb\_usb\_probe()

- Subsystems: DISPLAYLINK USB 2.0 FRAMEBUFFER DRIVER (UDLFB), FRAMEBUFFER LAYER, THE REST
- Maintainers: Bernie Thompson, Helge Deller, Linus Torvalds
- List: linux-fbdev
- 2 messages, 2 authors
- Page: https://ratatoskr.run/linux-fbdev/2018/11/5429113/t

## \[PATCH\] udlfb: fix NULL pointer dereference in dlfb\_usb\_probe()

- From: Alexey Khoroshilov \<hidden\>
- Date: 2018-11-09 20:25:24 
- Message: https://ratatoskr.run/linux-fbdev/2018/11/5429113.md

```text
If memory allocation for dlfb fails, error handling code
unconditionally dereference NULL pointer.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <redacted>
Fixes: 68a958a915ca ("udlfb: handle unplug properly")
---
 drivers/video/fbdev/udlfb.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/video/fbdev/udlfb.c b/drivers/video/fbdev/udlfb.c
index 070026a7e55a..9643fe7c8349 100644
--- a/drivers/video/fbdev/udlfb.c
+++ b/drivers/video/fbdev/udlfb.c
@@ -1590,7 +1590,7 @@ static int dlfb_usb_probe(struct usb_interface *intf,
 	int i;
 	const struct device_attribute *attr;
 	struct dlfb_data *dlfb;
-	struct fb_info *info;
+	struct fb_info *info = NULL;
 	int retval = -ENOMEM;
 	struct usb_device *usbdev = interface_to_usbdev(intf);
 
@@ -1701,8 +1701,8 @@ static int dlfb_usb_probe(struct usb_interface *intf,
 	return 0;
 
 error:
-	if (dlfb->info) {
-		dlfb_ops_destroy(dlfb->info);
+	if (info) {
+		dlfb_ops_destroy(info);
 	} else if (dlfb) {
 		usb_put_dev(dlfb->udev);
 		kfree(dlfb);
-- 
2.7.4
```

## Re: \[PATCH\] udlfb: fix NULL pointer dereference in dlfb\_usb\_probe()

- From: Mikulas Patocka \<mpatocka@redhat.com\>
- Date: 2018-11-12 14:24:40 
- Message: https://ratatoskr.run/linux-fbdev/2018/11/5432022.md

```text


On Fri, 9 Nov 2018, Alexey Khoroshilov wrote:

> If memory allocation for dlfb fails, error handling code
> unconditionally dereference NULL pointer.
> 
> Found by Linux Driver Verification project (linuxtesting.org).
> 
> Signed-off-by: Alexey Khoroshilov <redacted>
> Fixes: 68a958a915ca ("udlfb: handle unplug properly")

Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>

> ---
>  drivers/video/fbdev/udlfb.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/video/fbdev/udlfb.c b/drivers/video/fbdev/udlfb.c
> index 070026a7e55a..9643fe7c8349 100644
> --- a/drivers/video/fbdev/udlfb.c
> +++ b/drivers/video/fbdev/udlfb.c
> @@ -1590,7 +1590,7 @@ static int dlfb_usb_probe(struct usb_interface *intf,
>  	int i;
>  	const struct device_attribute *attr;
>  	struct dlfb_data *dlfb;
> -	struct fb_info *info;
> +	struct fb_info *info = NULL;
>  	int retval = -ENOMEM;
>  	struct usb_device *usbdev = interface_to_usbdev(intf);
>  
> @@ -1701,8 +1701,8 @@ static int dlfb_usb_probe(struct usb_interface *intf,
>  	return 0;
>  
>  error:
> -	if (dlfb->info) {
> -		dlfb_ops_destroy(dlfb->info);
> +	if (info) {
> +		dlfb_ops_destroy(info);
>  	} else if (dlfb) {
>  		usb_put_dev(dlfb->udev);
>  		kfree(dlfb);
> -- 
> 2.7.4
> 
```