2018-11-09 20:26:17

by Alexey Khoroshilov

Subject: [PATCH] udlfb: fix NULL pointer dereference in dlfb_usb_probe()

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 <[email protected]>
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

2018-11-12 14:25:36

by Mikulas Patocka

Subject: Re: [PATCH] udlfb: fix NULL pointer dereference in dlfb_usb_probe()

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 <[email protected]>
> Fixes: 68a958a915ca ("udlfb: handle unplug properly")

Reviewed-by: Mikulas Patocka <[email protected]>

> ---
> 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
>