linux-kernel - Re: [PATCH] udlfb: fix NULL pointer dereference in dlfb_usb

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Message-ID: <alpine.LRH.2.02.1811120923520.3272@file01.intranet.prod.int.rdu2.redhat.com>
Date:   Mon, 12 Nov 2018 09:24:35 -0500 (EST)
From:   Mikulas Patocka <mpatocka@...hat.com>
To:     Alexey Khoroshilov <khoroshilov@...ras.ru>
cc:     Bernie Thompson <bernie@...gable.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, ldv-project@...uxtesting.org
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 <khoroshilov@...ras.ru>
> Fixes: 68a958a915ca ("udlfb: handle unplug properly")

Reviewed-by: Mikulas Patocka <mpatocka@...hat.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
>