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

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Date:   Mon, 3 Dec 2018 14:21:25 +0800
From:   Wen Yang <wen.yang99@....com.cn>
To:     Bernie Thompson <bernie@...gable.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Cc:     linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, zhong.weidong@....com.cn,
        Wen Yang <wen.yang99@....com.cn>
Subject: [PATCH] udlfb: fix potential NULL pointer dereference in dlfb_usb_probe

This patch fixes a possible null pointer dereference in
dlfb_usb_probe, detected by the semantic patch deref_null.cocci,
with the following warning:

drivers/video/fbdev/udlfb.c:1704:11-15: ERROR: dlfb is NULL but dereferenced.

The following code has potential null pointer references:
1597         /* usb initialization */
1598         dlfb = kzalloc(sizeof(*dlfb), GFP_KERNEL);
1599         if (!dlfb) {
...
1601             goto error;
1602         }
...
1703 error:
1704         if (dlfb->info) {
1705                 dlfb_ops_destroy(dlfb->info);
1706         } else if (dlfb) {
1707                 usb_put_dev(dlfb->udev);
1708                 kfree(dlfb);
1709         }

Signed-off-by: Wen Yang <wen.yang99@....com.cn>
CC: Bernie Thompson <bernie@...gable.com>
CC: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
CC: linux-fbdev@...r.kernel.org
CC: dri-devel@...ts.freedesktop.org
CC: linux-kernel@...r.kernel.org
---
 drivers/video/fbdev/udlfb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/udlfb.c b/drivers/video/fbdev/udlfb.c
index 070026a7e55a..df37cfaa2362 100644
--- a/drivers/video/fbdev/udlfb.c
+++ b/drivers/video/fbdev/udlfb.c
@@ -1701,7 +1701,7 @@ static int dlfb_usb_probe(struct usb_interface *intf,
 	return 0;
 
 error:
-	if (dlfb->info) {
+	if (dlfb && dlfb->info) {
 		dlfb_ops_destroy(dlfb->info);
 	} else if (dlfb) {
 		usb_put_dev(dlfb->udev);
-- 
2.19.1