linux-kernel - [PATCH 4.19 023/276] udlfb: fix some inconsistent NULL checking

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Date:   Wed, 29 May 2019 20:03:01 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Bernie Thompson <bernie@...gable.com>,
        Mikulas Patocka <mpatocka@...hat.com>,
        Alexey Khoroshilov <khoroshilov@...ras.ru>,
        Colin Ian King <colin.king@...onical.com>,
        Wen Yang <wen.yang99@....com.cn>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: [PATCH 4.19 023/276] udlfb: fix some inconsistent NULL checking

From: Dan Carpenter <dan.carpenter@...cle.com>

commit c143a559b073aeea688b9bb7c5b46f3cf322d569 upstream.

In the current kernel, then kzalloc() can't fail for small allocations,
but if it did fail then we would have a NULL dereference in the error
handling.  Also in dlfb_usb_disconnect() if "info" were NULL then it
would cause an Oops inside the unregister_framebuffer() function but it
can't be NULL so let's remove that check.

Fixes: 68a958a915ca ("udlfb: handle unplug properly")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Cc: Bernie Thompson <bernie@...gable.com>
Cc: Mikulas Patocka <mpatocka@...hat.com>
Cc: Alexey Khoroshilov <khoroshilov@...ras.ru>
Cc: Colin Ian King <colin.king@...onical.com>
Cc: Wen Yang <wen.yang99@....com.cn>
[b.zolnierkie: added "Fixes:" tag]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/video/fbdev/udlfb.c |   14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

--- a/drivers/video/fbdev/udlfb.c
+++ b/drivers/video/fbdev/udlfb.c
@@ -1659,7 +1659,7 @@ static int dlfb_usb_probe(struct usb_int
 	dlfb = kzalloc(sizeof(*dlfb), GFP_KERNEL);
 	if (!dlfb) {
 		dev_err(&intf->dev, "%s: failed to allocate dlfb\n", __func__);
-		goto error;
+		return -ENOMEM;
 	}
 
 	INIT_LIST_HEAD(&dlfb->deferred_free);
@@ -1769,7 +1769,7 @@ static int dlfb_usb_probe(struct usb_int
 error:
 	if (dlfb->info) {
 		dlfb_ops_destroy(dlfb->info);
-	} else if (dlfb) {
+	} else {
 		usb_put_dev(dlfb->udev);
 		kfree(dlfb);
 	}
@@ -1796,12 +1796,10 @@ static void dlfb_usb_disconnect(struct u
 	/* this function will wait for all in-flight urbs to complete */
 	dlfb_free_urb_list(dlfb);
 
-	if (info) {
-		/* remove udlfb's sysfs interfaces */
-		for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
-			device_remove_file(info->dev, &fb_device_attrs[i]);
-		device_remove_bin_file(info->dev, &edid_attr);
-	}
+	/* remove udlfb's sysfs interfaces */
+	for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
+		device_remove_file(info->dev, &fb_device_attrs[i]);
+	device_remove_bin_file(info->dev, &edid_attr);
 
 	unregister_framebuffer(info);
 }