linux-kernel - Re: [PATCH] radio-si470x.c: check-after-use

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Message-Id: <200801292137.18035.tobias.lorenz@gmx.net>
Date:	Tue, 29 Jan 2008 21:37:17 +0100
From:	Tobias Lorenz <tobias.lorenz@....net>
To:	Oliver Neukum <oliver@...kum.org>
Cc:	Mauro Carvalho Chehab <mchehab@...radead.org>,
	Adrian Bunk <bunk@...nel.org>, video4linux-list@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] radio-si470x.c: check-after-use

Hi,

> > > Either "radio" can be NULL and this case has to be properly handled or 
> > > the NULL check is not required.
> > 
> > These two lines should indeed better be inside the if statement. The patch for this is below.
> 
> No, in disconnect intfdata must be valid. Any check for NULL is wrong
> there.

Why hadn't anybody told me that earlier? :-)
I removed the complete check for radio==NULL.
See the patch below.

Thanks,
  Toby


Signed-off-by: Tobias Lorenz <tobias.lorenz@....net>
--- linux-2.6.23/drivers/media/radio/radio-si470x.c     2008-01-23 00:01:07.000000000 +0100
+++ linux-2.6.23.new/drivers/media/radio/radio-si470x.c 2008-01-27 15:31:42.000000000 +0100
@@ -1441,13 +1441,11 @@ static void si470x_usb_driver_disconnect
        struct si470x_device *radio = usb_get_intfdata(intf);

        usb_set_intfdata(intf, NULL);
-       if (radio) {
-               del_timer_sync(&radio->timer);
-               flush_scheduled_work();
-               video_unregister_device(radio->videodev);
-               kfree(radio->buffer);
-               kfree(radio);
-       }
+       del_timer_sync(&radio->timer);
+       flush_scheduled_work();
+       video_unregister_device(radio->videodev);
+       kfree(radio->buffer);
+       kfree(radio);
 }
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