linux-kernel - Re: [PATCH 4.19 047/125] media: davinci: vpif

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Message-ID: <20200901183912.GA5295@duo.ucw.cz>
Date:   Tue, 1 Sep 2020 20:42:58 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Evgeny Novikov <novikov@...ras.ru>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.19 047/125] media: davinci: vpif_capture: fix potential
 double free

Hi!

> [ Upstream commit 602649eadaa0c977e362e641f51ec306bc1d365d ]
> 
> In case of errors vpif_probe_complete() releases memory for vpif_obj.sd
> and unregisters the V4L2 device. But then this is done again by
> vpif_probe() itself. The patch removes the cleaning from
> vpif_probe_complete().

> Signed-off-by: Evgeny Novikov <novikov@...ras.ru>
> Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.nl>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  drivers/media/platform/davinci/vpif_capture.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/media/platform/davinci/vpif_capture.c b/drivers/media/platform/davinci/vpif_capture.c
> index a96f53ce80886..cf1d11e6dd8c4 100644
> --- a/drivers/media/platform/davinci/vpif_capture.c
> +++ b/drivers/media/platform/davinci/vpif_capture.c
> @@ -1489,8 +1489,6 @@ probe_out:
>  		/* Unregister video device */
>  		video_unregister_device(&ch->video_dev);
>  	}
> -	kfree(vpif_obj.sd);
> -	v4l2_device_unregister(&vpif_obj.v4l2_dev);
>  
>  	return err;
>  }

This one is wrong. Unlike mainline, 4.19 does check return value of
vpif_probe_complete(), and thus it will lead to memory leak in 4.19.

Furthermore, I believe mainline still has a problems after this
patch. There is sync and async path where vpif_probe_complete(), and
while this fixes the sync path in mainline, I believe it will cause
memory leak on the async path.

Best regards,
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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