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Message-ID: <2dfd7785da904e9b518a0e7579d4db79a0b19276.camel@pengutronix.de>
Subject: Re: [PATCH v5 08/10] media: Quit parsing stream if doesn't start
 with SOI
From:   Philipp Zabel <p.zabel@pengutronix.de>
To:     "Mirela Rabulea (OSS)" <mirela.rabulea@oss.nxp.com>,
        mchehab@kernel.org, hverkuil-cisco@xs4all.nl, shawnguo@kernel.org,
        robh+dt@kernel.org
Cc:     paul.kocialkowski@bootlin.com, linux-media@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-imx@nxp.com,
        s.hauer@pengutronix.de, aisheng.dong@nxp.com,
        daniel.baluta@nxp.com, robert.chiras@nxp.com,
        laurentiu.palcu@nxp.com, mark.rutland@arm.com,
        devicetree@vger.kernel.org, ezequiel@collabora.com,
        laurent.pinchart+renesas@ideasonboard.com,
        niklas.soderlund+renesas@ragnatech.se,
        dafna.hirschfeld@collabora.com,
        Mirela Rabulea <mirela.rabulea@nxp.com>
Date:   Wed, 02 Dec 2020 16:18:44 +0100
In-Reply-To: <20201112030557.8540-9-mirela.rabulea@oss.nxp.com>
References: <20201112030557.8540-1-mirela.rabulea@oss.nxp.com>
         <20201112030557.8540-9-mirela.rabulea@oss.nxp.com>
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On Thu, 2020-11-12 at 05:05 +0200, Mirela Rabulea (OSS) wrote:
> From: Mirela Rabulea <mirela.rabulea@nxp.com>
> 
> In the case we get an invalid stream, such as from v4l2-compliance
> streaming test, jpeg_next_marker will end up parsing the entire
> stream. The standard describes the high level syntax of a jpeg
> as starting with SOI, ending with EOI, so return error if the very
> first 2 bytes are not SOI.
> 
> Signed-off-by: Mirela Rabulea <mirela.rabulea@nxp.com>
> ---
>  drivers/media/v4l2-core/v4l2-jpeg.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-jpeg.c b/drivers/media/v4l2-core/v4l2-jpeg.c
> index 3181ce544f79..d77e04083d57 100644
> --- a/drivers/media/v4l2-core/v4l2-jpeg.c
> +++ b/drivers/media/v4l2-core/v4l2-jpeg.c
> @@ -499,11 +499,8 @@ int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out)
>  	out->num_dht = 0;
>  	out->num_dqt = 0;
>  
> -	/* the first marker must be SOI */
> -	marker = jpeg_next_marker(&stream);
> -	if (marker < 0)
> -		return marker;
> -	if (marker != SOI)
> +	/* the first bytes must be SOI, B.2.1 High-level syntax */
> +	if (jpeg_get_word_be(&stream) != SOI)
>  		return -EINVAL;
>  
>  	/* init value to signal if this marker is not present */

Yes, shorter, potentially faster code, and it adheres to the
specification more strictly.

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>

regards
Philipp