Re: [PATCH v2] media: verisilicon: Fix crash when probing encoder

From: Michael Tretter <m.tretter@pengutronix.de>
To: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Cc: ezequiel@vanguardiasur.com.ar, p.zabel@pengutronix.de,
	mchehab@kernel.org, m.szyprowski@samsung.com,
	linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org,
	linux-kernel@vger.kernel.org, kernel@collabora.com,
	kernel@pengutronix.de, nicolas.dufresne@collabora.com,
	didi.debian@cknow.org, hverkuil-cisco@xs4all.nl
Subject: Re: [PATCH v2] media: verisilicon: Fix crash when probing encoder
Date: Thu, 1 Jun 2023 15:27:49 +0200	[thread overview]
Message-ID: <20230601132749.GA31313@pengutronix.de> (raw)
In-Reply-To: <20230413104756.356695-1-benjamin.gaignard@collabora.com>

Hi Benjamin,

On Thu, 13 Apr 2023 12:47:56 +0200, Benjamin Gaignard wrote:
> ctx->vpu_dst_fmt is no more initialized before calling hantro_try_fmt()
> so assigne it to vpu_fmt led to crash the kernel.
> Like for decoder case use 'fmt' as format for encoder and clean up
> the code.
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Fixes: db6f68b51e5c ("media: verisilicon: Do not set context src/dst formats in reset functions")
> ---
> version 2:
> - Remove useless vpu_fmt.
> 
>  drivers/media/platform/verisilicon/hantro_v4l2.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/media/platform/verisilicon/hantro_v4l2.c b/drivers/media/platform/verisilicon/hantro_v4l2.c
> index 8f1414085f47..d71f79471396 100644
> --- a/drivers/media/platform/verisilicon/hantro_v4l2.c
> +++ b/drivers/media/platform/verisilicon/hantro_v4l2.c
> @@ -275,7 +275,7 @@ static int hantro_try_fmt(const struct hantro_ctx *ctx,
>  			  struct v4l2_pix_format_mplane *pix_mp,
>  			  enum v4l2_buf_type type)
>  {
> -	const struct hantro_fmt *fmt, *vpu_fmt;
> +	const struct hantro_fmt *fmt;
>  	bool capture = V4L2_TYPE_IS_CAPTURE(type);
>  	bool coded;
>  
> @@ -295,11 +295,7 @@ static int hantro_try_fmt(const struct hantro_ctx *ctx,
>  
>  	if (coded) {
>  		pix_mp->num_planes = 1;
> -		vpu_fmt = fmt;
> -	} else if (ctx->is_encoder) {
> -		vpu_fmt = ctx->vpu_dst_fmt;
> -	} else {
> -		vpu_fmt = fmt;
> +	} else if (!ctx->is_encoder) {
>  		/*
>  		 * Width/height on the CAPTURE end of a decoder are ignored and
>  		 * replaced by the OUTPUT ones.
> @@ -311,7 +307,7 @@ static int hantro_try_fmt(const struct hantro_ctx *ctx,
>  	pix_mp->field = V4L2_FIELD_NONE;
>  
>  	v4l2_apply_frmsize_constraints(&pix_mp->width, &pix_mp->height,
> -				       &vpu_fmt->frmsize);
> +				       &fmt->frmsize);

This causes a regression on the OUTPUT device of the encoder. fmt->frmsize is
only valid for coded ("bitstream") formats, but fmt on the OUTPUT of an
encoder will be a raw format. This results in width and height to be clamped
to 0.

I think the correct fix would be to apply the frmsize constraints of the
currently configured coded format, but as ctx->vpu_dst_fmt is not initialized
before calling this code, I don't know how to get the coded format.

Michael

>  
>  	if (!coded) {
>  		/* Fill remaining fields */
> -- 
> 2.34.1
> 