diff mbox series

[4/8] media: imx: Fail conversion if pixel format not supported

Message ID 20220204121514.2762676-5-alexander.stein@ew.tq-group.com (mailing list archive)
State Superseded, archived
Headers
Series imx7/imx8mm media / csi patches |

Commit Message

Alexander Stein Feb. 4, 2022, 12:15 p.m. UTC 
  From: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>

imx_media_find_mbus_format has NULL as a valid return value,
therefore the caller should take it into account.

Signed-off-by: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
---
 drivers/staging/media/imx/imx-media-utils.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Laurent Pinchart Feb. 5, 2022, 4:07 a.m. UTC | #1 
Hi Alexander and Dorota,

Thank you for the patch.

On Fri, Feb 04, 2022 at 01:15:10PM +0100, Alexander Stein wrote:
> From: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
> 
> imx_media_find_mbus_format has NULL as a valid return value,
> therefore the caller should take it into account.
> 
> Signed-off-by: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
> Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> ---
>  drivers/staging/media/imx/imx-media-utils.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/staging/media/imx/imx-media-utils.c b/drivers/staging/media/imx/imx-media-utils.c
> index 32aaa2e81bea..e0a256a08c3b 100644
> --- a/drivers/staging/media/imx/imx-media-utils.c
> +++ b/drivers/staging/media/imx/imx-media-utils.c
> @@ -544,6 +544,9 @@ static int imx56_media_mbus_fmt_to_pix_fmt(struct v4l2_pix_format *pix,
>  		cc = imx_media_find_mbus_format(code, PIXFMT_SEL_YUV);

The code passed to the function comes from the previous line:

	imx_media_enum_mbus_formats(&code, 0, PIXFMT_SEL_YUV);

As far as I can tell, this is guaranteed to return a code that will
result in imx_media_find_mbus_format() returning a non-NULL pointer.

>  	}
>  
> +	if (!cc)
> +		return -EINVAL;
> +
>  	/* Round up width for minimum burst size */
>  	width = round_up(mbus->width, 8);
>
Dorota Czaplejewicz Feb. 5, 2022, 7:51 a.m. UTC | #2 
Hi Laurent,

On Sat, 5 Feb 2022 06:07:37 +0200
Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote:

> Hi Alexander and Dorota,
> 
> Thank you for the patch.
> 
> On Fri, Feb 04, 2022 at 01:15:10PM +0100, Alexander Stein wrote:
> > From: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
> > 
> > imx_media_find_mbus_format has NULL as a valid return value,
> > therefore the caller should take it into account.
> > 
> > Signed-off-by: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
> > Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> > ---
> >  drivers/staging/media/imx/imx-media-utils.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/staging/media/imx/imx-media-utils.c b/drivers/staging/media/imx/imx-media-utils.c
> > index 32aaa2e81bea..e0a256a08c3b 100644
> > --- a/drivers/staging/media/imx/imx-media-utils.c
> > +++ b/drivers/staging/media/imx/imx-media-utils.c
> > @@ -544,6 +544,9 @@ static int imx56_media_mbus_fmt_to_pix_fmt(struct v4l2_pix_format *pix,
> >  		cc = imx_media_find_mbus_format(code, PIXFMT_SEL_YUV);  
> 
> The code passed to the function comes from the previous line:
> 
> 	imx_media_enum_mbus_formats(&code, 0, PIXFMT_SEL_YUV);
> 
> As far as I can tell, this is guaranteed to return a code that will
> result in imx_media_find_mbus_format() returning a non-NULL pointer.
> 
While I am not well-versed in the implicit code style of the kernel, I decided to leave it in because it makes the code more locally legible. With a check here, even a non-functional one, there's no need to understand the internals of `imx_media_find_mbus_format` that are only implicit. That makes the code less surprising when interested only in the outer function.

The other advantage of a check is becoming robust against future changes to `imx_media_find_mbus_format` itself.

I don't have a strong preference about keeping or leaving this patch, but if this check was there in the first place, I wouldn't have spent time trying to figure out whether there's a bug here.

Cheers,
Dorota

> >  	}
> >  
> > +	if (!cc)
> > +		return -EINVAL;
> > +
> >  	/* Round up width for minimum burst size */
> >  	width = round_up(mbus->width, 8);
> >    
>
Alexander Stein Feb. 7, 2022, 9:52 a.m. UTC | #3 
Hi Laurent and Dorota,

Am Samstag, 5. Februar 2022, 08:51:51 CET schrieb Dorota Czaplejewicz:
> * PGP Signed by an unknown key
> 
> Hi Laurent,
> 
> On Sat, 5 Feb 2022 06:07:37 +0200
> 
> Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote:
> > Hi Alexander and Dorota,
> > 
> > Thank you for the patch.
> > 
> > On Fri, Feb 04, 2022 at 01:15:10PM +0100, Alexander Stein wrote:
> > > From: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
> > > 
> > > imx_media_find_mbus_format has NULL as a valid return value,
> > > therefore the caller should take it into account.
> > > 
> > > Signed-off-by: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
> > > Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> > > ---
> > > 
> > >  drivers/staging/media/imx/imx-media-utils.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/drivers/staging/media/imx/imx-media-utils.c
> > > b/drivers/staging/media/imx/imx-media-utils.c index
> > > 32aaa2e81bea..e0a256a08c3b 100644
> > > --- a/drivers/staging/media/imx/imx-media-utils.c
> > > +++ b/drivers/staging/media/imx/imx-media-utils.c
> > > @@ -544,6 +544,9 @@ static int imx56_media_mbus_fmt_to_pix_fmt(struct
> > > v4l2_pix_format *pix,> > 
> > >  		cc = imx_media_find_mbus_format(code, PIXFMT_SEL_YUV);
> > 
> > The code passed to the function comes from the previous line:
> > 	imx_media_enum_mbus_formats(&code, 0, PIXFMT_SEL_YUV);
> > 
> > As far as I can tell, this is guaranteed to return a code that will
> > result in imx_media_find_mbus_format() returning a non-NULL pointer.
> 
> While I am not well-versed in the implicit code style of the kernel, I
> decided to leave it in because it makes the code more locally legible. With
> a check here, even a non-functional one, there's no need to understand the
> internals of `imx_media_find_mbus_format` that are only implicit. That
> makes the code less surprising when interested only in the outer function.
> 
> The other advantage of a check is becoming robust against future changes to
> `imx_media_find_mbus_format` itself.
> 
> I don't have a strong preference about keeping or leaving this patch, but if
> this check was there in the first place, I wouldn't have spent time trying
> to figure out whether there's a bug here.

Laurent, thanks for your feedback.
I'm on Dorota's side here. While you are right that the code from 
  imx_media_enum_mbus_formats(&code, 0, PIXFMT_SEL_YUV);
is guaranteed to return something. I don't lnek this implicit assumption over 
2 function calls. Better be safe than sorry. For that reason code should be 
initialized as well. Will create a patch for that.

Regards,
Alexander
Laurent Pinchart Feb. 8, 2022, 1:14 a.m. UTC | #4 
Hello,

On Mon, Feb 07, 2022 at 10:52:00AM +0100, Alexander Stein wrote:
> Am Samstag, 5. Februar 2022, 08:51:51 CET schrieb Dorota Czaplejewicz:
> > On Sat, 5 Feb 2022 06:07:37 +0200 Laurent Pinchart wrote:
> > > On Fri, Feb 04, 2022 at 01:15:10PM +0100, Alexander Stein wrote:
> > > > From: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
> > > > 
> > > > imx_media_find_mbus_format has NULL as a valid return value,
> > > > therefore the caller should take it into account.
> > > > 
> > > > Signed-off-by: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
> > > > Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> > > > ---
> > > > 
> > > >  drivers/staging/media/imx/imx-media-utils.c | 3 +++
> > > >  1 file changed, 3 insertions(+)
> > > > 
> > > > diff --git a/drivers/staging/media/imx/imx-media-utils.c
> > > > b/drivers/staging/media/imx/imx-media-utils.c index
> > > > 32aaa2e81bea..e0a256a08c3b 100644
> > > > --- a/drivers/staging/media/imx/imx-media-utils.c
> > > > +++ b/drivers/staging/media/imx/imx-media-utils.c
> > > > @@ -544,6 +544,9 @@ static int imx56_media_mbus_fmt_to_pix_fmt(struct
> > > > v4l2_pix_format *pix,> > 
> > > >  		cc = imx_media_find_mbus_format(code, PIXFMT_SEL_YUV);
> > > 
> > > The code passed to the function comes from the previous line:
> > > 	imx_media_enum_mbus_formats(&code, 0, PIXFMT_SEL_YUV);
> > > 
> > > As far as I can tell, this is guaranteed to return a code that will
> > > result in imx_media_find_mbus_format() returning a non-NULL pointer.
> > 
> > While I am not well-versed in the implicit code style of the kernel, I
> > decided to leave it in because it makes the code more locally legible. With
> > a check here, even a non-functional one, there's no need to understand the
> > internals of `imx_media_find_mbus_format` that are only implicit. That
> > makes the code less surprising when interested only in the outer function.
> > 
> > The other advantage of a check is becoming robust against future changes to
> > `imx_media_find_mbus_format` itself.
> > 
> > I don't have a strong preference about keeping or leaving this patch, but if
> > this check was there in the first place, I wouldn't have spent time trying
> > to figure out whether there's a bug here.
> 
> Laurent, thanks for your feedback.
> I'm on Dorota's side here. While you are right that the code from 
>   imx_media_enum_mbus_formats(&code, 0, PIXFMT_SEL_YUV);
> is guaranteed to return something. I don't lnek this implicit assumption over 
> 2 function calls. Better be safe than sorry. For that reason code should be 
> initialized as well. Will create a patch for that.

I'm fine with hardening the code even if the issue can't occur at the
moment.
diff mbox series

Patch

diff --git a/drivers/staging/media/imx/imx-media-utils.c b/drivers/staging/media/imx/imx-media-utils.c
index 32aaa2e81bea..e0a256a08c3b 100644
--- a/drivers/staging/media/imx/imx-media-utils.c
+++ b/drivers/staging/media/imx/imx-media-utils.c
@@ -544,6 +544,9 @@  static int imx56_media_mbus_fmt_to_pix_fmt(struct v4l2_pix_format *pix,
 		cc = imx_media_find_mbus_format(code, PIXFMT_SEL_YUV);
 	}
 
+	if (!cc)
+		return -EINVAL;
+
 	/* Round up width for minimum burst size */
 	width = round_up(mbus->width, 8);