Re: [PATCH 1/2] staging: media: tegra-video: fix wrong return type in tegra_get_format_fourcc_by_idx()

[Hans Verkuil <hverkuil+cisco@kernel.org>]

On 11/04/2026 23:10, Alexandru Hossu wrote:
> The function is declared to return u32, but returns -EINVAL on the error
> path. Due to implicit conversion, -EINVAL (-22) becomes 0xFFFFFFEA as u32,
> which is an invalid V4L2 pixel format value.
> 
> The caller tegra_channel_enum_format() assigns this garbage value directly
> to f->pixelformat and returns 0 (success) to userspace via VIDIOC_ENUM_FMT,
> giving applications a silently wrong format descriptor instead of an error.
> 
> Fix this by changing the return type to int and propagating the error
> correctly in the caller.
> 
> Signed-off-by: Alexandru Hossu <hossu.alexandru@gmail.com>

It's a duplicate of https://patchwork.linuxtv.org/project/linux-media/patch/20260412000245.26696-1-dennylin0707@gmail.com/

I prefer that version (after my suggested change) over this one.

Regards,

	Hans

> ---
>  drivers/staging/media/tegra-video/vi.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/media/tegra-video/vi.c b/drivers/staging/media/tegra-video/vi.c
> index 9c0b38585d63..afc7327ef318 100644
> --- a/drivers/staging/media/tegra-video/vi.c
> +++ b/drivers/staging/media/tegra-video/vi.c
> @@ -77,13 +77,13 @@ static int tegra_get_format_idx_by_code(struct tegra_vi *vi,
>  	return -1;
>  }
>  
> -static u32 tegra_get_format_fourcc_by_idx(struct tegra_vi *vi,
> +static int tegra_get_format_fourcc_by_idx(struct tegra_vi *vi,
>  					  unsigned int index)
>  {
>  	if (index >= vi->soc->nformats)
>  		return -EINVAL;
>  
> -	return vi->soc->video_formats[index].fourcc;
> +	return (int)vi->soc->video_formats[index].fourcc;
>  }
>  
>  static const struct tegra_video_format *
> @@ -395,6 +395,7 @@ static int tegra_channel_enum_format(struct file *file, void *fh,
>  	struct tegra_vi_channel *chan = video_drvdata(file);
>  	unsigned int index = 0, i;
>  	unsigned long *fmts_bitmap = chan->tpg_fmts_bitmap;
> +	int ret;
>  
>  	if (!IS_ENABLED(CONFIG_VIDEO_TEGRA_TPG))
>  		fmts_bitmap = chan->fmts_bitmap;
> @@ -405,7 +406,11 @@ static int tegra_channel_enum_format(struct file *file, void *fh,
>  	for (i = 0; i < f->index + 1; i++, index++)
>  		index = find_next_bit(fmts_bitmap, MAX_FORMAT_NUM, index);
>  
> -	f->pixelformat = tegra_get_format_fourcc_by_idx(chan->vi, index - 1);
> +	ret = tegra_get_format_fourcc_by_idx(chan->vi, index - 1);
> +	if (ret < 0)
> +		return ret;
> +
> +	f->pixelformat = ret;
>  
>  	return 0;
>  }