media: tegra-video: vi: fix invalid u32 return value in format lookup

commit d5b5005 upstream.

tegra_get_format_fourcc_by_idx() returns a u32 but uses -EINVAL to
signal an out-of-bounds index. This results in a large unsigned
value being returned, which may be interpreted as a valid fourcc.

Returning 0 is not a valid fourcc either. This condition should
never happen, so use WARN_ON_ONCE() to catch unexpected out-of-bounds
access and return a valid fallback format instead.

Suggested-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Fixes: 3d8a97e ("media: tegra-video: Add Tegra210 Video input driver")
Cc: stable@vger.kernel.org
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Hungyu Lin <dennylin0707@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Denny-Lin

drivers/staging/media/tegra-video/vi.c

@@ -80,8 +80,8 @@ static int tegra_get_format_idx_by_code(struct tegra_vi *vi,
 static u32 tegra_get_format_fourcc_by_idx(struct tegra_vi *vi,
 					  unsigned int index)
 {
-	if (index >= vi->soc->nformats)
-		return -EINVAL;
+	if (WARN_ON_ONCE(index >= vi->soc->nformats))
+		return vi->soc->video_formats[0].fourcc;
 
 	return vi->soc->video_formats[index].fourcc;
 }