media: stm32-dcmi: fix crash when subdev do not expose any formats

Do not access sd_formats[] if num_of_sd_formats is zero, ie
subdev sensor didn't expose any formats.

Signed-off-by: Hugues Fruchet <hugues.fruchet@st.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/stm32/stm32-dcmi.c

@@ -831,6 +831,9 @@ static int dcmi_try_fmt(struct stm32_dcmi *dcmi, struct v4l2_format *f,
 
 	sd_fmt = find_format_by_fourcc(dcmi, pix->pixelformat);
 	if (!sd_fmt) {
+		if (!dcmi->num_of_sd_formats)
+			return -ENODATA;
+
 		sd_fmt = dcmi->sd_formats[dcmi->num_of_sd_formats - 1];
 		pix->pixelformat = sd_fmt->fourcc;
 	}
@@ -1009,6 +1012,9 @@ static int dcmi_set_sensor_format(struct stm32_dcmi *dcmi,
 
 	sd_fmt = find_format_by_fourcc(dcmi, pix->pixelformat);
 	if (!sd_fmt) {
+		if (!dcmi->num_of_sd_formats)
+			return -ENODATA;
+
 		sd_fmt = dcmi->sd_formats[dcmi->num_of_sd_formats - 1];
 		pix->pixelformat = sd_fmt->fourcc;
 	}