[PATCH] [media] s3c-camif: array underflow in __camif_subdev_try_format()

[Dan Carpenter <dan.carpenter@oracle.com>]

The while loop is a post op, "while (i-- >= 0)" so the last iteration
will read camif_mbus_formats[-1] and then the loop will exit with "i"
set to -2 and so we do: "mf->code = camif_mbus_formats[-2];".

I've changed it to a pre-op, I've added a check to ensure we found the
right format and I've removed the "mf->code = camif_mbus_formats[i];"
because that is a no-op anyway.

Fixes: babde1c243b2 ("[media] V4L: Add driver for S3C24XX/S3C64XX SoC series camera interface")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/drivers/media/platform/s3c-camif/camif-capture.c b/drivers/media/platform/s3c-camif/camif-capture.c
index 437395a61065..012f4b389c55 100644
--- a/drivers/media/platform/s3c-camif/camif-capture.c
+++ b/drivers/media/platform/s3c-camif/camif-capture.c
@@ -1261,11 +1261,11 @@ static void __camif_subdev_try_format(struct camif_dev *camif,
 	/* FIXME: constraints against codec or preview path ? */
 	pix_lim = &variant->vp_pix_limits[VP_CODEC];
 
-	while (i-- >= 0)
+	while (--i >= 0)
 		if (camif_mbus_formats[i] = mf->code)
 			break;
-
-	mf->code = camif_mbus_formats[i];
+	if (i < 0)
+		return;
 
 	if (pad = CAMIF_SD_PAD_SINK) {
 		v4l_bound_align_image(&mf->width, 8, CAMIF_MAX_PIX_WIDTH,