[media] V4L2: ov7670: fix a wrong index, potentially Oopsing the kernel from user-space

Commit 75e2bdad8901a0b599e01a96229be922eef1e488 "ov7670: allow
configuration of image size, clock speed, and I/O method" uses a wrong
index to iterate an array. Apart from being wrong, it also uses an
unchecked value from user-space, which can cause access to unmapped
memory in the kernel, triggered by a normal desktop user with rights to
use V4L2 devices.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/i2c/ov7670.c

@@ -1109,7 +1109,7 @@ static int ov7670_enum_framesizes(struct v4l2_subdev *sd,
 	 * windows that fall outside that.
 	 */
 	for (i = 0; i < n_win_sizes; i++) {
-		struct ov7670_win_size *win = &info->devtype->win_sizes[index];
+		struct ov7670_win_size *win = &info->devtype->win_sizes[i];
 		if (info->min_width && win->width < info->min_width)
 			continue;
 		if (info->min_height && win->height < info->min_height)