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

commit cfece585 upstream.

Commit 75e2bdad "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>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
[bwh: Backported to 3.2:
 - Adjust filename
 - win_sizes array is static, not per-device]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/media/video/ov7670.c

@@ -937,7 +937,7 @@ 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 = &ov7670_win_sizes[index];
+		struct ov7670_win_size *win = &ov7670_win_sizes[i];
 		if (info->min_width && win->width < info->min_width)
 			continue;
 		if (info->min_height && win->height < info->min_height)