media: vivid: free bitmap_cap when updating std/timings/etc.

BugLink: https://bugs.launchpad.net/bugs/1811647

commit 560ccb75 upstream.

When vivid_update_format_cap() is called it should free any overlay
bitmap since the compose size will change.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reported-by: syzbot+0cc8e3cc63ca373722c6@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>      # for v3.18 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/media/platform/vivid/vivid-vid-cap.c

@@ -461,6 +461,8 @@ void vivid_update_format_cap(struct vivid_dev *dev, bool keep_controls)
 		tpg_s_rgb_range(&dev->tpg, v4l2_ctrl_g_ctrl(dev->rgb_range_cap));
 		break;
 	}
+	vfree(dev->bitmap_cap);
+	dev->bitmap_cap = NULL;
 	vivid_update_quality(dev);
 	tpg_reset_source(&dev->tpg, dev->src_rect.width, dev->src_rect.height, dev->field_cap);
 	dev->crop_cap = dev->src_rect;