[media] media/vivid-osd: fix info leak in ioctl

commit eda98796 upstream.

The vivid_fb_ioctl() code fails to initialize the 16 _reserved bytes of
struct fb_vblank after the ->hcount member. Add an explicit
memset(0) before filling the structure to avoid the info leak.
Signed-off-by: Salva Peiró <speirofr@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Reference: CVE-2015-7884
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/media/platform/vivid/vivid-osd.c

@@ -85,6 +85,7 @@ static int vivid_fb_ioctl(struct fb_info *info, unsigned cmd, unsigned long arg)
 	case FBIOGET_VBLANK: {
 		struct fb_vblank vblank;
 
+		memset(&vblank, 0, sizeof(vblank));
 		vblank.flags = FB_VBLANK_HAVE_COUNT | FB_VBLANK_HAVE_VCOUNT |
 			FB_VBLANK_HAVE_VSYNC;
 		vblank.count = 0;