media: v4l2-compat-ioctl32.c: zero buffer passed to v4l2_compat_get_array_args()

The v4l2_compat_get_array_args() function can leave uninitialized memory in the
buffer it is passed. So zero it before copying array elements from userspace
into the buffer.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reported-by: syzbot+ff18193ff05f3f87f226@syzkaller.appspotmail.com
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/v4l2-core/v4l2-compat-ioctl32.c

@@ -1040,6 +1040,8 @@ int v4l2_compat_get_array_args(struct file *file, void *mbuf,
 {
 	int err = 0;
 
+	memset(mbuf, 0, array_size);
+
 	switch (cmd) {
 	case VIDIOC_G_FMT32:
 	case VIDIOC_S_FMT32: