sound: usb: usx2y: is it a null pointer deference in function usX2Y_rate_set?

[亿一]

Hi, all:
    when reviewing function usX2Y_rate_set, here may exist a NULL
pointer deference if kmalloc_array failed or usb_alloc_urb failed,
in cleanup,  we should judge whether us->urb[i] is NULL first.
static int usX2Y_rate_set(struct usX2Ydev *usX2Y, int rate)
{
    us = kzalloc(sizeof(*us) + sizeof(struct urb*) *
NOOF_SETRATE_URBS, GFP_KERNEL);
    if (NULL == us) {
        err = -ENOMEM;
        goto cleanup;
    }
    usbdata = kmalloc_array(NOOF_SETRATE_URBS, sizeof(int),
                GFP_KERNEL);
    if (NULL == usbdata) {
        err = -ENOMEM;
        goto cleanup;
    }
    for (i = 0; i < NOOF_SETRATE_URBS; ++i) {
        if (NULL == (us->urb[i] = usb_alloc_urb(0, GFP_KERNEL))) {
            err = -ENOMEM;
            goto cleanup;
        }
        ...
    }
    ...
cleanup:
    if (us) {
        us->submitted = 2*NOOF_SETRATE_URBS;
        for (i = 0; i < NOOF_SETRATE_URBS; ++i) {
            struct urb *urb = us->urb[i];
            if (urb->status) {
                if (!err)
                    err = -ENODEV;
                usb_kill_urb(urb);
            }
            usb_free_urb(urb);