Describe CVE-2021-47523.
What is CVE-2021-47523?
In the Linux kernel, the following vulnerability has been resolved:

IB/hfi1: Fix leak of rcvhdrtail_dummy_kvaddr

This buffer is currently allocated in hfi1_init():

	if (reinit)
		ret = init_after_reset(dd);
	else
		ret = loadtime_init(dd);
	if (ret)
		goto done;

	/* allocate dummy tail memory for all receive contexts */
	dd->rcvhdrtail_dummy_kvaddr = dma_alloc_coherent(&dd->pcidev->dev,
							 sizeof(u64),
							 &dd->rcvhdrtail_dummy_dma,
							 GFP_KERNEL);

	if (!dd->rcvhdrtail_dummy_kvaddr) {
		dd_dev_err(dd, "cannot allocate dummy tail memory\n");
		ret = -ENOMEM;
		goto done;
	}

The reinit triggered path will overwrite the old allocation and leak it.

Fix by moving the allocation to hfi1_alloc_devdata() and the deallocation
to hfi1_free_devdata()..