Subject: CVE-2021-47105: ice: xsk: return xsk buffers back to pool when cleaning the ring

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

ice: xsk: return xsk buffers back to pool when cleaning the ring

Currently we only NULL the xdp_buff pointer in the internal SW ring but
we never give it back to the xsk buffer pool. This means that buffers
can be leaked out of the buff pool and never be used again.

Add missing xsk_buff_free() call to the routine that is supposed to
clean the entries that are left in the ring so that these buffers in the
umem can be used by other sockets.

Also, only go through the space that is actually left to be cleaned
instead of a whole ring.

The Linux kernel CVE team has assigned CVE-2021-47105 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 5.5 with commit 2d4238f55697 and fixed in 5.15.12 with commit ad6d20da2cfb
	Issue introduced in 5.5 with commit 2d4238f55697 and fixed in 5.16 with commit afe8a3ba85ec

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2021-47105
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/net/ethernet/intel/ice/ice_xsk.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/ad6d20da2cfbe14b7b1200d15f39e65988b0b9e8
	https://git.kernel.org/stable/c/afe8a3ba85ec2a6b6849367e25c06a2f8e0ddd05