Subject: CVE-2021-46916: ixgbe: Fix NULL pointer dereference in ethtool loopback test

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

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

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

ixgbe: Fix NULL pointer dereference in ethtool loopback test

The ixgbe driver currently generates a NULL pointer dereference when
performing the ethtool loopback test. This is due to the fact that there
isn't a q_vector associated with the test ring when it is setup as
interrupts are not normally added to the test rings.

To address this I have added code that will check for a q_vector before
returning a napi_id value. If a q_vector is not present it will return a
value of 0.

The Linux kernel CVE team has assigned CVE-2021-46916 to this issue.

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

	Issue introduced in 5.11 with commit b02e5a0ebb17 and fixed in 5.11.16 with commit 758d19098df4
	Issue introduced in 5.11 with commit b02e5a0ebb17 and fixed in 5.12 with commit 31166efb1cee

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-2021-46916
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/ixgbe/ixgbe_main.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/758d19098df4b0bbca9f40d6ae6c82c9c18b9bba
	https://git.kernel.org/stable/c/31166efb1cee348eb6314e9c0095d84cbeb66b9d