Subject: CVE-2021-47101: asix: fix uninit-value in asix_mdio_read()

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

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

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

asix: fix uninit-value in asix_mdio_read()

asix_read_cmd() may read less than sizeof(smsr) bytes and in this case
smsr will be uninitialized.

Fail log:
BUG: KMSAN: uninit-value in asix_check_host_enable drivers/net/usb/asix_common.c:82 [inline]
BUG: KMSAN: uninit-value in asix_check_host_enable drivers/net/usb/asix_common.c:82 [inline] drivers/net/usb/asix_common.c:497
BUG: KMSAN: uninit-value in asix_mdio_read+0x3c1/0xb00 drivers/net/usb/asix_common.c:497 drivers/net/usb/asix_common.c:497
 asix_check_host_enable drivers/net/usb/asix_common.c:82 [inline]
 asix_check_host_enable drivers/net/usb/asix_common.c:82 [inline] drivers/net/usb/asix_common.c:497
 asix_mdio_read+0x3c1/0xb00 drivers/net/usb/asix_common.c:497 drivers/net/usb/asix_common.c:497

The Linux kernel CVE team has assigned CVE-2021-47101 to this issue.

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

	Issue introduced in 4.9 with commit d9fe64e51114 and fixed in 5.15.12 with commit d259f621c859
	Issue introduced in 4.9 with commit d9fe64e51114 and fixed in 5.16 with commit 8035b1a2a37a

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-2021-47101
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/usb/asix_common.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/d259f621c85949f30cc578cac813b82bb5169f56
	https://git.kernel.org/stable/c/8035b1a2a37a29d8c717ef84fca8fe7278bc9f03