Subject: CVE-2021-47384: hwmon: (w83793) Fix NULL pointer dereference by removing unnecessary structure field

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

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

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

hwmon: (w83793) Fix NULL pointer dereference by removing unnecessary structure field

If driver read tmp value sufficient for
(tmp & 0x08) && (!(tmp & 0x80)) && ((tmp & 0x7) == ((tmp >> 4) & 0x7))
from device then Null pointer dereference occurs.
(It is possible if tmp = 0b0xyz1xyz, where same literals mean same numbers)
Also lm75[] does not serve a purpose anymore after switching to
devm_i2c_new_dummy_device() in w83791d_detect_subclients().

The patch fixes possible NULL pointer dereference by removing lm75[].

Found by Linux Driver Verification project (linuxtesting.org).

[groeck: Dropped unnecessary continuation lines, fixed multi-line alignments]

The Linux kernel CVE team has assigned CVE-2021-47384 to this issue.

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

	Fixed in 5.4.151 with commit 6cb01fe630ea
	Fixed in 5.10.71 with commit 7c4fd5de39f2
	Fixed in 5.14.10 with commit 746011193f44
	Fixed in 5.15 with commit dd4d747ef05a

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-2021-47384
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/hwmon/w83793.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/6cb01fe630eaffc5a2c3f7364436caddba286623
	https://git.kernel.org/stable/c/7c4fd5de39f273626a2b0f3a446d2cc85cd47616
	https://git.kernel.org/stable/c/746011193f44f97f8784edcf8327c587946745fc
	https://git.kernel.org/stable/c/dd4d747ef05addab887dc8ff0d6ab9860bbcd783