Subject: CVE-2021-47385: hwmon: (w83792d) 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: (w83792d) Fix NULL pointer dereference by removing unnecessary structure field

If driver read val value sufficient for
(val & 0x08) && (!(val & 0x80)) && ((val & 0x7) == ((val >> 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 multipline alignment]

The Linux kernel CVE team has assigned CVE-2021-47385 to this issue.

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

	Fixed in 5.4.151 with commit 200ced5ba724
	Fixed in 5.10.71 with commit 1499bb2c3a87
	Fixed in 5.14.10 with commit 24af1fe376e2
	Fixed in 5.15 with commit 0f36b88173f0

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-2021-47385
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/w83792d.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/200ced5ba724d8bbf29dfac4ed1e17a39ccaccd1
	https://git.kernel.org/stable/c/1499bb2c3a87a2efea0065adab2bd66badee61c3
	https://git.kernel.org/stable/c/24af1fe376e22c42238a4a604d31e46c486876c3
	https://git.kernel.org/stable/c/0f36b88173f028e372668ae040ab1a496834d278