Subject: CVE-2021-47073: platform/x86: dell-smbios-wmi: Fix oops on rmmod dell_smbios

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

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

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

platform/x86: dell-smbios-wmi: Fix oops on rmmod dell_smbios

init_dell_smbios_wmi() only registers the dell_smbios_wmi_driver on systems
where the Dell WMI interface is supported. While exit_dell_smbios_wmi()
unregisters it unconditionally, this leads to the following oops:

[  175.722921] ------------[ cut here ]------------
[  175.722925] Unexpected driver unregister!
[  175.722939] WARNING: CPU: 1 PID: 3630 at drivers/base/driver.c:194 driver_unregister+0x38/0x40
...
[  175.723089] Call Trace:
[  175.723094]  cleanup_module+0x5/0xedd [dell_smbios]
...
[  175.723148] ---[ end trace 064c34e1ad49509d ]---

Make the unregister happen on the same condition the register happens
to fix this.

The Linux kernel CVE team has assigned CVE-2021-47073 to this issue.

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

	Issue introduced in 4.15 with commit 1a258e670434 and fixed in 4.19.192 with commit 75cfc833da4a
	Issue introduced in 4.15 with commit 1a258e670434 and fixed in 5.4.122 with commit 6fa78a6b9a3b
	Issue introduced in 4.15 with commit 1a258e670434 and fixed in 5.10.40 with commit 0cf036a0d325
	Issue introduced in 4.15 with commit 1a258e670434 and fixed in 5.12.7 with commit 8d746ea7c687
	Issue introduced in 4.15 with commit 1a258e670434 and fixed in 5.13 with commit 3a53587423d2

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-2021-47073
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/platform/x86/dell/dell-smbios-wmi.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/75cfc833da4a2111106d4c134e93e0c7f41e35e7
	https://git.kernel.org/stable/c/6fa78a6b9a3beb676a010dc489c1257f7e432525
	https://git.kernel.org/stable/c/0cf036a0d325200e6c27b90908e51195bbc557b1
	https://git.kernel.org/stable/c/8d746ea7c687bab060a2c05a35c449302406cd52
	https://git.kernel.org/stable/c/3a53587423d25c87af4b4126a806a0575104b45e