CVE-2022-49549: x86/MCE/AMD: Fix memory leak when threshold_create_bank() fails

CVE-2022-49549: x86/MCE/AMD: Fix memory leak when threshold_create_bank() fails

[Greg Kroah-Hartman]

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

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

x86/MCE/AMD: Fix memory leak when threshold_create_bank() fails

In mce_threshold_create_device(), if threshold_create_bank() fails, the
previously allocated threshold banks array @bp will be leaked because
the call to mce_threshold_remove_device() will not free it.

This happens because mce_threshold_remove_device() fetches the pointer
through the threshold_banks per-CPU variable but bp is written there
only after the bank creation is successful, and not before, when
threshold_create_bank() fails.

Add a helper which unwinds all the bank creation work previously done
and pass into it the previously allocated threshold banks array for
freeing.

  [ bp: Massage. ]

The Linux kernel CVE team has assigned CVE-2022-49549 to this issue.


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

	Issue introduced in 5.8 with commit 6458de97fc15530b54477c4e2b70af653e8ac3d9 and fixed in 5.10.121 with commit b4acb8e7f1594607bc9017ef0aacb40b24a003d6
	Issue introduced in 5.8 with commit 6458de97fc15530b54477c4e2b70af653e8ac3d9 and fixed in 5.15.46 with commit cc0dd4456f9573bf8af9b4d8754433918e809e1e
	Issue introduced in 5.8 with commit 6458de97fc15530b54477c4e2b70af653e8ac3d9 and fixed in 5.17.14 with commit 9708f1956eeb70c86943e0bc62fa3b0101b59616
	Issue introduced in 5.8 with commit 6458de97fc15530b54477c4e2b70af653e8ac3d9 and fixed in 5.18.3 with commit 396b8e7ab2a99ddac57d3522b3da5e58cb608d37
	Issue introduced in 5.8 with commit 6458de97fc15530b54477c4e2b70af653e8ac3d9 and fixed in 5.19 with commit e5f28623ceb103e13fc3d7bd45edf9818b227fd0

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-2022-49549
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:
	arch/x86/kernel/cpu/mce/amd.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/b4acb8e7f1594607bc9017ef0aacb40b24a003d6
	https://git.kernel.org/stable/c/cc0dd4456f9573bf8af9b4d8754433918e809e1e
	https://git.kernel.org/stable/c/9708f1956eeb70c86943e0bc62fa3b0101b59616
	https://git.kernel.org/stable/c/396b8e7ab2a99ddac57d3522b3da5e58cb608d37
	https://git.kernel.org/stable/c/e5f28623ceb103e13fc3d7bd45edf9818b227fd0