Subject: CVE-2021-47470: mm, slub: fix potential use-after-free in slab_debugfs_fops

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

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

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

mm, slub: fix potential use-after-free in slab_debugfs_fops

When sysfs_slab_add failed, we shouldn't call debugfs_slab_add() for s
because s will be freed soon.  And slab_debugfs_fops will use s later
leading to a use-after-free.

The Linux kernel CVE team has assigned CVE-2021-47470 to this issue.

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

	Issue introduced in 5.14 with commit 64dd68497be7 and fixed in 5.14.15 with commit 159d8cfbd042
	Issue introduced in 5.14 with commit 64dd68497be7 and fixed in 5.15 with commit 67823a544414

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-2021-47470
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:
	mm/slub.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/159d8cfbd0428d487c53be4722f33cdab0d25d83
	https://git.kernel.org/stable/c/67823a544414def2a36c212abadb55b23bcda00c