Subject: CVE-2024-38663: blk-cgroup: fix list corruption from resetting io stat

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

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

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

blk-cgroup: fix list corruption from resetting io stat

Since commit 3b8cc6298724 ("blk-cgroup: Optimize blkcg_rstat_flush()"),
each iostat instance is added to blkcg percpu list, so blkcg_reset_stats()
can't reset the stat instance by memset(), otherwise the llist may be
corrupted.

Fix the issue by only resetting the counter part.

The Linux kernel CVE team has assigned CVE-2024-38663 to this issue.

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

	Issue introduced in 6.2 with commit 3b8cc6298724 and fixed in 6.6.33 with commit d4a60298ac34
	Issue introduced in 6.2 with commit 3b8cc6298724 and fixed in 6.9.4 with commit 89bb36c72e19
	Issue introduced in 6.2 with commit 3b8cc6298724 and fixed in 6.10 with commit 6da668063279

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-2024-38663
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:
	block/blk-cgroup.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/d4a60298ac34f027a09f8f893fdbd9e06279bb24
	https://git.kernel.org/stable/c/89bb36c72e1951843f9e04dc84412e31fcc849a9
	https://git.kernel.org/stable/c/6da6680632792709cecf2b006f2fe3ca7857e791