linux-cve-announce - CVE-2024-26601: ext4: regenerate buddy after block freeing failed if under fc replay

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Date: Sat, 24 Feb 2024 15:57:10 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-26601: ext4: regenerate buddy after block freeing failed if under fc replay

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

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

ext4: regenerate buddy after block freeing failed if under fc replay

This mostly reverts commit 6bd97bf273bd ("ext4: remove redundant
mb_regenerate_buddy()") and reintroduces mb_regenerate_buddy(). Based on
code in mb_free_blocks(), fast commit replay can end up marking as free
blocks that are already marked as such. This causes corruption of the
buddy bitmap so we need to regenerate it in that case.

The Linux kernel CVE team has assigned CVE-2024-26601 to this issue.


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

	Issue introduced in 5.11 with commit 6bd97bf273bd and fixed in 6.1.78 with commit 78327acd4cdc
	Issue introduced in 5.11 with commit 6bd97bf273bd and fixed in 6.6.17 with commit ea42d6cffb0d
	Issue introduced in 5.11 with commit 6bd97bf273bd and fixed in 6.7.5 with commit 6b0d48647935
	Issue introduced in 5.11 with commit 6bd97bf273bd and fixed in 6.8-rc3 with commit c9b528c35795

Please see https://www.kernel.org or 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-2024-26601
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:
	fs/ext4/mballoc.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/78327acd4cdc4a1601af718b781eece577b6b7d4
	https://git.kernel.org/stable/c/ea42d6cffb0dd27a417f410b9d0011e9859328cb
	https://git.kernel.org/stable/c/6b0d48647935e4b8c7b75d1eccb9043fcd4ee581
	https://git.kernel.org/stable/c/c9b528c35795b711331ed36dc3dbee90d5812d4e