linux-cve-announce - CVE-2024-57892: ocfs2: fix slab-use-after-free due to dangling pointer dqi

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Message-ID: <2025011513-CVE-2024-57892-6d53@gregkh>
Date: Wed, 15 Jan 2025 14:06:15 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-57892: ocfs2: fix slab-use-after-free due to dangling pointer dqi_priv

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

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

ocfs2: fix slab-use-after-free due to dangling pointer dqi_priv

When mounting ocfs2 and then remounting it as read-only, a
slab-use-after-free occurs after the user uses a syscall to
quota_getnextquota.  Specifically, sb_dqinfo(sb, type)->dqi_priv is the
dangling pointer.

During the remounting process, the pointer dqi_priv is freed but is never
set as null leaving it to be accessed.  Additionally, the read-only option
for remounting sets the DQUOT_SUSPENDED flag instead of setting the
DQUOT_USAGE_ENABLED flags.  Moreover, later in the process of getting the
next quota, the function ocfs2_get_next_id is called and only checks the
quota usage flags and not the quota suspended flags.

To fix this, I set dqi_priv to null when it is freed after remounting with
read-only and put a check for DQUOT_SUSPENDED in ocfs2_get_next_id.

[akpm@...ux-foundation.org: coding-style cleanups]

The Linux kernel CVE team has assigned CVE-2024-57892 to this issue.

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

	Issue introduced in 4.6 with commit 8f9e8f5fcc059a3cba87ce837c88316797ef3645 and fixed in 6.6.70 with commit 2e3d203b1adede46bbba049e497765d67865be18
	Issue introduced in 4.6 with commit 8f9e8f5fcc059a3cba87ce837c88316797ef3645 and fixed in 6.12.9 with commit ba950a02d8d23811aa1120affd3adedcfac6153d
	Issue introduced in 4.6 with commit 8f9e8f5fcc059a3cba87ce837c88316797ef3645 and fixed in 6.13-rc6 with commit 5f3fd772d152229d94602bca243fbb658068a597

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-2024-57892
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/ocfs2/quota_global.c
	fs/ocfs2/quota_local.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/2e3d203b1adede46bbba049e497765d67865be18
	https://git.kernel.org/stable/c/ba950a02d8d23811aa1120affd3adedcfac6153d
	https://git.kernel.org/stable/c/5f3fd772d152229d94602bca243fbb658068a597