linux-cve-announce - CVE-2024-41013: xfs: don't walk off the end of a directory data block

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Message-ID: <2024072908-CVE-2024-41013-2996@gregkh>
Date: Mon, 29 Jul 2024 08:37:09 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-41013: xfs: don't walk off the end of a directory data block

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

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

xfs: don't walk off the end of a directory data block

This adds sanity checks for xfs_dir2_data_unused and xfs_dir2_data_entry
to make sure don't stray beyond valid memory region. Before patching, the
loop simply checks that the start offset of the dup and dep is within the
range. So in a crafted image, if last entry is xfs_dir2_data_unused, we
can change dup->length to dup->length-1 and leave 1 byte of space. In the
next traversal, this space will be considered as dup or dep. We may
encounter an out of bound read when accessing the fixed members.

In the patch, we make sure that the remaining bytes large enough to hold
an unused entry before accessing xfs_dir2_data_unused and
xfs_dir2_data_unused is XFS_DIR2_DATA_ALIGN byte aligned. We also make
sure that the remaining bytes large enough to hold a dirent with a
single-byte name before accessing xfs_dir2_data_entry.

The Linux kernel CVE team has assigned CVE-2024-41013 to this issue.

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

	Fixed in 6.11-rc1 with commit 0c7fcdb6d06c

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-2024-41013
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/xfs/libxfs/xfs_dir2_data.c
	fs/xfs/libxfs/xfs_dir2_priv.h

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/0c7fcdb6d06cdf8b19b57c17605215b06afa864a