Subject: CVE-2024-39472: xfs: fix log recovery buffer allocation for the legacy h_size fixup

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

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

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

xfs: fix log recovery buffer allocation for the legacy h_size fixup

Commit a70f9fe52daa ("xfs: detect and handle invalid iclog size set by
mkfs") added a fixup for incorrect h_size values used for the initial
umount record in old xfsprogs versions.  Later commit 0c771b99d6c9
("xfs: clean up calculation of LR header blocks") cleaned up the log
reover buffer calculation, but stoped using the fixed up h_size value
to size the log recovery buffer, which can lead to an out of bounds
access when the incorrect h_size does not come from the old mkfs
tool, but a fuzzer.

Fix this by open coding xlog_logrec_hblks and taking the fixed h_size
into account for this calculation.

The Linux kernel CVE team has assigned CVE-2024-39472 to this issue.

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

	Issue introduced in 5.10 with commit 0c771b99d6c9 and fixed in 5.15.165 with commit f754591b17d0
	Issue introduced in 5.10 with commit 0c771b99d6c9 and fixed in 6.1.105 with commit 57835c0e7152
	Issue introduced in 5.10 with commit 0c771b99d6c9 and fixed in 6.6.46 with commit c2389c074973
	Issue introduced in 5.10 with commit 0c771b99d6c9 and fixed in 6.10 with commit 45cf976008dd

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-2024-39472
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/xfs_log_recover.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/f754591b17d0ee91c2b45fe9509d0cdc420527cb
	https://git.kernel.org/stable/c/57835c0e7152e36b03875dd6c56dfeed685c1b1f
	https://git.kernel.org/stable/c/c2389c074973aa94e34992e7f66dac0de37595b5
	https://git.kernel.org/stable/c/45cf976008ddef4a9c9a30310c9b4fb2a9a6602a