Subject: CVE-2024-42079: gfs2: Fix NULL pointer dereference in gfs2_log_flush

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

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

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

gfs2: Fix NULL pointer dereference in gfs2_log_flush

In gfs2_jindex_free(), set sdp->sd_jdesc to NULL under the log flush
lock to provide exclusion against gfs2_log_flush().

In gfs2_log_flush(), check if sdp->sd_jdesc is non-NULL before
dereferencing it.  Otherwise, we could run into a NULL pointer
dereference when outstanding glock work races with an unmount
(glock_work_func -> run_queue -> do_xmote -> inode_go_sync ->
gfs2_log_flush).

The Linux kernel CVE team has assigned CVE-2024-42079 to this issue.

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

	Fixed in 6.6.37 with commit 3429ef5f5090
	Fixed in 6.9.8 with commit f54f9d5368a4
	Fixed in 6.10 with commit 35264909e9d1

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-2024-42079
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/gfs2/log.c
	fs/gfs2/super.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/3429ef5f50909cee9e498c50f0c499b9397116ce
	https://git.kernel.org/stable/c/f54f9d5368a4e92ede7dd078a62788dae3a7c6ef
	https://git.kernel.org/stable/c/35264909e9d1973ab9aaa2a1b07cda70f12bb828