Subject: CVE-2024-44938: jfs: Fix shift-out-of-bounds in dbDiscardAG

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

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

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

jfs: Fix shift-out-of-bounds in dbDiscardAG

When searching for the next smaller log2 block, BLKSTOL2() returned 0,
causing shift exponent -1 to be negative.

This patch fixes the issue by exiting the loop directly when negative
shift is found.

The Linux kernel CVE team has assigned CVE-2024-44938 to this issue.

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

	Fixed in 6.1.107 with commit bd04a149e3a2
	Fixed in 6.6.47 with commit f650148b4394
	Fixed in 6.10.6 with commit 234e6ea0855c
	Fixed in 6.11 with commit 7063b80268e2

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-2024-44938
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/jfs/jfs_dmap.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/bd04a149e3a29e7f71b7956ed41dba34e42d539e
	https://git.kernel.org/stable/c/f650148b43949ca9e37e820804bb6026fff404f3
	https://git.kernel.org/stable/c/234e6ea0855cdb5673d54ecaf7dc5c78f3e84630
	https://git.kernel.org/stable/c/7063b80268e2593e58bee8a8d709c2f3ff93e2f2