Subject: CVE-2024-26774: ext4: avoid dividing by 0 in mb_update_avg_fragment_size() when block bitmap corrupt

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

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

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

ext4: avoid dividing by 0 in mb_update_avg_fragment_size() when block bitmap corrupt

Determine if bb_fragments is 0 instead of determining bb_free to eliminate
the risk of dividing by zero when the block bitmap is corrupted.

The Linux kernel CVE team has assigned CVE-2024-26774 to this issue.

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

	Fixed in 5.15.150 with commit 687061cfaa2a
	Fixed in 6.1.80 with commit 8b40eb2e716b
	Fixed in 6.6.19 with commit f32d2a745b02
	Fixed in 6.7.7 with commit 8cf9cc602cfb
	Fixed in 6.8 with commit 993bf0f4c393

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-2024-26774
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/ext4/mballoc.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/687061cfaa2ac3095170e136dd9c29a4974f41d4
	https://git.kernel.org/stable/c/8b40eb2e716b503f7a4e1090815a17b1341b2150
	https://git.kernel.org/stable/c/f32d2a745b02123258026e105a008f474f896d6a
	https://git.kernel.org/stable/c/8cf9cc602cfb40085967c0d140e32691c8b71cf3
	https://git.kernel.org/stable/c/993bf0f4c393b3667830918f9247438a8f6fdb5b