Divide By Zero Affecting kernel-64k-debug package, versions <0:5.14.0-284.82.1.el9_2


Severity

Recommended
0.0
medium
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-RHEL9-KERNEL64KDEBUG-7888504
  • published4 Sept 2024
  • disclosed30 Jul 2024

Introduced: 30 Jul 2024

CVE-2024-42102  (opens in a new tab)
CWE-369  (opens in a new tab)

How to fix?

Upgrade RHEL:9 kernel-64k-debug to version 0:5.14.0-284.82.1.el9_2 or higher.
This issue was patched in RHSA-2024:6267.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-64k-debug package and not the kernel-64k-debug package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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

Revert "mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again"

Patch series "mm: Avoid possible overflows in dirty throttling".

Dirty throttling logic assumes dirty limits in page units fit into 32-bits. This patch series makes sure this is true (see patch 2/2 for more details).

This patch (of 2):

This reverts commit 9319b647902cbd5cc884ac08a8a6d54ce111fc78.

The commit is broken in several ways. Firstly, the removed (u64) cast from the multiplication will introduce a multiplication overflow on 32-bit archs if wb_thresh * bg_thresh >= 1<<32 (which is actually common - the default settings with 4GB of RAM will trigger this). Secondly, the div64_u64() is unnecessarily expensive on 32-bit archs. We have div64_ul() in case we want to be safe & cheap. Thirdly, if dirty thresholds are larger than 1<<32 pages, then dirty balancing is going to blow up in many other spectacular ways anyway so trying to fix one possible overflow is just moot.

CVSS Scores

version 3.1