CVE-2024-42102

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

Published Jul 30, 2024 CVSS 3.1 · 4.7 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4008-1 linux-6.1 security update
Debian DSA Debian DSA DSA-5747-1 linux security update
Ubuntu USN Ubuntu USN USN-7003-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7003-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7003-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7003-4 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7003-5 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7006-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7007-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7007-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7007-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7009-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7009-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7019-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-4 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-5 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-6 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7089-7 Linux kernel (Low Latency) vulnerabilities
Ubuntu USN Ubuntu USN USN-7090-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7095-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7156-1 Linux kernel (GKE) vulnerabilities
History
Type Values Removed Values Added
Metrics epss

{'score': 0.00077}

epss

{'score': 0.00079}

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

cvssV3_1

{'score': 4.7, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Redhat enterprise Linux
CPEs cpe:/a:redhat:enterprise_linux:9
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat enterprise Linux
Type Values Removed Values Added
First Time appeared Redhat
Redhat rhel Eus
CPEs cpe:/a:redhat:rhel_eus:9.2
cpe:/a:redhat:rhel_eus:9.2::nfv
Vendors & Products Redhat
Redhat rhel Eus
Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses CWE-369
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
May 23, 2026, 3:52 PM
Reserved
Jul 29, 2024, 3:50 PM
Status
Modified
Published
Jul 30, 2024, 8:15 AM
Modified
Jun 17, 2026, 7:48 AM
Severity
Moderate
Public date
Jul 30, 2024, 12:00 AM