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CVE Record

CVE-2024-42102: Revert "mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again"

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2024-42102 is a Linux kernel issue in dirty writeback throttling. The source describes a broken prior fix that can overflow calculations on 32-bit systems, including common 4GB RAM configurations. Business impact is unclear from the sources, but affected Linux kernels should be updated through normal vendor kernel channels.

Executive priority

Treat this as a kernel maintenance and fleet hygiene item unless internal evidence shows affected 32-bit systems are business-critical. There is no sourced active exploitation signal, but kernel arithmetic bugs can create reliability risk in infrastructure that is hard to diagnose later.

Technical view

The kernel reverted commit 9319b647902c because it removed a u64 cast, allowing multiplication overflow in wb_dirty_limits() on 32-bit architectures. The description also notes inefficient division use and broader dirty-balancing assumptions when thresholds exceed 32-bit page limits. No CVSS, CWE, or exploit detail is provided.

Likely exposure

Exposure is limited to Linux systems running affected kernel versions or downstream packages that include the vulnerable dirty throttling change. The source specifically highlights 32-bit architectures, with default settings on 4GB RAM systems as a common trigger condition.

Exploitation context

The provided data says this is not in CISA KEV and gives no evidence of active exploitation or public weaponization. The issue appears to be a kernel logic and arithmetic correctness problem, not a documented remote attack path.

Researcher notes

The record is sparse: no CVSS, CWE, exploitability analysis, or explicit impact statement is provided. The strongest technical evidence is the upstream kernel rationale: overflow on 32-bit architectures after a cast removal, plus concern that dirty-balancing assumptions fail beyond 32-bit page limits.

Mitigation direction

  • Update affected Linux kernels through vendor-supported kernel packages.
  • Track the listed upstream stable commits for branch-specific correction status.
  • For Debian LTS systems, review the cited Debian advisory and apply relevant updates.
  • Prioritize 32-bit Linux systems and embedded fleets for assessment.
  • If no package is available, monitor vendor guidance rather than applying ad hoc fixes.

Validation and detection

  • Inventory Linux kernel versions across servers, appliances, containers hosts, and embedded systems.
  • Identify 32-bit Linux deployments, especially systems near 4GB RAM.
  • Map installed kernels to vendor advisories or the listed upstream stable commits.
  • Confirm distribution packages include the relevant stable kernel fixes.
  • Review monitoring for kernel writeback, throttling, or stability anomalies.
Prepared
Confidence
medium
Sources
11

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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CVE-2024-42102 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
10Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxc593d26fb5d577ef31b6e49a31e08ae3ebc1bc1e, 1f12e4b3284d6c863f272eb2de0d4248ed211cf4, 81e7d2530d458548b90a5c5e76b77ad5e5d1c0df, 5099871b370335809c0fd1abad74d9c7c205d43f, 16b1025eaa8fc223ab4273ece20d1c3a4211a95d, ec18ec230301583395576915d274b407743d8f6c, 9319b647902cbd5cc884ac08a8a6d54ce111fc78, 9319b647902cbd5cc884ac08a8a6d54ce111fc78, 65977bed167a92e87085e757fffa5798f7314c9f, 4.19.307, 5.4.269, 5.10.210, 5.15.149, 6.1.79, 6.6.18, 6.7.6unaffected
LinuxLinux6.8, 0, 4.19.318, 5.4.280, 5.10.222, 5.15.163, 6.1.98, 6.6.39, 6.9.9, 6.10affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.