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CVE Record

CVE-2021-47364: comedi: Fix memory leak in compat_insnlist()

In the Linux kernel, the following vulnerability has been resolved: comedi: Fix memory leak in compat_insnlist() `compat_insnlist()` handles the 32-bit version of the `COMEDI_INSNLIST` ioctl (whenwhen `CONFIG_COMPAT` is enabled). It allocates memory to temporarily hold an array of `struct comedi_insn` converted from the 32-bit version in user space. This memory is only being freed if there is a fault while filling the array, otherwise it is leaked. Add a call to `kfree()` to fix the leak.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-47364 is a Linux kernel memory leak in COMEDI 32-bit compatibility ioctl handling. The public record describes a missing free after converting user-supplied instruction lists. No CVSS score, CWE, or active exploitation evidence is provided in the source bundle.

Executive priority

Treat this as routine kernel hygiene unless your environment relies on COMEDI or exposes 32-bit compatibility ioctl paths. There is no supplied evidence of active exploitation, but affected kernels should still be patched through standard maintenance.

Technical view

The issue is in compat_insnlist(), used for the 32-bit COMEDI_INSNLIST ioctl when CONFIG_COMPAT is enabled. Temporary kernel memory allocated for converted struct comedi_insn entries was freed only on a fault path, not after normal processing. Stable kernel commits add the missing kfree().

Likely exposure

Exposure appears limited to Linux systems using affected kernel versions with COMEDI ioctl compatibility handling reachable. The source does not identify specific distributions, devices, default configurations, or whether unprivileged users can reach the path.

Exploitation context

The CVE is not listed as KEV in the supplied data, and the bundle provides no public exploitation claim. The described weakness is a memory leak, but practical exploitability and operational impact are not quantified.

Researcher notes

The source bundle is narrow: it identifies the leaking function, condition, and stable commits, but omits CVSS, CWE, exploitability, privilege requirements, and distribution mapping. Avoid over-scoping beyond COMEDI compat ioctl handling.

Mitigation direction

  • Upgrade to a kernel or distribution package containing the referenced stable fixes.
  • Check Linux vendor advisories for backported fixes in supported distribution kernels.
  • Prioritize systems where COMEDI drivers and 32-bit compatibility are enabled.
  • Track remediation through normal kernel patch management and reboot procedures.

Validation and detection

  • Inventory kernel versions against the affected version data in the CVE record.
  • Confirm whether CONFIG_COMPAT is enabled on relevant Linux hosts.
  • Identify hosts using COMEDI-related kernel functionality or drivers.
  • Verify vendor kernel changelogs include the referenced stable fix commits.
Prepared
Confidence
medium
Sources
5

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2021-47364 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
4Source 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

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxb8d47d8813055ce38c0d2ad913d5462017e52692, b8d47d8813055ce38c0d2ad913d5462017e52692, b8d47d8813055ce38c0d2ad913d5462017e52692unaffected
LinuxLinux5.8, 0, 5.10.70, 5.14.9, 5.15affected
Weakness

CWE details

No CWE listed

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