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CVE Record

CVE-2024-36908: blk-iocost: do not WARN if iocg was already offlined

In the Linux kernel, the following vulnerability has been resolved: blk-iocost: do not WARN if iocg was already offlined In iocg_pay_debt(), warn is triggered if 'active_list' is empty, which is intended to confirm iocg is active when it has debt. However, warn can be triggered during a blkcg or disk removal, if iocg_waitq_timer_fn() is run at that time: WARNING: CPU: 0 PID: 2344971 at block/blk-iocost.c:1402 iocg_pay_debt+0x14c/0x190 Call trace: iocg_pay_debt+0x14c/0x190 iocg_kick_waitq+0x438/0x4c0 iocg_waitq_timer_fn+0xd8/0x130 __run_hrtimer+0x144/0x45c __hrtimer_run_queues+0x16c/0x244 hrtimer_interrupt+0x2cc/0x7b0 The warn in this situation is meaningless. Since this iocg is being removed, the state of the 'active_list' is irrelevant, and 'waitq_timer' is canceled after removing 'active_list' in ioc_pd_free(), which ensures iocg is freed after iocg_waitq_timer_fn() returns. Therefore, add the check if iocg was already offlined to avoid warn when removing a blkcg or disk.

HighCVSS 7.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue involves blk-iocost, a block I/O cost controller component. Under block cgroup or disk removal, a timer path can trigger a kernel warning after the object is already being offlined. The CVE is scored high, but the supplied description frames the fix as avoiding a meaningless warning during teardown.

Executive priority

Treat this as a high-priority kernel maintenance item, especially for shared infrastructure. There is no sourced evidence of active exploitation, but kernel bugs with local low-privilege vectors deserve timely patching through standard OS update channels.

Technical view

The flaw is in iocg_pay_debt() within block/blk-iocost.c. iocg_waitq_timer_fn() can run while a blkcg or disk is being removed, causing a WARN when active_list is empty even though the iocg is already offlined. The fix adds an offline-state check before warning.

Likely exposure

Exposure is limited to Linux systems running affected kernel versions or unpatched downstream builds. Practical exposure is more relevant on multi-user, container, or hosting systems where local users can reach kernel block I/O control paths. Distribution backports may change version-based status.

Exploitation context

The CVSS vector indicates local, low-privilege access with no user interaction. The supplied bundle does not cite active exploitation, and KEV status is false. The sources do not provide a demonstrated exploit path beyond the kernel warning condition during removal.

Researcher notes

The source text emphasizes suppressing an invalid WARN when an iocg is already offlined. The CVSS claims confidentiality and availability impact, but the provided description does not explain the concrete impact mechanism. Validate against upstream commits and downstream advisories before asserting exploitability.

Mitigation direction

  • Apply vendor kernel updates that include the referenced stable fixes.
  • Use distribution security packages rather than raw upstream version matching.
  • Prioritize shared Linux hosts, container platforms, and storage-heavy systems.
  • Check Debian LTS advisories if running affected Debian kernels.
  • Monitor vendor guidance for backport status and operational mitigations.

Validation and detection

  • Inventory Linux kernel versions and distribution package revisions.
  • Confirm whether the referenced stable commits are present or backported.
  • Review kernel logs for blk-iocost WARN traces during teardown.
  • Check whether blk-iocost and block cgroups are used in production.
  • Verify patched kernels in staging before broad rollout.
Prepared
Confidence
medium
Sources
10

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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CVE-2024-36908 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.1 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

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.

1CVSS vectors
3Timeline events
2ADP providers
9Source links

SSVC decision data

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

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.1CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H1.85.2CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

7.1High
CVSS 3.1 vector shape for CVE-2024-36908Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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
cvssV3_1other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux7caa47151ab2e644dd221f741ec7578d9532c9a3, 7caa47151ab2e644dd221f741ec7578d9532c9a3, 7caa47151ab2e644dd221f741ec7578d9532c9a3, 7caa47151ab2e644dd221f741ec7578d9532c9a3, 7caa47151ab2e644dd221f741ec7578d9532c9a3, 7caa47151ab2e644dd221f741ec7578d9532c9a3unaffected
LinuxLinux5.4, 0, 5.10.237, 5.15.181, 6.1.135, 6.6.31, 6.8.10, 6.9affected
Weakness

CWE details

No CWE listed

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