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CVE Record

CVE-2025-38620: zloop: fix KASAN use-after-free of tag set

In the Linux kernel, the following vulnerability has been resolved: zloop: fix KASAN use-after-free of tag set When a zoned loop device, or zloop device, is removed, KASAN enabled kernel reports "BUG KASAN use-after-free" in blk_mq_free_tag_set(). The BUG happens because zloop_ctl_remove() calls put_disk(), which invokes zloop_free_disk(). The zloop_free_disk() frees the memory allocated for the zlo pointer. However, after the memory is freed, zloop_ctl_remove() calls blk_mq_free_tag_set(&zlo->tag_set), which accesses the freed zlo. Hence the KASAN use-after-free. zloop_ctl_remove() put_disk(zlo->disk) put_device() kobject_put() ... zloop_free_disk() kvfree(zlo) blk_mq_free_tag_set(&zlo->tag_set) To avoid the BUG, move the call to blk_mq_free_tag_set(&zlo->tag_set) from zloop_ctl_remove() into zloop_free_disk(). This ensures that the tag_set is freed before the call to kvfree(zlo).

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel bug in the zoned loop device cleanup path. Removing a zloop device can access memory after it has already been freed. The provided sources do not describe remote attackability, privilege requirements, real-world exploitation, or business impact beyond the kernel memory-safety failure.

Executive priority

Treat as a kernel maintenance item unless your environment relies on zloop. There is no sourced evidence of active exploitation or remote impact, but kernel memory-safety bugs should be tracked to closure through normal patch governance.

Technical view

zloop_ctl_remove() calls put_disk(), which can invoke zloop_free_disk() and free the zlo structure. It then calls blk_mq_free_tag_set(&zlo->tag_set), dereferencing freed memory. The fix moves tag_set cleanup into zloop_free_disk() before kvfree(zlo).

Likely exposure

Exposure appears limited to Linux systems running the affected 6.16-era kernel versions or listed commit range, especially where zoned loop devices are created and removed. The bundle does not identify affected distributions, configurations, or whether zloop is enabled by default.

Exploitation context

The source bundle reports a KASAN-detected use-after-free during zloop device removal. It does not cite active exploitation, and KEV is false. No public exploit details, exploitability assessment, or attacker prerequisites are provided.

Researcher notes

The evidence is narrow: it documents the root cause and code-ordering fix, but not security impact, privilege boundaries, or exploitability. Analysis should focus on kernel version lineage, zloop availability, and whether removal operations are reachable in the target environment.

Mitigation direction

  • Check vendor or distribution kernel advisories for CVE-2025-38620 coverage.
  • Update to a kernel containing the referenced stable fixes when available.
  • Prioritize hosts that use zoned loop devices or custom kernel testing workflows.
  • If updates are delayed, review whether zloop usage can be avoided operationally.

Validation and detection

  • Inventory Linux kernel versions and compare against the affected range in the CVE record.
  • Confirm whether zloop or zoned loop device functionality is present and used.
  • Verify the referenced stable commits are included in deployed kernel sources or packages.
  • Review kernel logs for KASAN use-after-free reports involving zloop cleanup.
Prepared
Confidence
medium
Sources
4

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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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
0ADP providers
3Source links

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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxeb0570c7df23c2f32fe899fcdaf8fca9a5ecd51e, eb0570c7df23c2f32fe899fcdaf8fca9a5ecd51eunaffected
LinuxLinux6.16, 0, 6.16.1, 6.17affected
Weakness

CWE details

No CWE listed

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