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CVE Record

CVE-2021-47278: bus: mhi: pci_generic: Fix possible use-after-free in mhi_pci_remove()

In the Linux kernel, the following vulnerability has been resolved: bus: mhi: pci_generic: Fix possible use-after-free in mhi_pci_remove() This driver's remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver's remove function has finished, which would result in a use-after-free. Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.

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 driver cleanup bug. When an affected MHI PCI generic device is removed, a timer can keep running after driver memory is freed, creating a possible use-after-free. The sources do not show active exploitation, CVSS, or impact beyond the kernel fix description.

Executive priority

Treat as a patch-management item for Linux fleets, not an emergency based on supplied evidence. Prioritize affected systems using the relevant driver, especially production hosts where kernel crashes or device instability would disrupt operations.

Technical view

In mhi_pci_remove(), the driver used del_timer(), which may return while the timer callback is still executing. The callback could then access freed driver state after removal. The kernel fix replaces it with del_timer_sync() so the handler has finished and cannot re-schedule itself.

Likely exposure

Exposure is likely limited to systems running affected Linux kernels with the MHI PCI generic driver and relevant hardware or device paths. The supplied affected data names Linux kernel 5.12, 5.12.11, and 5.13 entries, but downstream package status must be checked.

Exploitation context

The source bundle provides no evidence of active exploitation, public exploit availability, or CISA KEV listing. The described trigger is in the driver remove path, so practical exposure depends on local hardware, driver use, and device removal conditions.

Researcher notes

The key evidence is the upstream stable fix description. No CVSS, CWE, exploit signal, or detailed attack preconditions are supplied. Validation should focus on kernel version lineage, downstream backports, and whether the relevant MHI PCI generic code is reachable.

Mitigation direction

  • Update to a kernel containing the referenced stable fixes.
  • Check your Linux distribution advisory for the exact fixed package version.
  • Prioritize systems using MHI PCI generic hardware or modules.
  • If patch timing is constrained, review vendor guidance for temporary risk reduction.

Validation and detection

  • Inventory kernels against distribution advisories for CVE-2021-47278.
  • Confirm whether the MHI PCI generic driver is present or loaded.
  • Verify the kernel includes the del_timer_sync() fix in mhi_pci_remove().
  • Review crash logs for timer or MHI PCI removal faults.
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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CVE-2021-47278 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
3Source 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
LinuxLinux8562d4fe34a3ef52da077f77985994bb9ad1f83e, 8562d4fe34a3ef52da077f77985994bb9ad1f83eunaffected
LinuxLinux5.12, 0, 5.12.11, 5.13affected
Weakness

CWE details

No CWE listed

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