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CVE Record

CVE-2022-48821: misc: fastrpc: avoid double fput() on failed usercopy

In the Linux kernel, the following vulnerability has been resolved: misc: fastrpc: avoid double fput() on failed usercopy If the copy back to userland fails for the FASTRPC_IOCTL_ALLOC_DMA_BUFF ioctl(), we shouldn't assume that 'buf->dmabuf' is still valid. In fact, dma_buf_fd() called fd_install() before, i.e. "consumed" one reference, leaving us with none. Calling dma_buf_put() will therefore put a reference we no longer own, leading to a valid file descritor table entry for an already released 'file' object which is a straight use-after-free. Simply avoid calling dma_buf_put() and rely on the process exit code to do the necessary cleanup, if needed, i.e. if the file descriptor is still valid.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2022-48821 is a Linux kernel FASTRPC bug where an error path can release a file object twice after a failed copy back to user space. That can create a use-after-free condition inside the kernel. The sources do not provide CVSS, confirmed exploitation, or a complete product impact statement.

Executive priority

Treat as a kernel maintenance and exposure-reduction issue until vendor scoring is available. Prioritize patch confirmation on shared systems, devices with untrusted local workloads, and environments where kernel compromise would materially affect business operations.

Technical view

In FASTRPC_IOCTL_ALLOC_DMA_BUFF, dma_buf_fd() may consume the buffer reference through fd_install(). If the subsequent usercopy fails, calling dma_buf_put() again releases a reference the code no longer owns, leaving a valid file descriptor table entry pointing to a freed file object.

Likely exposure

Exposure appears limited to Linux kernels that include the vulnerable FASTRPC ioctl path and make the relevant device interface accessible to userland. The bundle lists Linux kernel affected entries, but exact downstream distribution status must be confirmed with vendor kernel advisories.

Exploitation context

The source bundle does not cite active exploitation, public exploit code, or KEV listing. The bug is a kernel use-after-free reachable through an ioctl error path, so local access to the relevant FASTRPC interface is the key exposure question.

Researcher notes

Evidence supports a reference-counting error in the FASTRPC DMA buffer allocation ioctl cleanup path. The record lacks CVSS, CWE, exploit status, and downstream package mapping. Avoid assuming remote reachability or specific distributions without separate vendor evidence.

Mitigation direction

  • Update affected Linux kernels to vendor-supported builds containing the stable FASTRPC fix.
  • Check Linux distribution advisories for exact fixed package versions.
  • Restrict access to FASTRPC device nodes where operationally feasible.
  • Prioritize systems exposing the interface to untrusted local users or workloads.

Validation and detection

  • Inventory running kernel versions and compare against vendor advisories for CVE-2022-48821.
  • Confirm whether FASTRPC support and device nodes exist on target systems.
  • Review kernel package changelogs for the referenced stable commits.
  • Validate that untrusted users cannot access the relevant ioctl interface unnecessarily.
Prepared
Confidence
medium
Sources
7

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.

ATT&CK lookup starting points

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CVE-2022-48821 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
6Source 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
LinuxLinux6cffd79504ce040f460831030d3069fa1c99bb71, 6cffd79504ce040f460831030d3069fa1c99bb71, 6cffd79504ce040f460831030d3069fa1c99bb71, 6cffd79504ce040f460831030d3069fa1c99bb71, 6cffd79504ce040f460831030d3069fa1c99bb71unaffected
LinuxLinux5.1, 0, 5.4.180, 5.10.101, 5.15.24, 5.16.10, 5.17affected
Weakness

CWE details

No CWE listed

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