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CVE Record

CVE-2021-47554: vdpa_sim: avoid putting an uninitialized iova_domain

In the Linux kernel, the following vulnerability has been resolved: vdpa_sim: avoid putting an uninitialized iova_domain The system will crash if we put an uninitialized iova_domain, this could happen when an error occurs before initializing the iova_domain in vdpasim_create(). BUG: kernel NULL pointer dereference, address: 0000000000000000 ... RIP: 0010:__cpuhp_state_remove_instance+0x96/0x1c0 ... Call Trace: <TASK> put_iova_domain+0x29/0x220 vdpasim_free+0xd1/0x120 [vdpa_sim] vdpa_release_dev+0x21/0x40 [vdpa] device_release+0x33/0x90 kobject_release+0x63/0x160 vdpasim_create+0x127/0x2a0 [vdpa_sim] vdpasim_net_dev_add+0x7d/0xfe [vdpa_sim_net] vdpa_nl_cmd_dev_add_set_doit+0xe1/0x1a0 [vdpa] genl_family_rcv_msg_doit+0x112/0x140 genl_rcv_msg+0xdf/0x1d0 ... So we must make sure the iova_domain is already initialized before put it. In addition, we may get the following warning in this case: WARNING: ... drivers/iommu/iova.c:344 iova_cache_put+0x58/0x70 So we must make sure the iova_cache_put() is invoked only if the iova_cache_get() is already invoked. Let's fix it together.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel crash bug in the vDPA simulator code. If an error happens before an IOVA domain is initialized, cleanup can dereference a null pointer and crash the system. The public sources describe availability impact, not data theft or remote compromise.

Executive priority

Treat this as a targeted kernel availability risk, not an emergency internet-scale issue based on current evidence. Patch through normal Linux kernel maintenance, with higher priority for shared, lab, virtualization, or development hosts using vDPA simulator functionality.

Technical view

The issue is in vdpa_sim error handling around vdpasim_create() and vdpasim_free(). Cleanup may call put_iova_domain() and iova_cache_put() before the matching initialization/get path completed, producing a kernel NULL pointer dereference and warning in iova.c. Stable kernel commits correct the initialization checks.

Likely exposure

Exposure is most likely on Linux systems running affected kernels where vdpa_sim or vdpa_sim_net is present and used. The source bundle lists Linux kernel versions including 5.13, 5.15.6, and 5.16 as affected, but does not provide distribution-specific package status.

Exploitation context

No provided source states active exploitation, and CISA KEV status is false. The evidence shows a crash during vDPA simulator device creation error handling. Required attacker access, privileges, and practical exploitability are not specified in the bundle.

Researcher notes

The supplied trace ties the crash to premature cleanup of an uninitialized iova_domain and unmatched iova_cache_put(). The available data does not establish attacker prerequisites, namespace constraints, or remote reachability. Validation should focus on kernel lineage, module availability, and vendor backports.

Mitigation direction

  • Update to a vendor kernel containing the referenced stable fixes.
  • Check your Linux distribution advisory for backported package versions.
  • Avoid using vDPA simulator modules where they are unnecessary.
  • Prioritize systems where local users can manage vDPA devices.

Validation and detection

  • Inventory kernel versions against vendor advisories for CVE-2021-47554.
  • Check whether vdpa_sim or vdpa_sim_net is loaded or packaged.
  • Confirm patched kernels include the referenced stable commits or vendor backports.
  • Review kernel logs for NULL dereference traces involving vdpasim_create or put_iova_domain.
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
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

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4080fc1067501707b9693b8003feae7d50d14e35, 4080fc1067501707b9693b8003feae7d50d14e35unaffected
LinuxLinux5.13, 0, 5.15.6, 5.16affected
Weakness

CWE details

No CWE listed

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