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CVE Record

CVE-2021-47077: scsi: qedf: Add pointer checks in qedf_update_link_speed()

In the Linux kernel, the following vulnerability has been resolved: scsi: qedf: Add pointer checks in qedf_update_link_speed() The following trace was observed: [ 14.042059] Call Trace: [ 14.042061] <IRQ> [ 14.042068] qedf_link_update+0x144/0x1f0 [qedf] [ 14.042117] qed_link_update+0x5c/0x80 [qed] [ 14.042135] qed_mcp_handle_link_change+0x2d2/0x410 [qed] [ 14.042155] ? qed_set_ptt+0x70/0x80 [qed] [ 14.042170] ? qed_set_ptt+0x70/0x80 [qed] [ 14.042186] ? qed_rd+0x13/0x40 [qed] [ 14.042205] qed_mcp_handle_events+0x437/0x690 [qed] [ 14.042221] ? qed_set_ptt+0x70/0x80 [qed] [ 14.042239] qed_int_sp_dpc+0x3a6/0x3e0 [qed] [ 14.042245] tasklet_action_common.isra.14+0x5a/0x100 [ 14.042250] __do_softirq+0xe4/0x2f8 [ 14.042253] irq_exit+0xf7/0x100 [ 14.042255] do_IRQ+0x7f/0xd0 [ 14.042257] common_interrupt+0xf/0xf [ 14.042259] </IRQ> API qedf_link_update() is getting called from QED but by that time shost_data is not initialised. This results in a NULL pointer dereference when we try to dereference shost_data while updating supported_speeds. Add a NULL pointer check before dereferencing shost_data.

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 bug in the qedf SCSI path. During a link update, the driver can dereference an uninitialized pointer and crash the kernel. The business impact is mainly availability risk on hosts that load this driver, not confirmed data theft or privilege escalation from the provided sources.

Executive priority

Treat as targeted infrastructure hygiene unless critical systems depend on the qedf driver. Patch during the next maintenance cycle, escalating if affected storage or network paths are business-critical.

Technical view

qedf_link_update() can be called from QED before shost_data is initialized. qedf_update_link_speed() then dereferences shost_data while updating supported_speeds, causing a NULL pointer dereference in IRQ context. The fix adds a NULL pointer check before dereferencing shost_data.

Likely exposure

Exposure appears limited to Linux systems using the qedf driver path. The provided version data is incomplete and should be validated against the running kernel tree, distro advisories, and whether qedf/qed modules are present or loaded.

Exploitation context

The source bundle provides a kernel trace and fix rationale, but no evidence of active exploitation. KEV is false, and no cited source states public exploit availability or real-world abuse.

Researcher notes

The record lacks CVSS, CWE, and detailed distro ranges. Analysis should focus on driver reachability, module load state, and whether downstream kernels include commits a6362a737572, 11014efcec37, or 73578af92a0f.

Mitigation direction

  • Check vendor or distribution advisories for patched kernel packages.
  • Update affected Linux kernels to a release containing the referenced stable fixes.
  • Disable or avoid loading qedf where it is not operationally required.
  • Prioritize hosts where qedf/qed modules are loaded or hardware depends on them.

Validation and detection

  • Inventory kernels and confirm whether qedf or qed modules are present.
  • Check whether affected hosts run source or packages containing the stable fix commits.
  • Review boot and kernel logs for NULL pointer dereference traces involving qedf_link_update.
  • Validate remediation in staging with link-change and reboot scenarios.
Prepared
Confidence
medium
Sources
5

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-2021-47077 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
4Source 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
LinuxLinux61d8658b4a435eac729966cc94cdda077a8df5cd, 61d8658b4a435eac729966cc94cdda077a8df5cd, 61d8658b4a435eac729966cc94cdda077a8df5cdunaffected
LinuxLinux4.11, 0, 5.10.40, 5.12.7, 5.13affected
Weakness

CWE details

No CWE listed

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