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CVE Record

CVE-2022-50091: locking/csd_lock: Change csdlock_debug from early_param to __setup

In the Linux kernel, the following vulnerability has been resolved: locking/csd_lock: Change csdlock_debug from early_param to __setup The csdlock_debug kernel-boot parameter is parsed by the early_param() function csdlock_debug(). If set, csdlock_debug() invokes static_branch_enable() to enable csd_lock_wait feature, which triggers a panic on arm64 for kernels built with CONFIG_SPARSEMEM=y and CONFIG_SPARSEMEM_VMEMMAP=n. With CONFIG_SPARSEMEM_VMEMMAP=n, __nr_to_section is called in static_key_enable() and returns NULL, resulting in a NULL dereference because mem_section is initialized only later in sparse_init(). This is also a problem for powerpc because early_param() functions are invoked earlier than jump_label_init(), also resulting in static_key_enable() failures. These failures cause the warning "static key 'xxx' used before call to jump_label_init()". Thus, early_param is too early for csd_lock_wait to run static_branch_enable(), so changes it to __setup to fix these.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue can crash or destabilize some systems during boot when the csdlock_debug boot option is enabled. Exposure appears narrow: it depends on kernel version, architecture, memory configuration, and boot parameters. The source bundle does not show active exploitation or a CVSS score.

Executive priority

Treat as a targeted availability risk for specific Linux infrastructure, not a broad internet-facing emergency. Patch through normal kernel maintenance, with priority for affected architecture/configuration combinations.

Technical view

csdlock_debug was parsed through early_param and called static_branch_enable before required kernel initialization. On arm64 with CONFIG_SPARSEMEM=y and CONFIG_SPARSEMEM_VMEMMAP=n, this can NULL-dereference during boot. On powerpc, it can use static keys before jump_label_init. The fix changes parsing to __setup.

Likely exposure

Likely exposed systems are affected Linux kernel builds using the csdlock_debug boot parameter, especially arm64 sparsemem builds without VMEMMAP and powerpc systems. Remote application exposure is not indicated by the sources.

Exploitation context

No source in the bundle reports active exploitation, and CISA KEV is false. Practical triggering appears tied to boot-time configuration rather than unauthenticated network access.

Researcher notes

The core condition is ordering: early_param runs too early for static_branch_enable in this path. Evidence is strong for mechanism and fix direction, but severity, CVSS, distro package status, and exploitability beyond boot-time triggering are not provided.

Mitigation direction

  • Apply vendor kernel updates that include the referenced stable fixes.
  • Avoid enabling csdlock_debug on affected kernels until patched.
  • Prioritize arm64 and powerpc systems matching the noted kernel configurations.
  • Check Linux distribution advisories for package-specific fixed versions.

Validation and detection

  • Inventory Linux kernel versions against the CVE record and vendor advisories.
  • Review boot parameters for csdlock_debug on Linux hosts.
  • Identify arm64 sparsemem builds without VMEMMAP and relevant powerpc systems.
  • Confirm updated kernels contain one of the referenced stable commits.
Prepared
Confidence
medium
Sources
6

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

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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
5Source 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

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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux8d0968cc6b8ffd8496c2ebffdfdc801f949a85e5, 8d0968cc6b8ffd8496c2ebffdfdc801f949a85e5, 8d0968cc6b8ffd8496c2ebffdfdc801f949a85e5, 8d0968cc6b8ffd8496c2ebffdfdc801f949a85e5unaffected
LinuxLinux5.13, 0, 5.15.61, 5.18.18, 5.19.2, 6.0affected
Weakness

CWE details

No CWE listed

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