CVE-2025-39859: ptp: ocp: fix use-after-free bugs causing by ptp_ocp_watchdog

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-19 · updated 2026-10-30
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: ptp: ocp: fix use-after-free bugs causing by ptp_ocp_watchdog The ptp_ocp_detach() only shuts down the watchdog timer if it is pending. However, if the timer handler is already running, the timer_delete_sync() is not called. This leads to race conditions where the devlink that contains the ptp_ocp is deallocated while the timer handler is still accessing it, resulting in use-after-free bugs. The following details one of the race scenarios. (thread 1) | (thread 2) ptp_ocp_remove() | ptp_ocp_detach() | ptp_ocp_watchdog() if (timer_pending(&bp->watchdog))| bp = timer_container_of() timer_delete_sync() | | devlink_free(devlink) //free | | bp-> //use Resolve this by unconditionally calling timer_delete_sync() to ensure the timer is reliably deactivated, preventing any access after free.

Affected products

Linux kernel: from 5.15 before 6.16.6; 6.17-rc1, 6.17-rc2, 6.17-rc3, 6.17-rc4 — fixed in 6.16.6
Linux: 5.15 — fixed in 6.17

How to fix

Upgrade to a fixed version: Linux kernel 6.16.6; Linux 6.17. Check the vendor advisory for mitigations.

References

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