CVE-2025-38305 Affecting kernel-64k-modules package, versions *


Severity

Recommended
medium

Based on Red Hat Enterprise Linux security rating.

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  • Snyk IDSNYK-RHEL9-KERNEL64KMODULES-10702665
  • published11 Jul 2025
  • disclosed10 Jul 2025

Introduced: 10 Jul 2025

NewCVE-2025-38305  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 kernel-64k-modules.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-64k-modules package and not the kernel-64k-modules package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

ptp: remove ptp->n_vclocks check logic in ptp_vclock_in_use()

There is no disagreement that we should check both ptp->is_virtual_clock and ptp->n_vclocks to check if the ptp virtual clock is in use.

However, when we acquire ptp->n_vclocks_mux to read ptp->n_vclocks in ptp_vclock_in_use(), we observe a recursive lock in the call trace starting from n_vclocks_store().

============================================ WARNING: possible recursive locking detected 6.15.0-rc6 #1 Not tainted

syz.0.1540/13807 is trying to acquire lock: ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_vclock_in_use drivers/ptp/ptp_private.h:103 [inline] ffff888035a24868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: ptp_clock_unregister+0x21/0x250 drivers/ptp/ptp_clock.c:415

but task is already holding lock: ffff888030704868 (&ptp->n_vclocks_mux){+.+.}-{4:4}, at: n_vclocks_store+0xf1/0x6d0 drivers/ptp/ptp_sysfs.c:215

other info that might help us debug this: Possible unsafe locking scenario:

   CPU0
   ----

lock(&ptp->n_vclocks_mux); lock(&ptp->n_vclocks_mux);

*** DEADLOCK *** ....

The best way to solve this is to remove the logic that checks ptp->n_vclocks in ptp_vclock_in_use().

The reason why this is appropriate is that any path that uses ptp->n_vclocks must unconditionally check if ptp->n_vclocks is greater than 0 before unregistering vclocks, and all functions are already written this way. And in the function that uses ptp->n_vclocks, we already get ptp->n_vclocks_mux before unregistering vclocks.

Therefore, we need to remove the redundant check for ptp->n_vclocks in ptp_vclock_in_use() to prevent recursive locking.

CVSS Base Scores

version 3.1