CVE-2025-37949 Affecting kernel-devel-matched package, versions *


Severity

Recommended
medium

Based on Red Hat Enterprise Linux security rating.

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  • Snyk IDSNYK-RHEL9-KERNELDEVELMATCHED-10191455
  • published21 May 2025
  • disclosed20 May 2025

Introduced: 20 May 2025

NewCVE-2025-37949  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 kernel-devel-matched.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-devel-matched package and not the kernel-devel-matched 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:

xenbus: Use kref to track req lifetime

Marek reported seeing a NULL pointer fault in the xenbus_thread callstack: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x180 Call Trace: <TASK> __wake_up_common_lock+0x82/0xd0 process_msg+0x18e/0x2f0 xenbus_thread+0x165/0x1c0

process_msg+0x18e is req->cb(req). req->cb is set to xs_wake_up(), a thin wrapper around wake_up(), or xenbus_dev_queue_reply(). It seems like it was xs_wake_up() in this case.

It seems like req may have woken up the xs_wait_for_reply(), which kfree()ed the req. When xenbus_thread resumes, it faults on the zero-ed data.

Linux Device Drivers 2nd edition states: "Normally, a wake_up call can cause an immediate reschedule to happen, meaning that other processes might run before wake_up returns." ... which would match the behaviour observed.

Change to keeping two krefs on each request. One for the caller, and one for xenbus_thread. Each will kref_put() when finished, and the last will free it.

This use of kref matches the description in Documentation/core-api/kref.rst

CVSS Base Scores

version 3.1