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

ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters()

On some machines the number of listed CPUs may be bigger than the actual
CPUs that exist. The tracing subsystem allocates a per_cpu directory with
access to the per CPU ring buffer via a cpuX file. But to save space, the
ring buffer will only allocate buffers for online CPUs, even though the
CPU array will be as big as the nr_cpu_ids.

With the addition of waking waiters on the ring buffer when closing the
file, the ring_buffer_wake_waiters() now needs to make sure that the
buffer is allocated (with the irq_work allocated with it) before trying to
wake waiters, as it will cause a NULL pointer dereference.

While debugging this, I added a NULL check for the buffer itself (which is
OK to do), and also NULL pointer checks against buffer->buffers (which is
not fine, and will WARN) as well as making sure the CPU number passed in
is within the nr_cpu_ids (which is also not fine if it isn't).


Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=1204705
Published: 2025-05-01
Score: 5.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
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Remediation

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Tracking

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Advisories
Source ID Title
EUVD EUVD EUVD-2025-12881 In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters() On some machines the number of listed CPUs may be bigger than the actual CPUs that exist. The tracing subsystem allocates a per_cpu directory with access to the per CPU ring buffer via a cpuX file. But to save space, the ring buffer will only allocate buffers for online CPUs, even though the CPU array will be as big as the nr_cpu_ids. With the addition of waking waiters on the ring buffer when closing the file, the ring_buffer_wake_waiters() now needs to make sure that the buffer is allocated (with the irq_work allocated with it) before trying to wake waiters, as it will cause a NULL pointer dereference. While debugging this, I added a NULL check for the buffer itself (which is OK to do), and also NULL pointer checks against buffer->buffers (which is not fine, and will WARN) as well as making sure the CPU number passed in is within the nr_cpu_ids (which is also not fine if it isn't). Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=1204705
History

Wed, 01 Oct 2025 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 17 Jun 2025 16:30:00 +0000

Type Values Removed Values Added
Metrics threat_severity

Moderate

 threat_severity

Low

Wed, 07 May 2025 13:45:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses CWE-476
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel

Fri, 02 May 2025 14:00:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Thu, 01 May 2025 14:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters() On some machines the number of listed CPUs may be bigger than the actual CPUs that exist. The tracing subsystem allocates a per_cpu directory with access to the per CPU ring buffer via a cpuX file. But to save space, the ring buffer will only allocate buffers for online CPUs, even though the CPU array will be as big as the nr_cpu_ids. With the addition of waking waiters on the ring buffer when closing the file, the ring_buffer_wake_waiters() now needs to make sure that the buffer is allocated (with the irq_work allocated with it) before trying to wake waiters, as it will cause a NULL pointer dereference. While debugging this, I added a NULL check for the buffer itself (which is OK to do), and also NULL pointer checks against buffer->buffers (which is not fine, and will WARN) as well as making sure the CPU number passed in is within the nr_cpu_ids (which is also not fine if it isn't). Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=1204705
Title ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters()
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-11T19:08:42.117Z

Reserved: 2025-05-01T14:05:17.242Z

Link: CVE-2022-49889

cve-icon Vulnrichment

Updated: 2025-10-01T14:24:14.607Z

cve-icon NVD

Status : Modified

Published: 2025-05-01T15:16:13.897

Modified: 2025-10-01T17:15:36.950

Link: CVE-2022-49889

cve-icon Redhat

Severity : Low

Publid Date: 2025-05-01T00:00:00Z

Links: CVE-2022-49889 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses