# CVE-2022-49889: linux: In the Linux kernel, the following vulnerability has been resolved:  ring-buffer: Check for NULL cpu_buffer in ring_b...

CVE-2022-49889 is fixed in linux on 1 platform, first by DEBIAN-CVE-2022-49889, released May 1, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-49889
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0020
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 1, 2025

## 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

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.0.8-1 | [DEBIAN-CVE-2022-49889](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49889.md) | May 1, 2025 |
| Linux | linux Debian 13.5 (trixie) | 6.0.8-1 | [DEBIAN-CVE-2022-49889](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49889.md) | May 1, 2025 |
| Linux | linux Debian 14 | 6.0.8-1 | [DEBIAN-CVE-2022-49889](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49889.md) | May 1, 2025 |

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