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
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade bpftool-debuginfoUpgrade kernel-livepatch-5.15.79-51.138Upgrade perf-debuginfoUpgrade kernel-toolsUpgrade bpftoolUpgrade python-perfUpgrade perfUpgrade kernel-debuginfo-common-aarch64Upgrade kernelUpgrade kernel-tools-develUpgrade kernel-headersUpgrade python-perf-debuginfoUpgrade kernel-debuginfoUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-tools-debuginfoUpgrade kernel-devel | May 20, 2026 | May 20, 2026 |
| Debian | — | Upgrade linux | May 5, 2025 | May 1, 2025 |
| Huawei Euleros 2_0_sp11 | — | Upgrade kernelUpgrade kernel-abi-stablelistsUpgrade kernel-toolsUpgrade bpftoolUpgrade kernel-tools-libsUpgrade python3-perf | Aug 13, 2025 | Aug 9, 2025 |
| Huawei Euleros 2_0_sp13 | — | Upgrade bpftoolUpgrade kernelUpgrade kernel-toolsUpgrade kernel-tools-libsUpgrade python3-perfUpgrade kernel-abi-stablelists | Aug 13, 2025 | Aug 9, 2025 |
| Redhat_linux | — | No solution exists | Jul 9, 2025 | May 1, 2025 |
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