CVE-2025-38055 Affecting kernel6.12-modules-extra package, versions <0:6.12.31-35.92.amzn2023


Severity

Recommended
0.0
high
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.02% (5th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNEL612MODULESEXTRA-10694442
  • published11 Jul 2025
  • disclosed18 Jun 2025

Introduced: 18 Jun 2025

NewCVE-2025-38055  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.12-modules-extra to version 0:6.12.31-35.92.amzn2023 or higher.
This issue was patched in ALAS2023-2025-1052.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel6.12-modules-extra package and not the kernel6.12-modules-extra package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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

perf/x86/intel: Fix segfault with PEBS-via-PT with sample_freq

Currently, using PEBS-via-PT with a sample frequency instead of a sample period, causes a segfault. For example:

BUG: kernel NULL pointer dereference, address: 0000000000000195
&lt;NMI&gt;
? __die_body.cold+0x19/0x27
? page_fault_oops+0xca/0x290
? exc_page_fault+0x7e/0x1b0
? asm_exc_page_fault+0x26/0x30
? intel_pmu_pebs_event_update_no_drain+0x40/0x60
? intel_pmu_pebs_event_update_no_drain+0x32/0x60
intel_pmu_drain_pebs_icl+0x333/0x350
handle_pmi_common+0x272/0x3c0
intel_pmu_handle_irq+0x10a/0x2e0
perf_event_nmi_handler+0x2a/0x50

That happens because intel_pmu_pebs_event_update_no_drain() assumes all the pebs_enabled bits represent counter indexes, which is not always the case. In this particular case, bits 60 and 61 are set for PEBS-via-PT purposes.

The behaviour of PEBS-via-PT with sample frequency is questionable because although a PMI is generated (PEBS_PMI_AFTER_EACH_RECORD), the period is not adjusted anyway.

Putting that aside, fix intel_pmu_pebs_event_update_no_drain() by passing the mask of counter bits instead of 'size'. Note, prior to the Fixes commit, 'size' would be limited to the maximum counter index, so the issue was not hit.

CVSS Base Scores

version 3.1