---
id: "CVE-2026-98477"
kind: "vulnerability"
aliases: ["CVE-2026-98477"]
title: "Linux kernel perf: NULL pointer dereference crashes ARM64 systems with BRBE"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["arm64", "bare-metal", "infrastructure", "linux-kernel", "perf"]
not_affected_if: ["kernel-older-than-6.17", "no-brbe-hardware", "x86-64"]
published_at: "2026-10-18T16:16:58+00:00"
first_seen_at: "2026-10-23T21:57:15+00:00"
updated_at: "2026-10-25T05:25:56+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98477", "first_seen_at": "2026-10-23T21:57:15+00:00"}]
---

# Linux kernel perf: NULL pointer dereference crashes ARM64 systems with BRBE

A bug in the Linux kernel's perf subsystem passes a NULL context pointer to the ARM PMU scheduling callback, causing a kernel oops. The sources describe a crash on systems using BRBE (ARM branch record buffer), and do not describe code execution.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `uname -r` and check whether the kernel is at or after v6.17 with the BRBE-enabled ARMv8 PMU driver present
- unknown for a precise check of the fixed kernel version

## Fix

- Update to a Linux kernel release that includes the upstream commit 'perf/core: Fix NULL pmu_ctx passed to pmu->sched_task()'
- unknown for the exact patched version numbers

## Timeline

- 2026-10-23T21:57:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98477

## From the sources

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

perf/core: Fix NULL pmu_ctx passed to pmu->sched_task()

perf_pmu_sched_task() returns early when cpuctx->task_ctx is set, and
cpc->task_epc is only non-NULL while a task context is scheduled in on
this CPU. __perf_pmu_sched_task() therefore always passes NULL:

  Unable to handle kernel NULL pointer dereference at virtual address 00
  pc : armv8pmu_sched_task+0x14/0x50
  Call trace:
   armv8pmu_sched_task+0x14/0x50 (P)
   perf_pmu_sched_task+0xac/0x108
   __perf_event_task_sched_out+0x6c/0xe0

Pass &cpc->epc instead, the CPU-wide context for this PMU, which the
function already dereferences a few lines up to find pmu.

armv8pmu_sched_task() is the only in-tree implementation that
dereferences the argument, and it only reads ->pmu, so the oops needs
BRBE, added in v6.17.

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