Bug 2554884 (CVE-2026-98477)

Summary: CVE-2026-98477 kernel: perf/core: Fix NULL pmu_ctx passed to pmu->sched_task()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's performance monitoring subsystem (perf). When switching tasks during performance event handling, the kernel can pass an uninitialized NULL pointer to hardware performance monitoring drivers. A local user can exploit this issue during task execution to trigger a kernel crash, resulting in a Denial of Service (DoS).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-10-18 15:25:15 UTC 
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.
Comment 1 Mauro Matteo Cascella 2026-10-20 10:14:50 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98477.mbox