CVE-2026-89961

A flaw was found in the Linux kernel's powerpc/mm component. An error in how physical frame number (PFN) offsets are tracked during compound page population can lead to incorrect memory management decisions. This issue could potentially result in system instability or a denial of service.

Wrong addr_pfn tracking in powerpc compound vmemmap population can make the code compute pfn_offset from the wrong PFN and choose the wrong head or tail struct page mapping. This affects low level memory metadata for compound pages on powerpc Book3S64 radix systems with vmemmap optimization. The realistic trigger is local and configuration dependent, usually through privileged memory hotplug or device memory setup rather than a normal unprivileged syscall. For the CVSS the PR:L in the paranoid score reflects deployments where limited host management roles or service accounts can trigger memory add or device memory setup without full root equivalence. The issue is not network reachable. Impact is at least denial of service via kernel crash, and in the worst defensible case may affect confidentiality and integrity because incorrect struct page metadata mapping is a memory corruption candidate.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.