UBUNTU-CVE-2026-89568: Low severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: kho: fix size calculation in khopreservedmemoryreserve() khopreservedmemoryreserve() calculates the size of a preservation by doing 1 << (order + PAGESHIFT). Since the '1' is a 32-bit integer, it can only be shifted by 31. That is, it will only work for preservations up to 2 GiB. Larger preservations will trigger undefined behaviour. While preservations larger than 2 GiB can't be obtained via folios currently, they can be obtained via khopreservepages(). For example, memblock reservemem uses khopreservepages(). Reservations larger than 2 GiB are valid and will trigger this bug if properly aligned. Fix it by using 1UL for shifting.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
In the Linux kernel function kho_preserved_memory_reserve(), change the size calculation from 1 << (order + PAGE_SHIFT) to 1UL << (order + PAGE_SHIFT) to support preservations larger than 2 GiB.