SB20260912198 - Integer underflow in Linux kernel mm

Description

This security bulletin contains information about 1 vulnerability.

1) Integer underflow (CVE-ID: CVE-2026-89593)

CWE-ID: CWE-191 - Integer underflow

CVSSv4: 0 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a local user to cause incorrect huge-page reservation accounting.

The vulnerability exists due to an integer underflow in __unmap_hugepage_range() in the hugetlb memory-management component when unmapping a parent range whose folio remains mapped by a child. A local user can unmap the parent range before the child range to cause the reserved count to underflow.

The reserved count is restored when the child unmaps the range.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/0f001491e5a2ec69aa9d5dd6b799e5742245f9ea
• https://git.kernel.org/stable/c/5120b1e048d48596ffaec1a8412012a91adba73b
• https://git.kernel.org/stable/c/a3c65af20cceb7f997847727636b4017326f845d