Bug 2555163 (CVE-2026-98729)

Summary: CVE-2026-98729 kernel: x86/mm: Don't apply va_align to hugetlb mappings on AMD F15h
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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Doc Text:
A flaw was found in the Linux kernel. On systems utilizing specific AMD processors, improper virtual address alignment for huge page memory mappings can allow a local user to cause a Denial of Service (DoS). When unmapping these misaligned memory ranges during teardown, the kernel encounters an internal assertion failure, resulting in a system crash.
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Description OSIDB Bzimport 2026-10-18 15:57:59 UTC 
In the Linux kernel, the following vulnerability has been resolved:

x86/mm: Don't apply va_align to hugetlb mappings on AMD F15h

get_align_mask() returns huge_page_mask_align() for hugetlbfs, but get_align_bits()
adds va_align.bits regardless, so vm_unmapped_area() returns an address off the huge
page boundary and __unmap_hugepage_range() hits BUG_ON(start & ~huge_page_mask(h)) at
teardown.

This can be triggered on Carrizo and FX-8370E, both hstates.

Pass the file to get_align_bits() and skip the randomisation for hugetlbfs.

  [ bp: Massage commit message. ]
Comment 1 Mauro Matteo Cascella 2026-10-22 23:48:17 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98729.mbox