CVE-2026-98729: x86/mm: Don't apply va_align to hugetlb mappings on AMD F15h

CVE-2026-98729: x86/mm: Don't apply va_align to hugetlb mappings on AMD F15h

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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. ]

The Linux kernel CVE team has assigned CVE-2026-98729 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.13 with commit 1317a5e7f7b1336eac4097f0ef4f5cd7ae72f1d0 and fixed in 6.18.56 with commit fe23680e6f1d52b8cc45d77bf7c54249508a81c7
	Issue introduced in 6.13 with commit 1317a5e7f7b1336eac4097f0ef4f5cd7ae72f1d0 and fixed in 7.2.10 with commit b46b2e2de47ca9449532b0a7110ed99f79061d6e
	Issue introduced in 6.13 with commit 1317a5e7f7b1336eac4097f0ef4f5cd7ae72f1d0 and fixed in 7.3-rc6 with commit d2457a7e2727dc747a61a50d65c2f259afce8c45

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-98729
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	arch/x86/kernel/sys_x86_64.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/fe23680e6f1d52b8cc45d77bf7c54249508a81c7
	https://git.kernel.org/stable/c/b46b2e2de47ca9449532b0a7110ed99f79061d6e
	https://git.kernel.org/stable/c/d2457a7e2727dc747a61a50d65c2f259afce8c45