linux-cve-announce - CVE-2026-23097: migrate: correct lock ordering for hugetlb file folios

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <2026020427-CVE-2026-23097-a591@gregkh>
Date: Wed,  4 Feb 2026 17:14:56 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23097: migrate: correct lock ordering for hugetlb file folios

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

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

In the Linux kernel, the following vulnerability has been resolved:

migrate: correct lock ordering for hugetlb file folios

Syzbot has found a deadlock (analyzed by Lance Yang):

1) Task (5749): Holds folio_lock, then tries to acquire i_mmap_rwsem(read lock).
2) Task (5754): Holds i_mmap_rwsem(write lock), then tries to acquire
folio_lock.

migrate_pages()
  -> migrate_hugetlbs()
    -> unmap_and_move_huge_page()     <- Takes folio_lock!
      -> remove_migration_ptes()
        -> __rmap_walk_file()
          -> i_mmap_lock_read()       <- Waits for i_mmap_rwsem(read lock)!

hugetlbfs_fallocate()
  -> hugetlbfs_punch_hole()           <- Takes i_mmap_rwsem(write lock)!
    -> hugetlbfs_zero_partial_page()
     -> filemap_lock_hugetlb_folio()
      -> filemap_lock_folio()
        -> __filemap_get_folio        <- Waits for folio_lock!

The migration path is the one taking locks in the wrong order according to
the documentation at the top of mm/rmap.c.  So expand the scope of the
existing i_mmap_lock to cover the calls to remove_migration_ptes() too.

This is (mostly) how it used to be after commit c0d0381ade79.  That was
removed by 336bf30eb765 for both file & anon hugetlb pages when it should
only have been removed for anon hugetlb pages.

The Linux kernel CVE team has assigned CVE-2026-23097 to this issue.


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

	Issue introduced in 5.10 with commit 336bf30eb76580b579dc711ded5d599d905c0217 and fixed in 6.6.122 with commit 526394af4e8ade89cacd1a9ce2b97712712fcc34
	Issue introduced in 5.10 with commit 336bf30eb76580b579dc711ded5d599d905c0217 and fixed in 6.12.68 with commit b75070823b89009f5123fd0e05a8e0c3d39937c1
	Issue introduced in 5.10 with commit 336bf30eb76580b579dc711ded5d599d905c0217 and fixed in 6.18.8 with commit 1b68efce6dd483d22f50d0d3800c4cfda14b1305
	Issue introduced in 5.10 with commit 336bf30eb76580b579dc711ded5d599d905c0217 and fixed in 6.19-rc7 with commit b7880cb166ab62c2409046b2347261abf701530e
	Issue introduced in 5.9.9 with commit ef792d6ce0db6a56e56743b1de1716a982c3b851

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-2026-23097
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:
	mm/migrate.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/526394af4e8ade89cacd1a9ce2b97712712fcc34
	https://git.kernel.org/stable/c/b75070823b89009f5123fd0e05a8e0c3d39937c1
	https://git.kernel.org/stable/c/1b68efce6dd483d22f50d0d3800c4cfda14b1305
	https://git.kernel.org/stable/c/b7880cb166ab62c2409046b2347261abf701530e