migrate: correct lock ordering for hugetlb file folios
Summary
migrate: correct lock ordering for hugetlb file folios
Original description
The description as published by the source.
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):
- Task (5749): Holds folio_lock, then tries to acquire i_mmap_rwsem(read lock).
- 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.
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-23097 linux-lts Fixed in: 6.1.163-r0
- Debian DEBIAN-CVE-2026-23097 linux Fixed in: 5.10.249-1
- Ubuntu UBUNTU-CVE-2026-23097 linux-hwe-edge
References
- advisory github.com
- advisory nvd.nist.gov
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org