Описание
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.
A flaw was found in the Linux kernel. A local attacker could exploit a deadlock vulnerability due to incorrect lock ordering between folio_lock and i_mmap_rwsem when migrating hugetlb file-backed folios. This could lead to hung tasks and potential system-wide stalls, resulting in a Denial of Service (DoS).
Отчет
A deadlock can occur when migrating hugetlb file backed folios due to incorrect lock ordering between folio_lock and the mapping i_mmap_rwsem. One task in the migration path can hold folio_lock and then block on i_mmap_lock_read. Another task such as hugetlbfs fallocate or punch hole can hold i_mmap_lock_write and then block on folio_lock. This ABBA pattern can hang tasks indefinitely and lead to a denial of service. For the CVSS the PR is N because the involved operations can be triggered by normal users who can access hugetlbfs and run memory pressure and file operations. The issue is not network reachable. Impact is denial of service due to hung tasks and potential system wide stalls.
Меры по смягчению последствий
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Affected | ||
| Red Hat Enterprise Linux 10 | kernel | Fixed | RHSA-2026:4012 | 09.03.2026 |
| Red Hat Enterprise Linux 8 | kernel-rt | Fixed | RHSA-2026:3463 | 02.03.2026 |
| Red Hat Enterprise Linux 8 | kernel | Fixed | RHSA-2026:3464 | 02.03.2026 |
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2026:3488 | 02.03.2026 |
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2026:3488 | 02.03.2026 |
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Дополнительная информация
Статус:
EPSS
7.3 High
CVSS3
Связанные уязвимости
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()...
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
In the Linux kernel, the following vulnerability has been resolved: m ...
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 exist...
EPSS
7.3 High
CVSS3