CVE-2024-42234
mm: fix crashes from deferred split racing folio migration
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
0Exploited in Wild
-Decision
Descriptions
In the Linux kernel, the following vulnerability has been resolved:
mm: fix crashes from deferred split racing folio migration
Even on 6.10-rc6, I've been seeing elusive "Bad page state"s (often on
flags when freeing, yet the flags shown are not bad: PG_locked had been
set and cleared??), and VM_BUG_ON_PAGE(page_ref_count(page) == 0)s from
deferred_split_scan()'s folio_put(), and a variety of other BUG and WARN
symptoms implying double free by deferred split and large folio migration.
6.7 commit 9bcef5973e31 ("mm: memcg: fix split queue list crash when large
folio migration") was right to fix the memcg-dependent locking broken in
85ce2c517ade ("memcontrol: only transfer the memcg data for migration"),
but missed a subtlety of deferred_split_scan(): it moves folios to its own
local list to work on them without split_queue_lock, during which time
folio->_deferred_list is not empty, but even the "right" lock does nothing
to secure the folio and the list it is on.
Fortunately, deferred_split_scan() is careful to use folio_try_get(): so
folio_migrate_mapping() can avoid the race by folio_undo_large_rmappable()
while the old folio's reference count is temporarily frozen to 0 - adding
such a freeze in the !mapping case too (originally, folio lock and
unmapping and no swap cache left an anon folio unreachable, so no freezing
was needed there: but the deferred split queue offers a way to reach it).
CVSS Scores
SSVC
- Decision:Track
Timeline
- 2024-07-30 CVE Reserved
- 2024-08-07 CVE Published
- 2024-08-13 EPSS Updated
- 2024-12-19 CVE Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
CAPEC
References (3)
URL | Tag | Source |
---|---|---|
https://git.kernel.org/stable/c/9bcef5973e31020e5aa8571eb994d67b77318356 | Vuln. Introduced |
URL | Date | SRC |
---|
URL | Date | SRC |
---|---|---|
https://git.kernel.org/stable/c/fc7facce686b64201dbf0b9614cc1d0bfad70010 | 2024-07-18 | |
https://git.kernel.org/stable/c/be9581ea8c058d81154251cb0695987098996cad | 2024-07-06 |
URL | Date | SRC |
---|
Affected Vendors, Products, and Versions
Vendor | Product | Version | Other | Status | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 6.7 < 6.9.10 Search vendor "Linux" for product "Linux Kernel" and version " >= 6.7 < 6.9.10" | en |
Affected
| ||||||
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 6.7 < 6.10 Search vendor "Linux" for product "Linux Kernel" and version " >= 6.7 < 6.10" | en |
Affected
|