cbcvebase.
CVE-2024-42234
published 2024-08-07

CVE-2024-42234: 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…

PriorityP419medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.19%
9.3th percentile
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).

Affected

8 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.9.10-1 (forky)linux 6.9.10-1 (forky)
linuxlinux
linuxlinux>= 9bcef5973e31020e5aa8571eb994d67b77318356 < fc7facce686b64201dbf0b9614cc1d0bfad70010fc7facce686b64201dbf0b9614cc1d0bfad70010
linuxlinux>= 9bcef5973e31020e5aa8571eb994d67b77318356 < be9581ea8c058d81154251cb0695987098996cadbe9581ea8c058d81154251cb0695987098996cad
linuxlinux_kernel>= 0 < 6.9.10-16.9.10-1
linuxlinux_kernel>= 0 < 6.9.10-16.9.10-1
linuxlinux_kernel>= 0 < 6.8.0-48.486.8.0-48.48
linuxlinux_kernel>= 6.7 < 6.9.106.9.10

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.5MEDIUM
vendor_debian5.5LOW
vendor_redhat5.5MEDIUM
vendor_ubuntu5.5MEDIUM
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