CVE-2025-39700

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

mm/damon/ops-common: ignore migration request to invalid nodes

damon_migrate_pages() tries migration even if the target node is invalid.

If users mistakenly make such invalid requests via

DAMOS_MIGRATE_{HOT,COLD} action, the below kernel BUG can happen.

[ 7831.883495] BUG: unable to handle page fault for address: 0000000000001f48

[ 7831.884160] #PF: supervisor read access in kernel mode

[ 7831.884681] #PF: error_code(0x0000) - not-present page

[ 7831.885203] PGD 0 P4D 0

[ 7831.885468] Oops: Oops: 0000 [#1] SMP PTI

[ 7831.885852] CPU: 31 UID: 0 PID: 94202 Comm: kdamond.0 Not tainted 6.16.0-rc5-mm-new-damon+ #93 PREEMPT(voluntary)

[ 7831.886913] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-4.el9 04/01/2014

[ 7831.887777] RIP: 0010:__alloc_frozen_pages_noprof (include/linux/mmzone.h:1724 include/linux/mmzone.h:1750 mm/page_alloc.c:4936 mm/page_alloc.c:5137)

[...]

[ 7831.895953] Call Trace:

[ 7831.896195] <TASK>

[ 7831.896397] __folio_alloc_noprof (mm/page_alloc.c:5183 mm/page_alloc.c:5192)

[ 7831.896787] migrate_pages_batch (mm/migrate.c:1189 mm/migrate.c:1851)

[ 7831.897228] ? __pfx_alloc_migration_target (mm/migrate.c:2137)

[ 7831.897735] migrate_pages (mm/migrate.c:2078)

[ 7831.898141] ? __pfx_alloc_migration_target (mm/migrate.c:2137)

[ 7831.898664] damon_migrate_folio_list (mm/damon/ops-common.c:321 mm/damon/ops-common.c:354)

[ 7831.899140] damon_migrate_pages (mm/damon/ops-common.c:405)

[...]

Add a target node validity check in damon_migrate_pages(). The validity

check is stolen from that of do_pages_move(), which is being used for the

move_pages() system call.