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CVE PROGRAM SOURCE RECORD7.8 High

CVE-2026-74481

mm/page_reporting: use system_freezable_wq to fix UAF during suspend

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: mm/page_reporting: use system_freezable_wq to fix UAF during suspend During PM freeze (e.g. S3 suspend or S4 hibernation), device drivers like virtio_balloon reset their underlying virtio devices and delete their virtqueues via vdev->config->del_vqs(). However, page reporting work (page_reporting_process) was scheduled on the global system_wq. Because system_wq lacks the WQ_FREEZABLE flag, the PM freezer skips it, leaving page_reporting_process active during suspend. If pages are freed into the buddy allocator while suspending (for example, when core MM invokes the balloon shrinker during S4 hibernation image saving), page reporting triggers virtballoon_free_page_report() on deleted virtqueues, resulting in a Use-After-Free / General Protection Fault: [ 196.795226] general protection fault, probably for non-canonical address 0xaa1436fe70dae6df: 0000 [#1] SMP NOPTI [ 196.825967] Workqueue: events page_reporting_process [ 196.831038] RIP: 0010:virtqueue_add_split+0x233/0x4c0 [virtio_ring] [ 196.927073] virtballoon_free_page_report+0x3a/0xe0 [virtio_balloon] [ 196.946943] page_reporting_process+0x370/0x4f0 Fix this by switching page reporting work to system_freezable_wq. This ensures that the PM freezer pauses page_reporting_process before device drivers destroy their reporting virtqueues. Because the reporting worker is frozen, memory reclamation/freeing (e.g. via shrinker execution) can safely return pages to MM during freeze without triggering unfrozen reporting work on deleted virtqueues. This aligns with the driver's existing design. The comment in virtballoon_freeze() states: /* * The workqueue is already frozen by the PM core before this * function is called. */ Testing: I have verified these fixes using Google’s virtualization infrastructure by running continuous suspend/resume iterations (40+ cycles) while churning memory using stress-ng (`stress-ng --vm 4 --vm-bytes 60% --timeout 1`) to constantly create free pages for the buddy allocator. We also set the `page_reporting_order` parameter to 0 to make the page reporting worker highly sensitive, forcing it to pick up any 4K free pages. This confirmed that the UAF crashes are no longer reproducible.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 36e66c554b5c6a9d17a229faca7a61693527b0bd to < a4c60046052777ca1dcc83fe3ece2a5136b301f1affected
  • 36e66c554b5c6a9d17a229faca7a61693527b0bd to < b2c094e98f8bb823b3ae475f7169fe2091c40c6daffected
  • 36e66c554b5c6a9d17a229faca7a61693527b0bd to < 992f270fd808338fbae1f498a5e325e7e2e20368affected
  • 36e66c554b5c6a9d17a229faca7a61693527b0bd to < f978048326570047e8216e81a67f9c71ef2bb1b1affected
  • 36e66c554b5c6a9d17a229faca7a61693527b0bd to < 450f35f4d5a682a0796757e52295df58ddb63bc9affected
  • 36e66c554b5c6a9d17a229faca7a61693527b0bd to < b11907c905fa08eda925395f0724b7a409870f65affected
  • 36e66c554b5c6a9d17a229faca7a61693527b0bd to < faf439b5fa7b231120eac4f7a617e0bfd4f6f5c7affected
  • 36e66c554b5c6a9d17a229faca7a61693527b0bd to < 0b45f6927a14914ff685fe0e6f9d11232a1e03dfaffected

Linux Linux

Default version status: affected

  • 5.7affected
  • 0 to < 5.7unaffected
  • 5.10.265 to ≤ 5.10.*unaffected
  • 5.15.216 to ≤ 5.15.*unaffected
  • 6.1.183 to ≤ 6.1.*unaffected
  • 6.6.151 to ≤ 6.6.*unaffected
  • 6.12.103 to ≤ 6.12.*unaffected
  • 6.18.44 to ≤ 6.18.*unaffected
  • 7.1.8 to ≤ 7.1.*unaffected
  • 7.2 to ≤ *unaffected

References