mm/page_reporting: use system_freezable_wq to fix UAF during suspend

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74481
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 13:17:52 UTC
Updated2026-08-19 17:21:05 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001320000 probability, percentile 0.031980000 (date 2026-08-19)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 36e66c554b5c6a9d17a229faca7a61693527b0bd a4c60046052777ca1dcc83fe3ece2a5136b301f1 git Not specified
CNA Linux Linux affected 36e66c554b5c6a9d17a229faca7a61693527b0bd b2c094e98f8bb823b3ae475f7169fe2091c40c6d git Not specified
CNA Linux Linux affected 36e66c554b5c6a9d17a229faca7a61693527b0bd 992f270fd808338fbae1f498a5e325e7e2e20368 git Not specified
CNA Linux Linux affected 36e66c554b5c6a9d17a229faca7a61693527b0bd f978048326570047e8216e81a67f9c71ef2bb1b1 git Not specified
CNA Linux Linux affected 36e66c554b5c6a9d17a229faca7a61693527b0bd 450f35f4d5a682a0796757e52295df58ddb63bc9 git Not specified
CNA Linux Linux affected 36e66c554b5c6a9d17a229faca7a61693527b0bd b11907c905fa08eda925395f0724b7a409870f65 git Not specified
CNA Linux Linux affected 36e66c554b5c6a9d17a229faca7a61693527b0bd faf439b5fa7b231120eac4f7a617e0bfd4f6f5c7 git Not specified
CNA Linux Linux affected 36e66c554b5c6a9d17a229faca7a61693527b0bd 0b45f6927a14914ff685fe0e6f9d11232a1e03df git Not specified
CNA Linux Linux affected 5.7 Not specified
CNA Linux Linux unaffected 5.7 semver Not specified
CNA Linux Linux unaffected 5.10.265 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.216 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.151 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.103 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.44 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.8 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b2c094e98f8bb823b3ae475f7169fe2091c40c6d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f978048326570047e8216e81a67f9c71ef2bb1b1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/450f35f4d5a682a0796757e52295df58ddb63bc9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a4c60046052777ca1dcc83fe3ece2a5136b301f1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b11907c905fa08eda925395f0724b7a409870f65 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/992f270fd808338fbae1f498a5e325e7e2e20368 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/faf439b5fa7b231120eac4f7a617e0bfd4f6f5c7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0b45f6927a14914ff685fe0e6f9d11232a1e03df 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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