{"cve":"CVE-2026-74481","nvd":{"published":"2026-08-15T13:17:52.930","modified":"2026-10-16T20:17:31.093","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/page_reporting: use system_freezable_wq to fix UAF during suspend\n\nDuring PM freeze (e.g.  S3 suspend or S4 hibernation), device drivers like\nvirtio_balloon reset their underlying virtio devices and delete their\nvirtqueues via vdev->config->del_vqs().\n\nHowever, page reporting work (page_reporting_process) was scheduled on the\nglobal system_wq.  Because system_wq lacks the WQ_FREEZABLE flag, the PM\nfreezer skips it, leaving page_reporting_process active during suspend.\n\nIf pages are freed into the buddy allocator while suspending (for example,\nwhen core MM invokes the balloon shrinker during S4 hibernation image\nsaving), page reporting triggers virtballoon_free_page_report() on deleted\nvirtqueues, resulting in a Use-After-Free / General Protection Fault:\n\n    [  196.795226] general protection fault, probably for non-canonical address 0xaa1436fe70dae6df: 0000 [#1] SMP NOPTI\n    [  196.825967] Workqueue: events page_reporting_process\n    [  196.831038] RIP: 0010:virtqueue_add_split+0x233/0x4c0 [virtio_ring]\n    [  196.927073] virtballoon_free_page_report+0x3a/0xe0 [virtio_balloon]\n    [  196.946943] page_reporting_process+0x370/0x4f0\n\nFix this by switching page reporting work to system_freezable_wq.  This\nensures that the PM freezer pauses page_reporting_process before device\ndrivers destroy their reporting virtqueues.  Because the reporting worker\nis frozen, memory reclamation/freeing (e.g.  via shrinker execution) can\nsafely return pages to MM during freeze without triggering unfrozen\nreporting work on deleted virtqueues.\n\nThis aligns with the driver's existing design. The comment in\nvirtballoon_freeze() states:\n    /*\n     * The workqueue is already frozen by the PM core before this\n     * function is called.\n     */\n\nTesting:\nI have verified these fixes using Google’s virtualization infrastructure\nby running continuous suspend/resume iterations (40+ cycles) while\nchurning memory using stress-ng (`stress-ng --vm 4 --vm-bytes 60%\n--timeout 1`) to constantly create free pages for the buddy allocator.  We\nalso set the `page_reporting_order` parameter to 0 to make the page\nreporting worker highly sensitive, forcing it to pick up any 4K free\npages.  This confirmed that the UAF crashes are no longer reproducible.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":[],"references":["https://git.kernel.org/stable/c/0b45f6927a14914ff685fe0e6f9d11232a1e03df","https://git.kernel.org/stable/c/450f35f4d5a682a0796757e52295df58ddb63bc9","https://git.kernel.org/stable/c/992f270fd808338fbae1f498a5e325e7e2e20368","https://git.kernel.org/stable/c/a4c60046052777ca1dcc83fe3ece2a5136b301f1","https://git.kernel.org/stable/c/b11907c905fa08eda925395f0724b7a409870f65"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:49:10.689564601+00:00"},"epss":{"cve":"CVE-2026-74481","score":0.00132,"percentile":0.0276,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}