{"id":"CVE-2026-74481","title":"mm/page_reporting: use system_freezable_wq to fix UAF during suspend","summary":"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 th…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < a4c60046052777ca1dcc83fe3ece2a5136b301f1","Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < b2c094e98f8bb823b3ae475f7169fe2091c40c6d","Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < 992f270fd808338fbae1f498a5e325e7e2e20368","Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < f978048326570047e8216e81a67f9c71ef2bb1b1","Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < 450f35f4d5a682a0796757e52295df58ddb63bc9","Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < b11907c905fa08eda925395f0724b7a409870f65","Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < faf439b5fa7b231120eac4f7a617e0bfd4f6f5c7","Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < 0b45f6927a14914ff685fe0e6f9d11232a1e03df","Linux 5.7"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T18:57:45.101951Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T19:05:48.983Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74481","references":[{"url":"https://git.kernel.org/stable/c/a4c60046052777ca1dcc83fe3ece2a5136b301f1"},{"url":"https://git.kernel.org/stable/c/b2c094e98f8bb823b3ae475f7169fe2091c40c6d"},{"url":"https://git.kernel.org/stable/c/992f270fd808338fbae1f498a5e325e7e2e20368"},{"url":"https://git.kernel.org/stable/c/f978048326570047e8216e81a67f9c71ef2bb1b1"},{"url":"https://git.kernel.org/stable/c/450f35f4d5a682a0796757e52295df58ddb63bc9"},{"url":"https://git.kernel.org/stable/c/b11907c905fa08eda925395f0724b7a409870f65"},{"url":"https://git.kernel.org/stable/c/faf439b5fa7b231120eac4f7a617e0bfd4f6f5c7"},{"url":"https://git.kernel.org/stable/c/0b45f6927a14914ff685fe0e6f9d11232a1e03df"}],"tags":["cve.org"],"epss":0.00132,"epssPercentile":0.02478,"ingestedAt":"2026-10-16T19:46:24.356Z","slug":"CVE-2026-74481","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < a4c60046052777ca1dcc83fe3ece2a5136b301f1`\n- `Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < b2c094e98f8bb823b3ae475f7169fe2091c40c6d`\n- `Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < 992f270fd808338fbae1f498a5e325e7e2e20368`\n- `Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < f978048326570047e8216e81a67f9c71ef2bb1b1`\n- `Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < 450f35f4d5a682a0796757e52295df58ddb63bc9`\n- `Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < b11907c905fa08eda925395f0724b7a409870f65`\n- `Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < faf439b5fa7b231120eac4f7a617e0bfd4f6f5c7`\n- `Linux >= 36e66c554b5c6a9d17a229faca7a61693527b0bd < 0b45f6927a14914ff685fe0e6f9d11232a1e03df`\n- `Linux 5.7`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}