{"schema":"threatline.record/2","record":{"id":"CVE-2026-97478","aliases":[],"summary":"virt: acrn: Fix irqfd use-after-free during eventfd shutdown","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nvirt: acrn: Fix irqfd use-after-free during eventfd shutdown\n\nacrn_irqfd_deassign() and the eventfd EPOLLHUP wakeup can race and free\nthe same struct hsm_irqfd:\n\n  CPU0                                 CPU1\n  ----                                 ----\n  eventfd_release()\n    wake_up_poll(EPOLLHUP)\n      hsm_irqfd_wakeup()\n        queue_work(&irqfd->shutdown)\n                                       acrn_irqfd_deassign()\n                                         hsm_irqfd_shutdown()\n                                           list_del_init()\n                                           eventfd_ctx_remove_wait_queue()\n                                           eventfd_ctx_put()\n                                         kfree(irqfd)\n  hsm_irqfd_shutdown_work()\n    container_of(work, ..., shutdown)\n    irqfd->vm                  <-- use-after-free\n\nThe deassign path freed the irqfd while a shutdown work item was\nalready queued by EPOLLHUP (or vice versa), so the work item could\nresurrect a dangling pointer through container_of().\n\nSwitch to the lifetime model used by KVM irqfds:\n\n - Deassign/deinit only deactivate the irqfd: remove it from vm->irqfds\n   under irqfds_lock and queue the cleanup work.\n - hsm_irqfd_shutdown_work() becomes the sole owner that unhooks the\n   eventfd waitqueue entry, drops the eventfd reference and frees the\n   irqfd.\n - A new HSM_IRQFD_FLAG_SHUTDOWN bit guarded by test_and_set_bit()\n   ensures the cleanup work is queued at most once, no matter how many\n   of {EPOLLHUP, deassign, deinit} fire concurrently.  This is safe to\n   call from the waitqueue callback, which runs with wqh->lock held and\n   IRQs disabled and therefore cannot take irqfds_lock.\n - acrn_irqfd_deassign() flushes vm->irqfd_wq before returning so the\n   eventfd is fully detached on return.  acrn_irqfd_deinit() deactivates\n   every irqfd, flushes the workqueue and only then destroys it, so no\n   path can queue_work() onto a torn-down workqueue.\n - acrn_irqfd_assign() now installs the eventfd waitqueue entry and\n   publishes the irqfd to vm->irqfds under irqfds_lock, so the irqfd is\n   never visible to deassign/deinit before its waitqueue entry is in\n   place, and any EPOLLHUP that fires in the assign window queues\n   cleanup work that blocks on irqfds_lock until publication is done.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97478","source_modified_at":"2026-10-21T12:52:49.658Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"aa3b483ff1d71c50b33db154048dff9a8f08ac71","lessThan":"6e9e007ee1dfb54bc2d070550308077ec28dbaec","status":"affected","versionType":"git"},{"version":"aa3b483ff1d71c50b33db154048dff9a8f08ac71","lessThan":"0e1152f689847b9db2f05454775d34610c1424c2","status":"affected","versionType":"git"},{"version":"aa3b483ff1d71c50b33db154048dff9a8f08ac71","lessThan":"d8156aacfcabb81f52c20ef89094945434d08079","status":"affected","versionType":"git"},{"version":"aa3b483ff1d71c50b33db154048dff9a8f08ac71","lessThan":"666c7f9e07925aa0863348f960e09bb89f8f05a3","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97478","source_modified_at":"2026-10-21T12:52:49.658Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"5.12","status":"affected"},{"version":"0","lessThan":"5.12","status":"unaffected","versionType":"semver"},{"version":"6.6.160","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.114","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.53","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97478","source_modified_at":"2026-10-21T12:52:49.658Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"6e9e007ee1dfb54bc2d070550308077ec28dbaec","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97478","source_modified_at":"2026-10-21T12:52:49.658Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"0e1152f689847b9db2f05454775d34610c1424c2","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-97478","source_modified_at":"2026-10-21T12:52:49.658Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"666c7f9e07925aa0863348f960e09bb89f8f05a3","basis":"first unaffected version stated in the CVE record"}],"cvss":7.8,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00125,"percentile":0.02022,"score_date":"2026-10-23"},"published_at":"2026-09-24T16:04:20.263Z","modified_at":"2026-10-21T12:52:49.658Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-97478","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-21T12:52:49.658Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-97478","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/6e9e007ee1dfb54bc2d070550308077ec28dbaec"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/0e1152f689847b9db2f05454775d34610c1424c2"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/d8156aacfcabb81f52c20ef89094945434d08079"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/666c7f9e07925aa0863348f960e09bb89f8f05a3"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-21T12:52:49.658Z","content_hash":"559bf73e5fb3384756e9c68c182bacaa7dbfb515ff68abef275dd4240eedfb7a"}}