# cveboard — Historical CVE brief

## Instructions for the operator's AI
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Fix information unknown; no fixed version is derived here. Missing information does not prove that no fix exists.
Exploitation unknown; this catalogue does not assess exploitation.

## Source facts (JSON-quoted data)
CNA source text (English)
id: "CVE-2026-98473"
idYear: 2026
status: "PUBLISHED"
publishedAt: "2026-10-18T15:15:35.479Z"
updatedAt: "2026-10-19T09:20:11.069Z"
importedAt: "2026-10-24T01:58:41.756Z"
snapshot: {"id":"cve_2026-10-24_midnight_baseline","at":"2026-10-24T00:00:00.000Z","source":"https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"}
url: "https://cveboard.org/cve/CVE-2026-98473"
json: "https://cveboard.org/cve/CVE-2026-98473.json"
sourceURL: "https://www.cve.org/CVERecord?id=CVE-2026-98473"
title: "s390/vfio-ap: fix KVM GISC and page leak when queue removed from host config"
summary: "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio-ap: fix KVM GISC and page leak when queue removed from host config\n\nThree related problems exist in the handling of KVM interrupt and page\nresources when a queue is removed from the host's AP configuration\nwhile assigned to a mediated device (mdev).\n\nProblem 1:\n~~~~~~~~~\nAP_RESPONSE_Q_NOT_AVAIL not handled in vfio_ap_mdev_reset_queue()\n\nWhen the AP bus removes a queue device whose adapter or domain has\nbeen removed from the host's AP configuration,\nvfio_ap_mdev_remove_queue() is called. If the queue is still in the\nhost's AP configuration at that point, it calls\nvfio_ap_mdev_reset_queue(), which issues a PQAP(ZAPQ). Since the\nadapter is already gone from the host configuration, ap_zapq() returns\nAP_RESPONSE_Q_NOT_AVAIL (0x01). This response code is not handled in\nvfio_ap_mdev_reset_queue()'s switch statement and falls through to\nthe default case, which issues a WARN but does not call\nvfio_ap_free_aqic_resources(). As a result, if IRQ handling was\nenabled for the queue by the guest, the KVM GISC registration and\nthe pinned guest page holding the notification indicator byte (NIB)\nare both leaked.\n\nThis is fixed by adding AP_RESPONSE_Q_NOT_AVAIL to the same case as\nAP_RESPONSE_DECONFIGURED and AP_RESPONSE_CHECKSTOPPED in\nvfio_ap_mdev_reset_queue(). Like those response codes, Q_NOT_AVAIL\nindicates the queue is not operational and no further reset attempts\nare possible; the correct action is to free the IRQ resources\nimmediately.\n\nProblem 2:\n~~~~~~~~~\n AP_RESPONSE_Q_NOT_AVAIL not handled in apq_status_check()\n\nIn vfio_ap_mdev_reset_queue(), there are four cases that indicate a queue\nreset has not yet completed, in which case apq_reset_check() is queued to\na work queue to verify completion of the reset operation. This function\nuses the PQAP(TAPQ) function to get the queue's status and calls\napq_status_check() to verify whether the reset has completed, failed or\nneeds to be executed again. As described in Problem #1 above,\napq_reset_check() does not specifically check for AP_RESPONSE_Q_NOT_AVAIL,\nthereby potentially leaking KVM GISC registration and the pinned guest page\nholding the NIB.\n\nThis is fixed by adding a case statement for AP_RESPONSE_Q_NOT_AVAIL to\napq_status_check() and returning -ENODEV for that case. The caller,\napq_reset_check() will then check for this return code and call\nvfio_ap_free_aqic_resources() to prevent the leak.\n\nProblem 3:\n~~~~~~~~~\nvfio_ap_free_aqic_resources() leaks saved_isc when kvm is NULL\n\nvfio_ap_free_aqic_resources() guards the call to\nkvm_s390_gisc_unregister() with:\n\n    if (q-\u003esaved_isc != VFIO_AP_ISC_INVALID &&\n        !WARN_ON(!(q-\u003ematrix_mdev && q-\u003ematrix_mdev-\u003ekvm)))\n\nIf matrix_mdev-\u003ekvm is NULL -- which can happen when\nvfio_ap_mdev_unset_kvm() has already run and cleared kvm before a\nsubsequent cleanup path reaches this function -- the WARN_ON fires\nand the entire block is skipped. This leaves q-\u003esaved_isc set to a\nnon-invalid value, creating a potential double-free on any subsequent\ncall to this function.\n\nWhen kvm is NULL the KVM guest is already torn down, so\nkvm_s390_gisc_unregister() need not and cannot be called; however,\nq-\u003esaved_isc must always be cleared. Fix this by separating the\nkvm_s390_gisc_unregister() call from the q-\u003esaved_isc reset. The\nWARN_ON now guards only the genuinely impossible case of matrix_mdev\nbeing NULL. A NULL kvm is handled gracefully by skipping only the\nunregister call, and q-\u003esaved_isc = VFIO_AP_ISC_INVALID is set\nunconditionally whenever saved_isc was not already invalid.\n\nAdditionally, add an else clause to the host-config check in\nvfio_ap_mdev_remove_queue() to call vfio_ap_free_aqic_resources()\ndirectly when the queue is not in the host's AP configuration. This\nserves as a backstop: when the AP bus fires the driver .remove\ncallback after an adapter is removed from the host config, the queue\nis by definition no longer addressable, so vfio_ap_mdev_reset_queue\n---truncated---"
affected: [{"versions":[{"version":"b9bd10c43456d16abd97b717446f51afb3b88411","status":"affected","versionType":"git","lessThan":"da69d3ac53490724eba0ade9deb4e539a6ae9034"},{"version":"b9bd10c43456d16abd97b717446f51afb3b88411","status":"affected","versionType":"git","lessThan":"cf441a0db681dfad5e89b015d6be11365159d7a9"},{"version":"b9bd10c43456d16abd97b717446f51afb3b88411","status":"affected","versionType":"git","lessThan":"3c3433657c82f200dae36c29e2b80681c81b85be"},{"version":"b9bd10c43456d16abd97b717446f51afb3b88411","status":"affected","versionType":"git","lessThan":"65e05ec252a9b79e75930d3c4dd42d8877db04c5"},{"version":"582014b08cb83383cdd61f052cd81e8aa5023696","status":"affected","versionType":"git"},{"version":"7abe1494896c052d5dcf4ba910656777aff72fbb","status":"affected","versionType":"git"},{"version":"6.6.15","status":"affected","versionType":"semver","lessThan":"6.7"},{"version":"6.7.3","status":"affected","versionType":"semver","lessThan":"6.8"}],"vendor":"Linux","product":"Linux","defaultStatus":"unaffected"},{"versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","versionType":"semver","lessThan":"6.8"},{"version":"6.12.112","status":"unaffected","versionType":"semver","lessThanOrEqual":"6.12.*"},{"version":"6.18.55","status":"unaffected","versionType":"semver","lessThanOrEqual":"6.18.*"},{"version":"7.2.9","status":"unaffected","versionType":"semver","lessThanOrEqual":"7.2.*"},{"version":"7.3","status":"unaffected","versionType":"original_commit_for_fix","lessThanOrEqual":"*"}],"vendor":"Linux","product":"Linux","defaultStatus":"affected"}]

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