{"id":"CVE-2026-89960","title":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio-ap: fix stale pqap_hook pointer on error in vfio_ap_mdev_set_kvm()\n\nIn vfio_ap_mdev_set_kvm(), kvm->arch.crypto.pqap_hook is set to\n&matrix_mdev->pqap_hook be…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio-ap: fix stale pqap_hook pointer on error in vfio_ap_mdev_set_kvm()\n\nIn vfio_ap_mdev_set_kvm(), kvm->arch.crypto.pqap_hook is set to\n&matrix_mdev->pqap_hook be…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","vendor":"Linux","product":"Linux","affected":["Linux >= 86956e70761b3292156d668e87126844334dd71b < eb6cc898501a004c0fa8aab951351d9c959b91cc","Linux >= 86956e70761b3292156d668e87126844334dd71b < 6a180adafc2a8a5fbe815985c71b2201e93ab5e1","Linux >= 86956e70761b3292156d668e87126844334dd71b < fc069d00a0dbef40042fd681554d48dcd5a1d524","Linux >= 86956e70761b3292156d668e87126844334dd71b < 13bfc94eef389bd664ffc67b00184919902c938a","Linux >= 86956e70761b3292156d668e87126844334dd71b < 4400270ec0348d05dc0439d8f0130853ce7f9e20","Linux 5.15"],"published":"2026-09-16","updated":"2026-09-16","sourceUpdated":"2026-09-16T15:18:20.560","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-89960","references":[{"url":"https://git.kernel.org/stable/c/13bfc94eef389bd664ffc67b00184919902c938a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/4400270ec0348d05dc0439d8f0130853ce7f9e20","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6a180adafc2a8a5fbe815985c71b2201e93ab5e1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/eb6cc898501a004c0fa8aab951351d9c959b91cc","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fc069d00a0dbef40042fd681554d48dcd5a1d524","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-16T10:53:53.959Z","epss":0.00159,"epssPercentile":0.05462,"slug":"CVE-2026-89960","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio-ap: fix stale pqap_hook pointer on error in vfio_ap_mdev_set_kvm()\n\nIn vfio_ap_mdev_set_kvm(), kvm->arch.crypto.pqap_hook is set to\n&matrix_mdev->pqap_hook before the update locks are acquired and the\nmdev list is checked for a conflicting assignment. If another mdev is\nalready attached to the same KVM instance, the function returns -EPERM\nwithout restoring the hook pointer, leaving kvm->arch.crypto.pqap_hook\npointing at the failing matrix_mdev instead of the mdev that legitimately\nowns the KVM.\n\nSince matrix_mdev->kvm is never set on this error path,\nvfio_ap_mdev_unset_kvm() will not clean up the hook when matrix_mdev\nis later closed. If matrix_mdev is subsequently freed, any PQAP\ninstruction executed by the guest will dereference the stale pointer\nthrough pqap_hook_rwsem, resulting in a use-after-free.\n\nSince kvm->arch.crypto.pqap_hook is only set in the vfio_ap_mdev_set_kvm()\nfunction and is cleared in the vfio_ap_mdev_unset_kvm() function, a check\nfor 'kvm->arch.crypto.pqap_hook != NULL' is all that is needed to determine\nwhether it belongs to another mdev. This will alleviate the need to iterate\nthe matrix_dev->mdev_list list to see if the kvm object is assigned to\nanother mdev.This was introduced in v3 to alleviate the need to take the\nmdevs_lock while iterating the list; however, this did not prevent a\npotential race condition.\n\nThe pqap_hook_rwsem(write) is now performed inside\nget_update_locks_for_kvm(), which is updated to acquire\npqap_hook_rwsem(write) between kvm->lock and mdevs_lock. This ordering\nis consistent with the PQAP intercept path, which acquires pqap_hook_rwsem\nin read mode while srcu is held under vcpu->mutex, establishing the\ndependency: kvm->lock -> vcpu->mutex -> srcu -> pqap_hook_rwsem(read).\n\nThe pqap_hook_rwsem is now released inside the\nrelease_update_locks_for_kvm(), which is updated to release\npqap_hook_rwsem(write) between mdevs_lock and kvm->lock.\n\nAdditionally, kvm_put_kvm() in vfio_ap_mdev_unset_kvm() is moved\nafter release_update_locks_for_kvm(). Previously it was called while\nkvm->lock was held; if it were ever the last reference, kvm_destroy_vm()\nwould run under kvm->lock, which would deadlock.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":205107,"id":"CVE-2026-89960","ts":1789570705261,"field":"cvss","old":null,"new":"8.8"},{"seq":205106,"id":"CVE-2026-89960","ts":1789570705261,"field":"severity","old":"none","new":"high"}]}