{"id":"CVE-2026-74568","revision":"910117705912414aa4c9a243d9731f02","records":[{"revision":"910117705912414aa4c9a243d9731f02","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-74568","aliases":[],"title":"KVM: arm64: vgic: Fix race between LPI release and re-registration","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: vgic: Fix race between LPI release and re-registration\n\nFix a potential race between decrementing an LPI's reference count and\nevicting that structure from the LPI xarray.\n\nLPI structures are maintained in the VGIC LPI xarray (dist->lpi_xa).\nWhen the reference count of an LPI structure drops to zero,\nvgic_release_lpi_locked() removes the structure from the xarray and\nfrees it under the xarray lock.\n\nHowever, the release of an LPI can race with a concurrent LPI\nre-registration with the same INTID via vgic_add_lpi() on another CPU,\nsince the reference count drop and the xarray eviction are not performed\nin a single atomic step. This can happen e.g. if the guest issues a\nDISCARD while the LPI is still referenced from a vCPU's active-pending\nlist (ap_list), and the same INTID is re-mapped via MAPTI.\n\nParticularly, vgic_release_lpi_locked() is called from two distinct\npaths: direct release via vgic_put_irq(), and deferred release via\nvgic_release_deleted_lpis(). During direct release, the issue can result\nin deleting a newly registered LPI from the xarray:\n\n CPU0 (Releasing LPI) CPU1 (Adding new LPI)\n ==================== =====================\n vgic_put_irq()\n __vgic_put_irq()\n refcount_dec_and_test()\n vgic_add_lpi()\n xa_lock_irqsave()\n old_irq = xa_load(.., intid)\n vgic_try_get_irq_ref(old_irq) == false\n new IRQ inserted --> __xa_store(.., intid, ..)\n xa_unlock_irqrestore()\n xa_lock_irqsave();\n vgic_release_lpi_locked()\n __xa_erase(.., irq->intid) <-- BUG: new IRQ is erased\n kfree_rcu(old_irq)\n\nDuring the deferred release path, the old IRQ can be leaked:\n\n CPU0 (Releasing LPI) CPU1 (Adding new LPI)\n ==================== =====================\n vgic_put_irq_norelease()\n __vgic_put_irq()\n refcount_dec_and_test()\n irq->pending_release = true\n vgic_add_lpi()\n xa_lock_irqsave()\n old_irq = xa_load(.., intid)\n vgic_try_get_irq_ref(oldirq) == false\n BUG: old IRQ overwritten --> __xa_store(.., intid, ..)\n xa_unlock_irqrestore()\n\n vgic_release_deleted_lpis()\n xa_lock_irqsave()\n xa_for_each() { .. } <-- old IRQ with pending_release = true\n is gone, so it cannot be released\n\nTo fix the direct release path, move the reference count drop inside\nthe xarray lock, making sure that vgic_add_lpi() never encounters the\nto-be-released LPI.\n\nIn the deferred release path, the refcount drop must happen under a raw\nspinlock, so the xarray lock cannot be grabbed, and the same solution\ndoes not work. Instead, update vgic_add_lpi(), so that if it evicts\nan LPI from the xarray, it takes on the responsibility of freeing it.\nConsequently, an LPI may now be freed concurrently after a deferred\nrelease drops the refcount, so accessing the pending_release field is no\nlonger safe from use-after-free. Delete all uses of the flag, and update\nvgic_release_deleted_lpis() to identify orphaned LPIs purely based on\ntheir refcount.","state":0,"publishedAt":"2026-08-15T12:28:08.859+00:00","modifiedAt":"2026-10-16T19:05:56.525+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"arch/arm64/kvm/vgic/vgic-its.c\",\n \"arch/arm64/kvm/vgic/vgic.c\",\n \"include/kvm/arm_vgic.h\"\n ],\n \"versions\": [\n {\n \"version\": \"3a08a6ca7c373198c84e2a8c025c395ee966ff8a\",\n \"lessThan\": \"f8e5715a37378ea1a140ee1162fa441e149c5142\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"3a08a6ca7c373198c84e2a8c025c395ee966ff8a\",\n \"lessThan\": \"292e80a159aa88635bf668a7212cfdf526b8bd52\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"3a08a6ca7c373198c84e2a8c025c395ee966ff8a\",\n \"lessThan\": \"cbfe2b24a1ea9de35032dbdd100fdc700f5be92d\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"arch/arm64/kvm/vgic/vgic-its.c\",\n \"arch/arm64/kvm/vgic/vgic.c\",\n \"include/kvm/arm_vgic.h\"\n ],\n \"versions\": [\n {\n \"version\": \"6.17\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"6.17\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.57\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1.8\",\n \"lessThanOrEqual\": \"7.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","score":9.3,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/f8e5715a37378ea1a140ee1162fa441e149c5142","https://git.kernel.org/stable/c/292e80a159aa88635bf668a7212cfdf526b8bd52","https://git.kernel.org/stable/c/cbfe2b24a1ea9de35032dbdd100fdc700f5be92d"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74568","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-74568","identifiers":["CVE-2026-74568"]},"retained":false,"historicalAffected":[]}],"coverage":[]}