{"api_version":"1","generated_at":"2026-09-11T04:14:34+00:00","cve":"CVE-2026-80895","urls":{"html":"https://cve.report/CVE-2026-80895","api":"https://cve.report/api/cve/CVE-2026-80895.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-80895","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-80895"},"summary":{"title":"mshv: Order pt_vp_array publish against irqfd assertion path","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmshv: Order pt_vp_array publish against irqfd assertion path\n\nmshv_partition_ioctl_create_vp() initialises a VP struct (allocations,\nmutex_init, init_waitqueue_head, page mappings) and then publishes the\npointer into partition->pt_vp_array.  Several ISR paths read this array\nlocklessly: the intercept ISR, the two scheduler ISRs, and\nmshv_try_assert_irq_fast() on the irqfd fast path.\n\nOf these, only mshv_try_assert_irq_fast() can structurally race the\npublish.  It runs from an eventfd waker without holding pt_mutex, and\nMSHV_IRQFD does not require the target lapic_apic_id (== vp_index) to\nrefer to an existing VP at registration time.  A user can therefore\nregister an irqfd targeting a yet-to-be-created VP, then trigger\nmshv_try_assert_irq_fast() concurrently with MSHV_CREATE_VP for the\nsame index.  On weakly-ordered architectures the reader can observe a\nnon-NULL pointer in pt_vp_array before the initialising stores to the\nVP struct become visible, leading to use of partially-initialised\nfields (e.g. vp_register_page).\n\nThe other ISR readers cannot reach this race: the hypervisor will not\ngenerate intercept or scheduler messages for a VP that has never been\ntold to run, and the user can only call MSHV_RUN_VP on the VP fd\nreturned by MSHV_CREATE_VP, which by construction is returned after\nthe publish.  Leave those readers as plain loads.\n\nUse smp_store_release() in mshv_partition_ioctl_create_vp() to publish\nthe pointer, and pair it with smp_load_acquire() in\nmshv_try_assert_irq_fast().  On x86 these compile to plain accesses\nunder TSO; on ARM64 they emit one-instruction acquire/release barriers,\nacceptable on this fast path.\n\nThe destroy-side path (destroy_partition() clearing pt_vp_array[i] to\nNULL after kfree(vp)) has a separate ordering and lifetime concern\nthat is out of scope here.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-04 18:17:57","updated_at":"2026-09-04 18:17:57"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/062aa5dcc49a9ad96726a80c2a0ab0a1233bc2b9","name":"https://git.kernel.org/stable/c/062aa5dcc49a9ad96726a80c2a0ab0a1233bc2b9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/eba2bf5daa7933f94c53ebbbf0f567d4274716df","name":"https://git.kernel.org/stable/c/eba2bf5daa7933f94c53ebbbf0f567d4274716df","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b098dc869219c15dc49bf9cf63fb5fc1481d3373","name":"https://git.kernel.org/stable/c/b098dc869219c15dc49bf9cf63fb5fc1481d3373","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-80895","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80895","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 621191d709b14882270dfd8ea5d7d6cdfebe2c35 062aa5dcc49a9ad96726a80c2a0ab0a1233bc2b9 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 621191d709b14882270dfd8ea5d7d6cdfebe2c35 eba2bf5daa7933f94c53ebbbf0f567d4274716df git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 621191d709b14882270dfd8ea5d7d6cdfebe2c35 b098dc869219c15dc49bf9cf63fb5fc1481d3373 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.15","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.44 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.8 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"80895","cve":"CVE-2026-80895","epss":"0.001660000","percentile":"0.061770000","score_date":"2026-09-07","updated_at":"2026-09-08 00:05:26"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/hv/mshv_eventfd.c","drivers/hv/mshv_root_main.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"062aa5dcc49a9ad96726a80c2a0ab0a1233bc2b9","status":"affected","version":"621191d709b14882270dfd8ea5d7d6cdfebe2c35","versionType":"git"},{"lessThan":"eba2bf5daa7933f94c53ebbbf0f567d4274716df","status":"affected","version":"621191d709b14882270dfd8ea5d7d6cdfebe2c35","versionType":"git"},{"lessThan":"b098dc869219c15dc49bf9cf63fb5fc1481d3373","status":"affected","version":"621191d709b14882270dfd8ea5d7d6cdfebe2c35","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/hv/mshv_eventfd.c","drivers/hv/mshv_root_main.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.15"},{"lessThan":"6.15","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.44","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.8","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.44","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.8","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"6.15","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmshv: Order pt_vp_array publish against irqfd assertion path\n\nmshv_partition_ioctl_create_vp() initialises a VP struct (allocations,\nmutex_init, init_waitqueue_head, page mappings) and then publishes the\npointer into partition->pt_vp_array.  Several ISR paths read this array\nlocklessly: the intercept ISR, the two scheduler ISRs, and\nmshv_try_assert_irq_fast() on the irqfd fast path.\n\nOf these, only mshv_try_assert_irq_fast() can structurally race the\npublish.  It runs from an eventfd waker without holding pt_mutex, and\nMSHV_IRQFD does not require the target lapic_apic_id (== vp_index) to\nrefer to an existing VP at registration time.  A user can therefore\nregister an irqfd targeting a yet-to-be-created VP, then trigger\nmshv_try_assert_irq_fast() concurrently with MSHV_CREATE_VP for the\nsame index.  On weakly-ordered architectures the reader can observe a\nnon-NULL pointer in pt_vp_array before the initialising stores to the\nVP struct become visible, leading to use of partially-initialised\nfields (e.g. vp_register_page).\n\nThe other ISR readers cannot reach this race: the hypervisor will not\ngenerate intercept or scheduler messages for a VP that has never been\ntold to run, and the user can only call MSHV_RUN_VP on the VP fd\nreturned by MSHV_CREATE_VP, which by construction is returned after\nthe publish.  Leave those readers as plain loads.\n\nUse smp_store_release() in mshv_partition_ioctl_create_vp() to publish\nthe pointer, and pair it with smp_load_acquire() in\nmshv_try_assert_irq_fast().  On x86 these compile to plain accesses\nunder TSO; on ARM64 they emit one-instruction acquire/release barriers,\nacceptable on this fast path.\n\nThe destroy-side path (destroy_partition() clearing pt_vp_array[i] to\nNULL after kfree(vp)) has a separate ordering and lifetime concern\nthat is out of scope here."}],"providerMetadata":{"dateUpdated":"2026-09-04T17:11:10.880Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/062aa5dcc49a9ad96726a80c2a0ab0a1233bc2b9"},{"url":"https://git.kernel.org/stable/c/eba2bf5daa7933f94c53ebbbf0f567d4274716df"},{"url":"https://git.kernel.org/stable/c/b098dc869219c15dc49bf9cf63fb5fc1481d3373"}],"title":"mshv: Order pt_vp_array publish against irqfd assertion path","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-80895","datePublished":"2026-09-04T17:11:10.880Z","dateReserved":"2026-08-26T14:34:25.800Z","dateUpdated":"2026-09-04T17:11:10.880Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-04 18:17:57","lastModifiedDate":"2026-09-04 18:17:57","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"80895","Ordinal":"1","Title":"mshv: Order pt_vp_array publish against irqfd assertion path","CVE":"CVE-2026-80895","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"80895","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nmshv: Order pt_vp_array publish against irqfd assertion path\n\nmshv_partition_ioctl_create_vp() initialises a VP struct (allocations,\nmutex_init, init_waitqueue_head, page mappings) and then publishes the\npointer into partition->pt_vp_array.  Several ISR paths read this array\nlocklessly: the intercept ISR, the two scheduler ISRs, and\nmshv_try_assert_irq_fast() on the irqfd fast path.\n\nOf these, only mshv_try_assert_irq_fast() can structurally race the\npublish.  It runs from an eventfd waker without holding pt_mutex, and\nMSHV_IRQFD does not require the target lapic_apic_id (== vp_index) to\nrefer to an existing VP at registration time.  A user can therefore\nregister an irqfd targeting a yet-to-be-created VP, then trigger\nmshv_try_assert_irq_fast() concurrently with MSHV_CREATE_VP for the\nsame index.  On weakly-ordered architectures the reader can observe a\nnon-NULL pointer in pt_vp_array before the initialising stores to the\nVP struct become visible, leading to use of partially-initialised\nfields (e.g. vp_register_page).\n\nThe other ISR readers cannot reach this race: the hypervisor will not\ngenerate intercept or scheduler messages for a VP that has never been\ntold to run, and the user can only call MSHV_RUN_VP on the VP fd\nreturned by MSHV_CREATE_VP, which by construction is returned after\nthe publish.  Leave those readers as plain loads.\n\nUse smp_store_release() in mshv_partition_ioctl_create_vp() to publish\nthe pointer, and pair it with smp_load_acquire() in\nmshv_try_assert_irq_fast().  On x86 these compile to plain accesses\nunder TSO; on ARM64 they emit one-instruction acquire/release barriers,\nacceptable on this fast path.\n\nThe destroy-side path (destroy_partition() clearing pt_vp_array[i] to\nNULL after kfree(vp)) has a separate ordering and lifetime concern\nthat is out of scope here.","Type":"Description","Title":"mshv: Order pt_vp_array publish against irqfd assertion path"}]}}}