{"id":"CVE-2026-98467","state":"PUBLISHED","title":"KVM: arm64: nv: Fix null ptr deref on nested wp/unmap, teardown race","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: nv: Fix null ptr deref on nested wp/unmap, teardown race\n\nCommit 7270cc9157f4 (\"KVM: arm64: nv: Handle VNCR_EL2 invalidation from MMU\nnotifiers\") introduced VNCR_EL2 invalidation in both kvm_nested_s2_unmap()\nand kvm_nested_s2_wp().\n\nHowever at the point of this being performed concurrent stage 2 teardown of\na nested guest can cause kvm->arch.mmu.pgt to be set to NULL.\n\nThis happens in kvm_flush_shadow_all() -> kvm_arch_flush_shadow_all() ->\nkvm_free_stage2_pgd() and is performed under the kvm->mmu_lock.\n\nCommit ec14c272408a (\"KVM: arm64: nv: Unmap/flush shadow stage 2 page\ntables\") introduced the teardown of the entire nested MMU range, which then\ninvokes stage2_apply_range() with resched=true:\n\nmmu_notifier_invalidate_range_start()\n  -> ... -> kvm_mmu_notifier_invalidate_range_start()\n    -> kvm_mmu_unmap_gfn_range()\n      -> kvm_unmap_gfn_range()\n        -> kvm_nested_s2_unmap()\n          -> kvm_stage2_unmap_range()\n            -> __unmap_stage2_range()\n                -> stage2_apply_range()\n\nThis means that stage2_apply_range() can drop the kvm->mmu_lock and thus\nconcurrent progress can be made in lockstep with\nkvm_arch_flush_shadow_all().\n\nIf kvm_arch_flush_shadow_all() advances ahead of stage2_apply_range() and\ncompletes its operation it guarantees a NULL pointer deref.\n\nSince kvm_free_stage2_pgd() is performed under the kvm->mmu_lock this will\neither be observed NULL or not and serialised against\nkvm_free_stage2_pgd().\n\nResolve the issue by abstracting the invalidation to a new function,\nkvm_invalidate_vncr_ipa_all(), and check that the pgt is non-NULL before\ndereferencing it.","publishedAt":"2026-10-18T15:15:19.294Z","updatedAt":"2026-10-19T09:20:05.363Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7270cc9157f474dfc46750a34c9d7defc686b2eb","status":"affected","lessThan":"970de111c087488e53cadf5480b94e0f695db985","versionType":"git"},{"version":"7270cc9157f474dfc46750a34c9d7defc686b2eb","status":"affected","lessThan":"3cefc1ab511fad6a0f708e7a4aee9f91346e9457","versionType":"git"},{"version":"7270cc9157f474dfc46750a34c9d7defc686b2eb","status":"affected","lessThan":"4c74e233cdedd11592775fae2a6243e67ca3f891","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kvm/nested.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.16","versionType":"semver"},{"version":"6.18.55","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.9","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kvm/nested.c"]}],"references":["https://git.kernel.org/stable/c/970de111c087488e53cadf5480b94e0f695db985","https://git.kernel.org/stable/c/3cefc1ab511fad6a0f708e7a4aee9f91346e9457","https://git.kernel.org/stable/c/4c74e233cdedd11592775fae2a6243e67ca3f891"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98467.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98467","state":"PUBLISHED","datePublished":"2026-10-18T15:15:19.294Z","dateUpdated":"2026-10-19T09:20:05.363Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.351Z"},"containers":{"cna":{"title":"KVM: arm64: nv: Fix null ptr deref on nested wp/unmap, teardown race","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: nv: Fix null ptr deref on nested wp/unmap, teardown race\n\nCommit 7270cc9157f4 (\"KVM: arm64: nv: Handle VNCR_EL2 invalidation from MMU\nnotifiers\") introduced VNCR_EL2 invalidation in both kvm_nested_s2_unmap()\nand kvm_nested_s2_wp().\n\nHowever at the point of this being performed concurrent stage 2 teardown of\na nested guest can cause kvm->arch.mmu.pgt to be set to NULL.\n\nThis happens in kvm_flush_shadow_all() -> kvm_arch_flush_shadow_all() ->\nkvm_free_stage2_pgd() and is performed under the kvm->mmu_lock.\n\nCommit ec14c272408a (\"KVM: arm64: nv: Unmap/flush shadow stage 2 page\ntables\") introduced the teardown of the entire nested MMU range, which then\ninvokes stage2_apply_range() with resched=true:\n\nmmu_notifier_invalidate_range_start()\n  -> ... -> kvm_mmu_notifier_invalidate_range_start()\n    -> kvm_mmu_unmap_gfn_range()\n      -> kvm_unmap_gfn_range()\n        -> kvm_nested_s2_unmap()\n          -> kvm_stage2_unmap_range()\n            -> __unmap_stage2_range()\n                -> stage2_apply_range()\n\nThis means that stage2_apply_range() can drop the kvm->mmu_lock and thus\nconcurrent progress can be made in lockstep with\nkvm_arch_flush_shadow_all().\n\nIf kvm_arch_flush_shadow_all() advances ahead of stage2_apply_range() and\ncompletes its operation it guarantees a NULL pointer deref.\n\nSince kvm_free_stage2_pgd() is performed under the kvm->mmu_lock this will\neither be observed NULL or not and serialised against\nkvm_free_stage2_pgd().\n\nResolve the issue by abstracting the invalidation to a new function,\nkvm_invalidate_vncr_ipa_all(), and check that the pgt is non-NULL before\ndereferencing it."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7270cc9157f474dfc46750a34c9d7defc686b2eb","status":"affected","lessThan":"970de111c087488e53cadf5480b94e0f695db985","versionType":"git"},{"version":"7270cc9157f474dfc46750a34c9d7defc686b2eb","status":"affected","lessThan":"3cefc1ab511fad6a0f708e7a4aee9f91346e9457","versionType":"git"},{"version":"7270cc9157f474dfc46750a34c9d7defc686b2eb","status":"affected","lessThan":"4c74e233cdedd11592775fae2a6243e67ca3f891","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kvm/nested.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.16","versionType":"semver"},{"version":"6.18.55","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.9","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kvm/nested.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/970de111c087488e53cadf5480b94e0f695db985"},{"url":"https://git.kernel.org/stable/c/3cefc1ab511fad6a0f708e7a4aee9f91346e9457"},{"url":"https://git.kernel.org/stable/c/4c74e233cdedd11592775fae2a6243e67ca3f891"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:20:05.363Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"6.18.55"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"7.2.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}