{"id":"CVE-2026-98467","title":"KVM: arm64: nv: Fix null ptr deref on nested wp/unmap, teardown race","summary":"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…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 7270cc9157f474dfc46750a34c9d7defc686b2eb < 970de111c087488e53cadf5480b94e0f695db985","Linux >= 7270cc9157f474dfc46750a34c9d7defc686b2eb < 3cefc1ab511fad6a0f708e7a4aee9f91346e9457","Linux >= 7270cc9157f474dfc46750a34c9d7defc686b2eb < 4c74e233cdedd11592775fae2a6243e67ca3f891","Linux 6.16"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:15:19.294Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98467","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"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T15:45:12.300Z","slug":"CVE-2026-98467","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 7270cc9157f474dfc46750a34c9d7defc686b2eb < 970de111c087488e53cadf5480b94e0f695db985`\n- `Linux >= 7270cc9157f474dfc46750a34c9d7defc686b2eb < 3cefc1ab511fad6a0f708e7a4aee9f91346e9457`\n- `Linux >= 7270cc9157f474dfc46750a34c9d7defc686b2eb < 4c74e233cdedd11592775fae2a6243e67ca3f891`\n- `Linux 6.16`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}