Linux KVM ARM64 nested_mmus UAF under mmu_lock
CVE-2026-46317 Published on June 9, 2026
KVM: arm64: Reassign nested_mmus array behind mmu_lock
In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Reassign nested_mmus array behind mmu_lock
kvm->arch.nested_mmus[] is walked under kvm->mmu_lock, including from the
MMU notifier path (kvm_unmap_gfn_range() -> kvm_nested_s2_unmap()), which
can run at any time. kvm_vcpu_init_nested() reallocates the array and frees
the old buffer while holding only kvm->arch.config_lock, so such a walker
can reference the freed array.
Allocate the new array outside of mmu_lock, as the allocation can sleep.
Under the lock, copy the existing entries, fix up the back pointers and
reassign the array. Free the old buffer after dropping the lock, as
kvfree() can sleep as well.
Products Associated with CVE-2026-46317
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Affected Versions
Linux:- Version 4f128f8e1aaac189f83d0f828bcdb2986d8d2e51 and below 918450ad6010df6ecd2efde12a1409e011da22d6 is affected.
- Version 4f128f8e1aaac189f83d0f828bcdb2986d8d2e51 and below 4424dbcb06d68e34e51c019a5781a7dc00731971 is affected.
- Version 4f128f8e1aaac189f83d0f828bcdb2986d8d2e51 and below 70543358fa08e0f7cebc3447c3b70fe97ad7aaa8 is affected.
- Version 6.11 is affected.
- Before 6.11 is unaffected.
- Version 6.18.35, <= 6.18.* is unaffected.
- Version 7.0.12, <= 7.0.* is unaffected.
- Version 7.1-rc7, <= * is unaffected.