Re: [PATCH 0/2] KVM: Fix a guest_memfd memslot UAF

[Sean Christopherson]

On Mon, 01 Dec 2025 18:03:32 -0800, Sean Christopherson wrote:
> Fix a UAF due to leaving a dangling guest_memfd memslot binding by
> disallowing clearing KVM_MEM_GUEST_MEMFD on a memslot.  The intent was
> that guest_memfd memslots would be immutable (could only be deleted),
> but somewhat ironically we missed the case where KVM_MEM_GUEST_MEMFD
> itself is the only flag that's toggled.
> 
> This is an ABI change, but I can't imagine anyone was relying on
> disappearing a guest_memfd memslot.
> 
> [...]

Applied to kvm-x86 fixes (I'm feeling lucky with the ABI change).

[1/2] KVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot
      https://github.com/kvm-x86/linux/commit/9935df5333aa
[2/2] KVM: Harden and prepare for modifying existing guest_memfd memslots
      https://github.com/kvm-x86/linux/commit/af62fe2494da

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https://github.com/kvm-x86/linux/tree/next