Re: [PATCH] KVM: VMX: Add array_index_nospec() to evmcs_field_offset()
From: Sean Christopherson
Date: Fri Oct 23 2026 - 21:17:45 EST
On Fri, Oct 23, 2026, Amirmohammad Eftekhar wrote:
> From: Amirmohammad Eftekhar <amirmohammad.eftekhar@xxxxxxxx>
>
> evmcs_field_offset() bounds-checks the guest-supplied field index against
> nr_evmcs_1_fields and then indexes vmcs_field_to_evmcs_1[] with it, but,
> unlike its vmcs12 counterpart get_vmcs12_field_offset(), it does not clamp
> the index with array_index_nospec() after the check. The field index is
> derived from a guest-supplied VMCS field encoding on the enlightened
> VMREAD/VMWRITE path, so the array access can be performed speculatively
> past the bounds check (Spectre v1), disclosing memory adjacent to
> vmcs_field_to_evmcs_1[].
>
> Clamp the index with array_index_nospec() immediately after the bounds
> check, mirroring get_vmcs12_field_offset().
>
> Signed-off-by: Amirmohammad Eftekhar <amirmohammad.eftekhar@xxxxxxxx>
> ---
You already posted this exact patch[*], and at a glance several of the bug reports
appear to be duplicates as well. Please stop spamming duplicates. If you have
questions about the flow and/or timing of patches, e.g. since we're in a merge
window, then Documentation/process/maintainer-kvm-x86.rst is your friend.
[*] https://lore.kernel.org/all/20261017093016.32348-3-amirmohammad.eftekhar@xxxxxxxx