5.4-stable review patch. If anyone has any objections, please let me know.
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From: Thijs Raymakers thijs@raymakers.nl
commit c87bd4dd43a624109c3cc42d843138378a7f4548 upstream.
min and dest_id are guest-controlled indices. Using array_index_nospec() after the bounds checks clamps these values to mitigate speculative execution side-channels.
Signed-off-by: Thijs Raymakers thijs@raymakers.nl Cc: stable@vger.kernel.org Cc: Sean Christopherson seanjc@google.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Fixes: 715062970f37 ("KVM: X86: Implement PV sched yield hypercall") Fixes: bdf7ffc89922 ("KVM: LAPIC: Fix pv ipis out-of-bounds access") Fixes: 4180bf1b655a ("KVM: X86: Implement "send IPI" hypercall") Link: https://lore.kernel.org/r/20250804064405.4802-1-thijs@raymakers.nl Signed-off-by: Sean Christopherson seanjc@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/lapic.c | 3 +++ arch/x86/kvm/x86.c | 7 +++++-- 2 files changed, 8 insertions(+), 2 deletions(-)
--- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -589,6 +589,9 @@ int kvm_pv_send_ipi(struct kvm *kvm, uns
if (min > map->max_apic_id) goto out; + + min = array_index_nospec(min, map->max_apic_id + 1); + /* Bits above cluster_size are masked in the caller. */ for_each_set_bit(i, &ipi_bitmap_low, min((u32)BITS_PER_LONG, (map->max_apic_id - min + 1))) { --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7506,8 +7506,11 @@ static void kvm_sched_yield(struct kvm * rcu_read_lock(); map = rcu_dereference(kvm->arch.apic_map);
- if (likely(map) && dest_id <= map->max_apic_id && map->phys_map[dest_id]) - target = map->phys_map[dest_id]->vcpu; + if (likely(map) && dest_id <= map->max_apic_id) { + dest_id = array_index_nospec(dest_id, map->max_apic_id + 1); + if (map->phys_map[dest_id]) + target = map->phys_map[dest_id]->vcpu; + }
rcu_read_unlock();