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 Cc: stable Cc: Sean Christopherson Cc: Paolo Bonzini Cc: Greg Kroah-Hartman --- Sean C. correctly pointed out that max_apic_id is inclusive, while array_index_nospec is not. Changes in v3: - Put the diff and the changes to the feedback in a single patch, instead of spreading it out over multiple emails. - Remove premature SoB. - Not sent as a In-Reply-To the previous version. Changes in v2: - Add one to the length argument of array_index_nospec, so it becomes inclusive with max_apic_id. --- arch/x86/kvm/lapic.c | 2 ++ arch/x86/kvm/x86.c | 7 +++++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 73418dc0ebb2..0725d2cae742 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -852,6 +852,8 @@ static int __pv_send_ipi(unsigned long *ipi_bitmap, struct kvm_apic_map *map, if (min > map->max_apic_id) return 0; + min = array_index_nospec(min, map->max_apic_id + 1); + for_each_set_bit(i, ipi_bitmap, min((u32)BITS_PER_LONG, (map->max_apic_id - min + 1))) { if (map->phys_map[min + i]) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 93636f77c42d..43b63f1d1594 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10051,8 +10051,11 @@ static void kvm_sched_yield(struct kvm_vcpu *vcpu, unsigned long dest_id) rcu_read_lock(); map = rcu_dereference(vcpu->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(); -- 2.50.1