4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mark Rutland <mark.rutland@xxxxxxx> [ Upstream commit 6b8b9a48545e08345b8ff77c9fd51b1aebdbefb3 ] It's possible for userspace to control n. Sanitize n when using it as an array index, to inhibit the potential spectre-v1 write gadget. Note that while it appears that n must be bound to the interval [0,3] due to the way it is extracted from addr, we cannot guarantee that compiler transformations (and/or future refactoring) will ensure this is the case, and given this is a slow path it's better to always perform the masking. Found by smatch. Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> Cc: Christoffer Dall <christoffer.dall@xxxxxxx> Cc: Marc Zyngier <marc.zyngier@xxxxxxx> Cc: kvmarm@xxxxxxxxxxxxxxxxxxxxx Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- virt/kvm/arm/vgic/vgic-mmio-v2.c | 3 +++ 1 file changed, 3 insertions(+) --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c @@ -352,6 +352,9 @@ static void vgic_mmio_write_apr(struct k if (n > vgic_v3_max_apr_idx(vcpu)) return; + + n = array_index_nospec(n, 4); + /* GICv3 only uses ICH_AP1Rn for memory mapped (GICv2) guests */ vgicv3->vgic_ap1r[n] = val; }
