From 737066efec608045559ce62abda4210962526349 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Tue, 10 Jul 2018 19:01:23 +0100 Subject: KVM: arm/arm64: vgic: Fix possible spectre-v1 write in vgic_mmio_write_apr() [ 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 Cc: Christoffer Dall Cc: Marc Zyngier Cc: kvmarm@lists.cs.columbia.edu Signed-off-by: Marc Zyngier Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- virt/kvm/arm/vgic/vgic-mmio-v2.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'virt') diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c index af003268bf3e..7ea5928244fa 100644 --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c @@ -348,6 +348,9 @@ static void vgic_mmio_write_apr(struct kvm_vcpu *vcpu, 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; } -- cgit v1.2.3