From: Mark Rutland mark.rutland@arm.com
[ 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@arm.com Cc: Christoffer Dall christoffer.dall@arm.com Cc: Marc Zyngier marc.zyngier@arm.com Cc: kvmarm@lists.cs.columbia.edu Signed-off-by: Marc Zyngier marc.zyngier@arm.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- virt/kvm/arm/vgic/vgic-mmio-v2.c | 3 +++ 1 file changed, 3 insertions(+)
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; }