| Message ID | 20180710180123.56461-3-mark.rutland@arm.com |
|---|---|
| State | Accepted |
| Commit | 6b8b9a48545e08345b8ff77c9fd51b1aebdbefb3 |
| Headers | show |
| Series | arm64: spectre-v1 write fixes (CVE-2018-3693) | expand |
diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c index ffc587bf4742..64e571cc02df 100644 --- 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 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; }
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 --- virt/kvm/arm/vgic/vgic-mmio-v2.c | 3 +++ 1 file changed, 3 insertions(+) -- 2.11.0