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authorMark Rutland <mark.rutland@arm.com>2018-07-10 19:01:23 +0100
committerMarc Zyngier <marc.zyngier@arm.com>2018-07-24 13:53:54 +0100
commit6b8b9a48545e08345b8ff77c9fd51b1aebdbefb3 (patch)
tree03edc816580eadf5c76be597c86eeec9a9aea11a /virt
parentb0960b9569db6b2fe8a75967d47b9dcdeb44016b (diff)
downloadlinux-aarch64-6b8b9a48545e08345b8ff77c9fd51b1aebdbefb3.tar.gz
KVM: arm/arm64: vgic: Fix possible spectre-v1 write in vgic_mmio_write_apr()
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>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/arm/vgic/vgic-mmio-v2.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
index 26654f4140ed..738b65d2d0e7 100644
--- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
+++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
@@ -399,6 +399,9 @@ 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;
}