From: Mark Rutland <mark.rutl...@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.rutl...@arm.com>
Cc: Christoffer Dall <christoffer.d...@arm.com>
Cc: Marc Zyngier <marc.zyng...@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
Signed-off-by: Marc Zyngier <marc.zyng...@arm.com>
Signed-off-by: Sasha Levin <alexander.le...@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;
}
--
2.17.1
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