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authorMark Rutland <mark.rutland@arm.com>2018-07-10 19:01:23 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-09-26 08:38:02 +0200
commit737066efec608045559ce62abda4210962526349 (patch)
tree80a3d5b7f3883aa04493f6e3ea26320c4be866a1 /virt
parent3cb3868f98f53468160eb732d30ef29aaf046ae3 (diff)
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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 <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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 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;
}