Commit 5e1ca5e2 authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon

KVM: arm/arm64: vgic: fix possible spectre-v1 in vgic_mmio_read_apr()

It's possible for userspace to control n. Sanitize n when using it as an
array index.

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: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarChristoffer Dall <christoffer.dall@arm.com>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 41b87599
...@@ -14,6 +14,8 @@ ...@@ -14,6 +14,8 @@
#include <linux/irqchip/arm-gic.h> #include <linux/irqchip/arm-gic.h>
#include <linux/kvm.h> #include <linux/kvm.h>
#include <linux/kvm_host.h> #include <linux/kvm_host.h>
#include <linux/nospec.h>
#include <kvm/iodev.h> #include <kvm/iodev.h>
#include <kvm/arm_vgic.h> #include <kvm/arm_vgic.h>
...@@ -324,6 +326,9 @@ static unsigned long vgic_mmio_read_apr(struct kvm_vcpu *vcpu, ...@@ -324,6 +326,9 @@ static unsigned long vgic_mmio_read_apr(struct kvm_vcpu *vcpu,
if (n > vgic_v3_max_apr_idx(vcpu)) if (n > vgic_v3_max_apr_idx(vcpu))
return 0; return 0;
n = array_index_nospec(n, 4);
/* GICv3 only uses ICH_AP1Rn for memory mapped (GICv2) guests */ /* GICv3 only uses ICH_AP1Rn for memory mapped (GICv2) guests */
return vgicv3->vgic_ap1r[n]; return vgicv3->vgic_ap1r[n];
} }
......
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