4.16-stable review patch. If anyone has any objections, please let me know.
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From: Mark Rutland mark.rutland@arm.com
[ Upstream commit 5e1ca5e23b167987d5b6d8b08f2d5b7dd2d13f49 ]
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: Mark Rutland mark.rutland@arm.com Acked-by: Christoffer Dall christoffer.dall@arm.com Acked-by: Marc Zyngier marc.zyngier@arm.com Cc: kvmarm@lists.cs.columbia.edu Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- virt/kvm/arm/vgic/vgic-mmio-v2.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/virt/kvm/arm/vgic/vgic-mmio-v2.c +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c @@ -14,6 +14,8 @@ #include <linux/irqchip/arm-gic.h> #include <linux/kvm.h> #include <linux/kvm_host.h> +#include <linux/nospec.h> + #include <kvm/iodev.h> #include <kvm/arm_vgic.h>
@@ -324,6 +326,9 @@ static unsigned long vgic_mmio_read_apr(
if (n > vgic_v3_max_apr_idx(vcpu)) return 0; + + n = array_index_nospec(n, 4); + /* GICv3 only uses ICH_AP1Rn for memory mapped (GICv2) guests */ return vgicv3->vgic_ap1r[n]; }