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

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

At the same time, sort the includes when adding <linux/nospec.h>.

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>
CVE-2017-5753

(backported from commit 41b87599c74300027f305d7b34368ec558978ff2)
[juergh: Adjusted context.]
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 96a498871fa0fb19bbbe84b4439c04e8d9642105..4332bef09228e49c2318e9d365bf4f26dc0c66bc 100644 (file)
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -14,11 +14,12 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/interrupt.h>
+#include <linux/irq.h>
 #include <linux/kvm.h>
 #include <linux/kvm_host.h>
 #include <linux/list_sort.h>
-#include <linux/interrupt.h>
-#include <linux/irq.h>
+#include <linux/nospec.h>
 
 #include "vgic.h"
 
@@ -105,12 +106,16 @@ struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
                              u32 intid)
 {
        /* SGIs and PPIs */
-       if (intid <= VGIC_MAX_PRIVATE)
+       if (intid <= VGIC_MAX_PRIVATE) {
+               intid = array_index_nospec(intid, VGIC_MAX_PRIVATE);
                return &vcpu->arch.vgic_cpu.private_irqs[intid];
+       }
 
        /* SPIs */
-       if (intid <= VGIC_MAX_SPI)
+       if (intid <= VGIC_MAX_SPI) {
+               intid = array_index_nospec(intid, VGIC_MAX_SPI);
                return &kvm->arch.vgic.spis[intid - VGIC_NR_PRIVATE_IRQS];
+       }
 
        /* LPIs */
        if (intid >= VGIC_MIN_LPI)