KVM: Don't accept obviously wrong gsi values via KVM_IRQFD

We cannot add routes for gsi values >= KVM_MAX_IRQ_ROUTES -- see
kvm_set_irq_routing(). Hence, there is no sense in accepting them
via KVM_IRQFD. Prevent them from entering the system in the first
place.

Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index f2ac53ab8243..c608ab495282 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -565,6 +565,8 @@ kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
 {
         if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE))
                 return -EINVAL;
+        if (args->gsi >= KVM_MAX_IRQ_ROUTES)
+                return -EINVAL;
 
         if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
                 return kvm_irqfd_deassign(kvm, args);