kvm: Fix nonsense handling of compat ioctl

KVM_SET_SIGNAL_MASK passed a NULL argument leaves the on stack signal
sets uninitialized. It then passes them through to
kvm_vcpu_ioctl_set_sigmask.

We should be passing a NULL in this case not translated garbage.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 246852397e30..d617f69131d7 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1976,9 +1976,10 @@ static long kvm_vcpu_compat_ioctl(struct file *filp,
                         if (copy_from_user(&csigset, sigmask_arg->sigset,
                                            sizeof csigset))
                                 goto out;
-                }
-                sigset_from_compat(&sigset, &csigset);
-                r = kvm_vcpu_ioctl_set_sigmask(vcpu, &sigset);
+                        sigset_from_compat(&sigset, &csigset);
+                        r = kvm_vcpu_ioctl_set_sigmask(vcpu, &sigset);
+                } else
+                        r = kvm_vcpu_ioctl_set_sigmask(vcpu, NULL);
                 break;
         }
         default: