vmm(4): grab kernel lock before vmspace init

We need the kernel lock before calling some uvm functions. Fixes a
panic reported by syzbot.

Reported-by: syzbot+dd7a70eaf794705db27e@syzkaller.appspotmail.com
ok mlarkin@

diff --git a/sys/arch/amd64/amd64/vmm.c b/sys/arch/amd64/amd64/vmm.c
index ffe06fb..c04a1f0 100644 (file)
--- a/sys/arch/amd64/amd64/vmm.c
+++ b/sys/arch/amd64/amd64/vmm.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: vmm.c,v 1.289 2021/09/02 07:19:53 dv Exp $    */
+/*     $OpenBSD: vmm.c,v 1.290 2021/09/03 11:47:05 dv Exp $    */
 /*
  * Copyright (c) 2014 Mike Larkin <mlarkin@openbsd.org>
  *
@@ -1685,14 +1685,20 @@ vm_impl_init_svm(struct vm *vm, struct proc *p)
 int
 vm_impl_init(struct vm *vm, struct proc *p)
 {
+       int ret;
+
+       KERNEL_LOCK();
        if (vmm_softc->mode == VMM_MODE_VMX ||
            vmm_softc->mode == VMM_MODE_EPT)
-               return vm_impl_init_vmx(vm, p);
+               ret = vm_impl_init_vmx(vm, p);
        else if (vmm_softc->mode == VMM_MODE_SVM ||
                 vmm_softc->mode == VMM_MODE_RVI)
-               return vm_impl_init_svm(vm, p);
+               ret = vm_impl_init_svm(vm, p);
        else
                panic("%s: unknown vmm mode: %d", __func__, vmm_softc->mode);
+       KERNEL_UNLOCK();
+
+       return (ret);
 }
 
 /*