Try to handle possible vm_register() failures and return an error back

to the caller instead of most probably crashing because of a NULL pointer
access. This fixes also another -Wunused-but-set-variable warning.
OK benno@ dv@

diff --git a/usr.sbin/vmd/vmm.c b/usr.sbin/vmd/vmm.c
index 6a2d55d..eb75b4c 100644 (file)
--- a/usr.sbin/vmd/vmm.c
+++ b/usr.sbin/vmd/vmm.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: vmm.c,v 1.102 2021/11/29 05:17:35 deraadt Exp $       */
+/*     $OpenBSD: vmm.c,v 1.103 2022/01/04 15:25:05 claudio Exp $       */
 
 /*
  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
@@ -102,7 +102,7 @@ int
 vmm_dispatch_parent(int fd, struct privsep_proc *p, struct imsg *imsg)
 {
        struct privsep          *ps = p->p_ps;
-       int                      res = 0, cmd = 0, verbose, ret;
+       int                      res = 0, cmd = 0, verbose;
        struct vmd_vm           *vm = NULL;
        struct vm_terminate_params vtp;
        struct vmop_id           vid;
@@ -278,8 +278,12 @@ vmm_dispatch_parent(int fd, struct privsep_proc *p, struct imsg *imsg)
        case IMSG_VMDOP_RECEIVE_VM_REQUEST:
                IMSG_SIZE_CHECK(imsg, &vmc);
                memcpy(&vmc, imsg->data, sizeof(vmc));
-               ret = vm_register(ps, &vmc, &vm,
-                   imsg->hdr.peerid, vmc.vmc_owner.uid);
+               if (vm_register(ps, &vmc, &vm,
+                   imsg->hdr.peerid, vmc.vmc_owner.uid) != 0) {
+                       res = errno;
+                       cmd = IMSG_VMDOP_START_VM_RESPONSE;
+                       break;
+               }
                vm->vm_tty = imsg->fd;
                vm->vm_state |= VM_STATE_RECEIVED;
                vm->vm_state |= VM_STATE_PAUSED;
@@ -328,6 +332,7 @@ vmm_dispatch_parent(int fd, struct privsep_proc *p, struct imsg *imsg)
                }
                if (id == 0)
                        id = imsg->hdr.peerid;
+               /* FALLTHROUGH */
        case IMSG_VMDOP_PAUSE_VM_RESPONSE:
        case IMSG_VMDOP_UNPAUSE_VM_RESPONSE:
        case IMSG_VMDOP_TERMINATE_VM_RESPONSE: