[libvirt] [PATCH] qemudDomainSetVcpus: avoid NULL-deref

[Jim Meyering]

Here's a patch for a coverity-spotted bug:

>From 12160fa54bc948e5de3fecff6a9552995e9595b0 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering at redhat.com>
Date: Fri, 14 May 2010 12:38:43 +0200
Subject: [PATCH] qemudDomainSetVcpus: avoid NULL-deref

* src/qemu/qemu_driver.c (qemudDomainSetVcpus): Avoid NULL-deref
upon unknown UUID.  Call qemuDomainObjBeginJob(vm) only after
ensuring that vm != NULL, not before.  This potential NULL-deref
was introduced by commit 2c555d87b0041e0d1ec4742386d2161d1b2f0600.
---
 src/qemu/qemu_driver.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index bb1079e..cbddb96 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -5410,9 +5410,6 @@ static int qemudDomainSetVcpus(virDomainPtr dom, unsigned int nvcpus) {
     vm = virDomainFindByUUID(&driver->domains, dom->uuid);
     qemuDriverUnlock(driver);

-    if (qemuDomainObjBeginJob(vm) < 0)
-        goto cleanup;
-
     if (!vm) {
         char uuidstr[VIR_UUID_STRING_BUFLEN];
         virUUIDFormat(dom->uuid, uuidstr);
@@ -5421,6 +5418,9 @@ static int qemudDomainSetVcpus(virDomainPtr dom, unsigned int nvcpus) {
         goto endjob;
     }

+    if (qemuDomainObjBeginJob(vm) < 0)
+        goto cleanup;
+
     if (!virDomainObjIsActive(vm)) {
         qemuReportError(VIR_ERR_OPERATION_INVALID,
                          "%s", _("domain is not running"));
--
1.7.1.460.gf3c4c