vbox: fix SEGV during dumpxml of a serial port

commit 77a12987 changed the "virDomainChrSourceDef source" inside
virDomainChrDef to "virDomainChrSourceDefPtr source", and started
allocating source inside virDomainChrDefNew(), but vboxDumpSerial()
was allocating a virDomainChrDef with a simple VIR_ALLOC() (i.e. never
calling virDomainChrDefNew()), so source was never initialized,
leading to a SEGV any time a serial port was present. The same problem
was created in vboxDumpParallel().

This patch changes vboxDumpSerial() and vboxDumpParallel() to use
virDomainChrDefNew() instead of VIR_ALLOC(), and changes both of those
functions to return an error if virDomainChrDef() (or any other
allocation) fails.

This resolves: https://bugzilla.redhat.com/1536649

(cherry picked from commit 9c27e464)

src/vbox/vbox_common.c

@@ -3614,7 +3614,7 @@ vboxDumpAudio(virDomainDefPtr def, vboxDriverPtr data ATTRIBUTE_UNUSED,
     }
 }
 
-static void
+static int
 vboxDumpSerial(virDomainDefPtr def, vboxDriverPtr data, IMachine *machine, PRUint32 serialPortCount)
 {
     PRUint32 serialPortIncCount = 0;
@@ -3638,9 +3638,15 @@ vboxDumpSerial(virDomainDefPtr def, vboxDriverPtr data, IMachine *machine, PRUin
     }
 
     /* Allocate memory for the serial ports which are enabled */
-    if ((def->nserials > 0) && (VIR_ALLOC_N(def->serials, def->nserials) >= 0)) {
-        for (i = 0; i < def->nserials; i++)
-            ignore_value(VIR_ALLOC(def->serials[i]));
+    if (def->nserials > 0) {
+        if (VIR_ALLOC_N(def->serials, def->nserials) < 0)
+            return -1;
+
+        for (i = 0; i < def->nserials; i++) {
+            def->serials[i] = virDomainChrDefNew(NULL);
+            if (!def->serials[i])
+                return -1;
+        }
     }
 
     /* Now get the details about the serial ports here */
@@ -3688,7 +3694,8 @@ vboxDumpSerial(virDomainDefPtr def, vboxDriverPtr data, IMachine *machine, PRUin
 
                 if (pathUtf16) {
                     VBOX_UTF16_TO_UTF8(pathUtf16, &path);
-                    ignore_value(VIR_STRDUP(def->serials[serialPortIncCount]->source->data.file.path, path));
+                    if (VIR_STRDUP(def->serials[serialPortIncCount]->source->data.file.path, path) < 0)
+                        return -1;
                 }
 
                 serialPortIncCount++;
@@ -3700,9 +3707,10 @@ vboxDumpSerial(virDomainDefPtr def, vboxDriverPtr data, IMachine *machine, PRUin
             VBOX_RELEASE(serialPort);
         }
     }
+    return 0;
 }
 
-static void
+static int
 vboxDumpParallel(virDomainDefPtr def, vboxDriverPtr data, IMachine *machine, PRUint32 parallelPortCount)
 {
     PRUint32 parallelPortIncCount = 0;
@@ -3726,9 +3734,15 @@ vboxDumpParallel(virDomainDefPtr def, vboxDriverPtr data, IMachine *machine, PRU
     }
 
     /* Allocate memory for the parallel ports which are enabled */
-    if ((def->nparallels > 0) && (VIR_ALLOC_N(def->parallels, def->nparallels) >= 0)) {
-        for (i = 0; i < def->nparallels; i++)
-            ignore_value(VIR_ALLOC(def->parallels[i]));
+    if (def->nparallels > 0) {
+        if (VIR_ALLOC_N(def->parallels, def->nparallels) < 0)
+            return -1;
+
+        for (i = 0; i < def->nparallels; i++) {
+            def->parallels[i] = virDomainChrDefNew(NULL);
+            if (!def->parallels[i])
+                return -1;
+        }
     }
 
     /* Now get the details about the parallel ports here */
@@ -3763,7 +3777,8 @@ vboxDumpParallel(virDomainDefPtr def, vboxDriverPtr data, IMachine *machine, PRU
                 gVBoxAPI.UIParallelPort.GetPath(parallelPort, &pathUtf16);
 
                 VBOX_UTF16_TO_UTF8(pathUtf16, &path);
-                ignore_value(VIR_STRDUP(def->parallels[parallelPortIncCount]->source->data.file.path, path));
+                if (VIR_STRDUP(def->parallels[parallelPortIncCount]->source->data.file.path, path) < 0)
+                    return -1;
 
                 parallelPortIncCount++;
 
@@ -3774,6 +3789,7 @@ vboxDumpParallel(virDomainDefPtr def, vboxDriverPtr data, IMachine *machine, PRU
             VBOX_RELEASE(parallelPort);
         }
     }
+    return 0;
 }
 
 static char *vboxDomainGetXMLDesc(virDomainPtr dom, unsigned int flags)
@@ -3912,8 +3928,11 @@ static char *vboxDomainGetXMLDesc(virDomainPtr dom, unsigned int flags)
     vboxDumpSharedFolders(def, data, machine);
     vboxDumpNetwork(def, data, machine, networkAdapterCount);
     vboxDumpAudio(def, data, machine);
-    vboxDumpSerial(def, data, machine, serialPortCount);
-    vboxDumpParallel(def, data, machine, parallelPortCount);
+
+    if (vboxDumpSerial(def, data, machine, serialPortCount) < 0)
+        goto cleanup;
+    if (vboxDumpParallel(def, data, machine, parallelPortCount) < 0)
+        goto cleanup;
 
     /* dump USB devices/filters if active */
     vboxHostDeviceGetXMLDesc(data, def, machine);