rpc: securely erase the message buffers

While only a couple of the message types include sensitive data,
the overhead of calling secure erase is not noticable enough
to worry about making the erasure selective per type. Thus it is
simplest to unconditionally securely erase the buffer.

Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

src/rpc/virnetmessage.c

@@ -28,6 +28,7 @@
 #include "virlog.h"
 #include "virfile.h"
 #include "virutil.h"
+#include "virsecureerase.h"
 
 #define VIR_FROM_THIS VIR_FROM_RPC
 
@@ -65,6 +66,7 @@ virNetMessageClearPayload(virNetMessage *msg)
 {
     virNetMessageClearFDs(msg);
 
+    virSecureErase(msg->buffer, msg->bufferLength);
     msg->bufferOffset = 0;
     msg->bufferLength = 0;
     VIR_FREE(msg->buffer);