[PATCH 3/8] spapr: Fix memory leak of vmstate_spapr_event_entry

[g00517791]

From: Jinhao Gao <gaojinhao@huawei.com>

When VM migrate VMState of spapr_event_log_entry, the field(extended_log)
of spapr_event_log_entry having a flag of VMS_ALLOC needs to allocate
memory. If the dst doesn't free memory which has been allocated for
SaveStateEntry of spapr_event_log_entry before dst loads device state,
it may result that the pointer of extended_log is overlaid when vm loads.
We add the pre_load func to free memory, which prevents memory leak.

Signed-off-by: Jinhao Gao <gaojinhao@huawei.com>
---
 hw/ppc/spapr.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 489cefcb81..ddfed1e7ca 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1799,10 +1799,22 @@ static bool spapr_pending_events_needed(void *opaque)
     return !QTAILQ_EMPTY(&spapr->pending_events);
 }
 
+static int spapr_event_log_entry_pre_load(void *opaque)
+{
+    SpaprEventLogEntry *entry = opaque;
+
+    g_free(entry->extended_log);
+    entry->extended_log = NULL;
+    entry->extended_length = 0;
+
+    return 0;
+}
+
 static const VMStateDescription vmstate_spapr_event_entry = {
     .name = "spapr_event_log_entry",
     .version_id = 1,
     .minimum_version_id = 1,
+    .pre_load = spapr_event_log_entry_pre_load,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32(summary, SpaprEventLogEntry),
         VMSTATE_UINT32(extended_length, SpaprEventLogEntry),
-- 
2.23.0