[PULL 2/9] migration/rdma: Fix cm event use after free

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: Li Zhijian <lizhijian@cn.fujitsu.com>

Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Message-Id: <20210602023506.3821293-1-lizhijian@cn.fujitsu.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/rdma.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/migration/rdma.c b/migration/rdma.c
index 1cdb4561f3..d90b29a4b5 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -1539,16 +1539,20 @@ static int qemu_rdma_wait_comp_channel(RDMAContext *rdma)
 
                 if (pfds[1].revents) {
                     ret = rdma_get_cm_event(rdma->channel, &cm_event);
-                    if (!ret) {
-                        rdma_ack_cm_event(cm_event);
+                    if (ret) {
+                        error_report("failed to get cm event while wait "
+                                     "completion channel");
+                        return -EPIPE;
                     }
 
                     error_report("receive cm event while wait comp channel,"
                                  "cm event is %d", cm_event->event);
                     if (cm_event->event == RDMA_CM_EVENT_DISCONNECTED ||
                         cm_event->event == RDMA_CM_EVENT_DEVICE_REMOVAL) {
+                        rdma_ack_cm_event(cm_event);
                         return -EPIPE;
                     }
+                    rdma_ack_cm_event(cm_event);
                 }
                 break;
 
@@ -3285,7 +3289,6 @@ static void rdma_cm_poll_handler(void *opaque)
         error_report("get_cm_event failed %d", errno);
         return;
     }
-    rdma_ack_cm_event(cm_event);
 
     if (cm_event->event == RDMA_CM_EVENT_DISCONNECTED ||
         cm_event->event == RDMA_CM_EVENT_DEVICE_REMOVAL) {
@@ -3298,12 +3301,14 @@ static void rdma_cm_poll_handler(void *opaque)
                 rdma->return_path->error_state = -EPIPE;
             }
         }
+        rdma_ack_cm_event(cm_event);
 
         if (mis->migration_incoming_co) {
             qemu_coroutine_enter(mis->migration_incoming_co);
         }
         return;
     }
+    rdma_ack_cm_event(cm_event);
 }
 
 static int qemu_rdma_accept(RDMAContext *rdma)
-- 
2.31.1