qmp: forbid qmp_cont in RUN_STATE_FINISH_MIGRATE

qmp_cont in RUN_STATE_FINISH_MIGRATE may lead to moving vm to
RUN_STATE_RUNNING, before actual migration finish. So, when migration
thread will try to go to RUN_STATE_POSTMIGRATE, assuming transition
RUN_STATE_FINISH_MIGRATE->RUN_STATE_POSTMIGRATE, it will crash, as
current state is RUN_STATE_RUNNING, and transition
RUN_STATE_RUNNING->RUN_STATE_POSTMIGRATE is forbidden.

Reported-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/qmp.c b/qmp.c
index b92d62cd5f..fa1b3c1577 100644
--- a/qmp.c
+++ b/qmp.c
@@ -156,6 +156,9 @@ void qmp_cont(Error **errp)
         return;
     } else if (runstate_check(RUN_STATE_SUSPENDED)) {
         return;
+    } else if (runstate_check(RUN_STATE_FINISH_MIGRATE)) {
+        error_setg(errp, "Migration is not finalized yet");
+        return;
     }
 
     for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {