io: fix possible double free of task error object

If a QIOTask has an error set and the calling code uses
qio_task_propagate_error() to steal the reference to
that Error object, the task would not clear its own
reference. This would lead to a double-free when
qio_task_free runs, if the caller had (correctly) freed
the Error object they now owned.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/io/task.c b/io/task.c
index 60bf1a94d5..3ce556017c 100644
--- a/io/task.c
+++ b/io/task.c
@@ -157,6 +157,7 @@ bool qio_task_propagate_error(QIOTask *task,
 {
     if (task->err) {
         error_propagate(errp, task->err);
+        task->err = NULL;
         return true;
     }