concurrent task execution: fixed dereference of NULL pointer

In the function TaskConcurrentCancelCheck() the pointer "task" was utilized after checking against NULL, which can lead to dereference of the null pointer. To avoid the problem, added a separate handling of the case when the pointer is null with an interruption of execution. Fixes: 1f8675d("nonblocking concurrent task execution via background workers") Signed-off-by: Maksim Korotkov <[email protected]>
citusdata · Oct 4, 2024 · 73205b1 · 73205b1
1 parent f695971
commit 73205b1
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/src/backend/distributed/utils/background_jobs.c b/src/backend/distributed/utils/background_jobs.c
@@ -706,8 +706,12 @@ TaskConcurrentCancelCheck(TaskExecutionContext *taskExecutionContext)
 	BackgroundExecutorHashEntry *handleEntry = taskExecutionContext->handleEntry;
 	BackgroundTask *task = GetBackgroundTaskByTaskId(handleEntry->taskid);
 	taskExecutionContext->task = task;
+	if (!task)
+	{
+		ereport(ERROR, (errmsg("unexpected missing task id: %ld", handleEntry->taskid)));
+	}
 
-	if (!task || task->status == BACKGROUND_TASK_STATUS_CANCELLING)
+	if (task->status == BACKGROUND_TASK_STATUS_CANCELLING)
 	{
 		/*
 		 * being in that step means that a concurrent cancel or removal happened. we should