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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: 1f8675da4382f6e("nonblocking concurrent task execution via background workers")

Signed-off-by: Maksim Korotkov <m.korotkov@postgrespro.ru>
pull/7694/head
Maksim Korotkov 2024-09-30 11:00:49 +03:00
parent f6959715dc
commit 73205b1521
1 changed files with 5 additions and 1 deletions
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6
src/backend/distributed/utils/background_jobs.c
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@ -706,8 +706,12 @@ TaskConcurrentCancelCheck(TaskExecutionContext *taskExecutionContext)
BackgroundExecutorHashEntry *handleEntry = taskExecutionContext->handleEntry; BackgroundExecutorHashEntry *handleEntry = taskExecutionContext->handleEntry;
BackgroundTask *task = GetBackgroundTaskByTaskId(handleEntry->taskid); BackgroundTask *task = GetBackgroundTaskByTaskId(handleEntry->taskid);
taskExecutionContext->task = task; 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 * being in that step means that a concurrent cancel or removal happened. we should