sched: Fix fork() error path to not crash

In dup_task_struct(), if arch_dup_task_struct() fails, the clean up code fails to clean up correctly. That's because the clean up code depends on unininitalized ti->task pointer. We fix this by making sure that the task and thread_info know about each other before we attempt to take the error path. Signed-off-by: Salman Qazi <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
kyagi · Jul 5, 2012 · 164c33c · 164c33c
1 parent 9e85a6f
commit 164c33c
Showing 1 changed file with 8 additions and 3 deletions.
diff --git a/kernel/fork.c b/kernel/fork.c
@@ -304,12 +304,17 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 	}
 
 	err = arch_dup_task_struct(tsk, orig);
-	if (err)
-		goto out;
 
+	/*
+	 * We defer looking at err, because we will need this setup
+	 * for the clean up path to work correctly.
+	 */
 	tsk->stack = ti;
-
 	setup_thread_stack(tsk, orig);
+
+	if (err)
+		goto out;
+
 	clear_user_return_notifier(tsk);
 	clear_tsk_need_resched(tsk);
 	stackend = end_of_stack(tsk);