workqueue: Fix an use after free in init_rescuer()

We need to preserve error code before freeing "rescuer".

Fixes: f187b6974f6df ("workqueue: Use IS_ERR and PTR_ERR instead of PTR_ERR_OR_ZERO.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index ddf0537dce140dd88e042a1395d5ca90657d9c06..10ed8d761e0b7b0681d73313023326b08a23d32d 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4197,6 +4197,7 @@ static int wq_clamp_max_active(int max_active, unsigned int flags,
 static int init_rescuer(struct workqueue_struct *wq)
 {
        struct worker *rescuer;
 static int init_rescuer(struct workqueue_struct *wq)
 {
        struct worker *rescuer;

+       int ret;

 
        if (!(wq->flags & WQ_MEM_RECLAIM))
                return 0;
 
        if (!(wq->flags & WQ_MEM_RECLAIM))
                return 0;


@@ -4208,8 +4209,9 @@ static int init_rescuer(struct workqueue_struct *wq)
        rescuer->rescue_wq = wq;
        rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", wq->name);
        if (IS_ERR(rescuer->task)) {
        rescuer->rescue_wq = wq;
        rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", wq->name);
        if (IS_ERR(rescuer->task)) {

+               ret = PTR_ERR(rescuer->task);

                kfree(rescuer);
                kfree(rescuer);

-               return PTR_ERR(rescuer->task);
+               return ret;

        }
 
        wq->rescuer = rescuer;
        }
 
        wq->rescuer = rescuer;