Messages in this thread | | | Subject | Re: [PATCH] workqueue: Fix double kfree(rescuer) in destroy_workqueue() | From | qzhang2 <> | Date | Mon, 25 May 2020 14:43:31 +0800 |
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Sorry I didn't describe clearly
I describe the meaning as follows:
destroy_workqueue: if(wq->rescuer) struct worker *rescuer = wq->rescuer kfree(rescuer) //first kfree
if (!(wq->flags & WQ_UNBOUND)) call_rcu(&wq->rcu, rcu_free_wq) rcu_free_wq kfree(wq->rescuer) //second kfree
there are double free.
On 5/24/20 11:33 PM, Markus Elfring wrote: >> When destroy_workqueue if rescuer worker exist,wq->rescuer pointer be >> kfree. if sanity checks passed. the func call_rcu(&wq->rcu, rcu_free_wq) >> will be called if the wq->flags & WQ_UNBOUND is false,in rcu_free_wq >> func wq->rescuer pointer was kfree again. > > 1. I suggest to improve also this change description. > Do you try to explain here that a call of the function “free_workqueue_attrs” > (or “free_percpu”) would perform sufficient clean-up of system resources > in this use case? > > 2. You proposed to delete the function call “kfree(wq->rescuer)” from > the implementation of the function “rcu_free_wq”. > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/kernel/workqueue.c?id=c11d28ab4a691736e30b49813fb801847bd44e83#n3482 > https://elixir.bootlin.com/linux/v5.7-rc6/source/kernel/workqueue.c#L3482 > > This function name should be specified also in the patch subject, > shouldn't it? > > 3. Would you like to add the tag “Fixes” to the commit message? > > Regards, > Markus >
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