From: Greg KH <gregkh@linuxfoundation.org>
To: sicong <congei42@163.com>
Cc: peter.chen@kernel.org, pawell@cadence.com, rogerq@kernel.org,
linux-usb@vger.kernel.org
Subject: Re: Bug report: usb: cdns3: cdns3-gadget.c: use-after-free bug in cdns3_gadget_exit due to race condition
Date: Sun, 12 May 2024 13:29:31 +0100 [thread overview]
Message-ID: <2024051207-grandson-desktop-85ea@gregkh> (raw)
In-Reply-To: <7f5719b.8700.18f67b324d3.Coremail.congei42@163.com>
On Sat, May 11, 2024 at 08:49:04PM +0800, sicong wrote:
>
>
> usb: cdns3: cdns3-gadget.c: use-after-free bug in cdns3_gadget_exit due to
> race condition
>
> This bug exists in drivers/usb/cdns3/cdns3-gadget.c. Function
> __cdns3_gadget_init will call cdns3_gadget_start to do the futher jobs
> during the initialization proccess of cdns3 gadget. In cdns3_gadget_start,
> &priv_dev->pending_status_wq is bound with cdns3_pending_setup_status_handler.
> Then this work will be added to system_freezable_wq in cdns3_gadget_ep0_queue.
> Here is the code.
> queue_work(system_freezable_wq, &priv_dev->pending_status_wq);
>
> If we call cdns3_gadget_exit to remove the device and make cleanup,
> there are some unfinished works. This function will call cdns3_free_all_eps to
> free all the endpoints. However, if cdns3_pending_setup_status_handler is
> scheduled to run after the free job, it will cause use-after-free error as
> cdns3_pending_setup_status_handler will use the endpoint in the following code.
> request->complete(&priv_dev->eps[0]->endpoint, request);
>
> The possible execution flow that may lead to this issue is as follows:
> CPU0 CPU1
> | __cdns3_gadget_init
> | cdns3_gadget_start
> cdns3_gadget_exit |
> cdns3_free_all_eps |
> devm_kfree (free) |
> | cdns3_pending_setup_status_handler
> | &priv_dev->eps[0]->endpoint (use)
>
>
> This bug may be fixed by adding the following code in cdns3_gadget_exit.
> cancel_work_sync(&priv_dev->pending_status_wq);
> cancel_work_sync(&priv_dev->aligned_buf_wq);
Can you please provide a patch for this so we can apply it and give you
the credit for fixing the issue?
thanks,
greg k-h
prev parent reply other threads:[~2024-05-12 12:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-11 12:49 Bug report: usb: cdns3: cdns3-gadget.c: use-after-free bug in cdns3_gadget_exit due to race condition sicong
2024-05-12 12:29 ` Greg KH [this message]
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