linux-kernel - Re: [PATCH] uacce: fix concurrency of fops_open and uacce

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Message-ID: <YrB4WLW/ZvKp1imo@kroah.com>
Date:   Mon, 20 Jun 2022 15:38:32 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Jean-Philippe Brucker <jean-philippe@...aro.org>
Cc:     Zhangfei Gao <zhangfei.gao@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Wangzhou <wangzhou1@...ilicon.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        linux-accelerators@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-crypto@...r.kernel.org, iommu@...ts.linux-foundation.org,
        Yang Shen <shenyang39@...wei.com>
Subject: Re: [PATCH] uacce: fix concurrency of fops_open and uacce_remove

On Mon, Jun 20, 2022 at 02:24:31PM +0100, Jean-Philippe Brucker wrote:
> >From c7c2b051ec19285bbb973f8a2a5e58bb5326e00e Mon Sep 17 00:00:00 2001
> From: Jean-Philippe Brucker <jean-philippe@...aro.org>
> Date: Mon, 20 Jun 2022 10:10:41 +0100
> Subject: [PATCH] uacce: Tidy up locking
> 
> The uacce driver must deal with a possible removal of the parent driver
> or device at any time.

No it should not, if the reference counting logic is properly set up.
The parent driver should correctly tear things down here.

> At the moment there are several issues that may
> result in use-after-free. Tidy up the locking to handle module removal.

I don't think you did that, as module removal should never happen if a
file descriptor is opened as I previously mentioned.

thanks,

greg k-h