netdev - Re: [PATCH net 000/117] net: avoid to remove module when its debugfs is being used

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Message-ID: <62f6c2bd11ed8b25c1cd4462ebc6db870adc4229.camel@sipsolutions.net>
Date:   Thu, 08 Oct 2020 18:14:15 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     David Laight <David.Laight@...LAB.COM>,
        'Taehee Yoo' <ap420073@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Nicolai Stange <nicstange@...il.com>
Cc:     "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "wil6210@....qualcomm.com" <wil6210@....qualcomm.com>,
        "brcm80211-dev-list@...ress.com" <brcm80211-dev-list@...ress.com>,
        "b43-dev@...ts.infradead.org" <b43-dev@...ts.infradead.org>,
        "linux-bluetooth@...r.kernel.org" <linux-bluetooth@...r.kernel.org>
Subject: Re: [PATCH net 000/117] net: avoid to remove module when its
 debugfs is being used

On Thu, 2020-10-08 at 15:59 +0000, David Laight wrote:
> From: Taehee Yoo
> > Sent: 08 October 2020 16:49
> > 
> > When debugfs file is opened, its module should not be removed until
> > it's closed.
> > Because debugfs internally uses the module's data.
> > So, it could access freed memory.
> > 
> > In order to avoid panic, it just sets .owner to THIS_MODULE.
> > So that all modules will be held when its debugfs file is opened.
> 
> Can't you fix it in common code?

Yeah I was just wondering that too - weren't the proxy_fops even already
intended to fix this?

The modules _should_ be removing the debugfs files, and then the
proxy_fops should kick in, no?

So where's the issue?

johannes