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From: Dongliang Mu <mudongliangabcd@gmail.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Kalle Valo <kvalo@codeaurora.org>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Luca Coelho <luciano.coelho@intel.com>,
	Ilan Peer <ilan.peer@intel.com>,
	syzbot+1638e7c770eef6b6c0d0@syzkaller.appspotmail.com,
	linux-wireless@vger.kernel.org,
	"open list:NETWORKING [GENERAL]" <netdev@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Dan Carpenter <dan.carpenter@oracle.com>
Subject: Re: [PATCH] cfg80211: free the object allocated in wiphy_apply_custom_regulatory
Date: Fri, 23 Jul 2021 17:59:39 +0800	[thread overview]
Message-ID: <CAD-N9QV02fnr8LLSwxTuyevYgkL_2aicO2b_7uZ46s6BGKaTmw@mail.gmail.com> (raw)
In-Reply-To: <e549fbb09d7c618762996aca4242c2ae50f85a5c.camel@sipsolutions.net>

On Fri, Jul 23, 2021 at 5:42 PM Johannes Berg <johannes@sipsolutions.net> wrote:
>
> Hi,
>
> On Fri, 2021-07-23 at 17:30 +0800, Dongliang Mu wrote:
> > if zhao in the thread is right, we don't need to add this free
> > operation to wiphy_free().
>
> Actually, no, that statement is not true.
>
> All that zhao claimed was that the free happens correctly during
> unregister (or later), and that is indeed true, since it happens from
>
> ieee80211_unregister_hw()
>  -> wiphy_unregister()
>  -> wiphy_regulatory_deregister()
>

Thanks for your explanation. Now the situation is more clear.

>
> However, syzbot of course is also correct. Abstracting a bit and
> ignoring mac80211, the problem is that here we assign it before
> wiphy_register(), then wiphy_register() doesn't get called or fails, and
> therefore we don't call wiphy_unregister(), only wiphy_free().

Yes, you're right. In this case, wiphy_register is not called. We
should not call wiphy_unregister() to clean up anything.

>
> Hence the leak.
>
> But you can also easily see from that description that it's not related
> to hwsim - we should add a secondary round of cleanups in wiphy_free()
> or even move the call to wiphy_regulatory_deregister() into
> wiphy_free(), we need to look what else this does to see if we can move
> it or not.

I agree to move the cleanup operation of regd to wiphy_free API.
That's the partial functionability of this function.

>
> johannes
>

  reply	other threads:[~2021-07-23 10:00 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23  5:09 Dongliang Mu
2021-07-23  5:16 ` Dongliang Mu
2021-07-23  8:37 ` Johannes Berg
2021-07-23  9:13   ` Dongliang Mu
2021-07-23  9:18     ` Johannes Berg
2021-07-23  9:30       ` Dongliang Mu
2021-07-23  9:42         ` Johannes Berg
2021-07-23  9:59           ` Dongliang Mu [this message]
2021-07-23  9:18 ` xiaoqiang zhao
2021-07-23  9:25   ` Dongliang Mu
2021-07-23  9:36     ` xiaoqiang zhao
2021-07-23  9:44       ` Dongliang Mu

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