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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 17:13:59 +0800	[thread overview]
Message-ID: <CAD-N9QWDNvo_3bdB=8edyYWvEV=b-66Tx-P6_7JGgrSYshDh0A@mail.gmail.com> (raw)
In-Reply-To: <d2b0f847dbf6b6d1e585ef8de1d9d367f8d9fd3b.camel@sipsolutions.net>

On Fri, Jul 23, 2021 at 4:37 PM Johannes Berg <johannes@sipsolutions.net> wrote:
>
> On Fri, 2021-07-23 at 13:09 +0800, Dongliang Mu wrote:
> > The commit beee24695157 ("cfg80211: Save the regulatory domain when
> > setting custom regulatory") forgets to free the newly allocated regd
> > object.
>
> Not really? It's not forgetting it, it just saves it?

Yes, it saves the regd object in the function wiphy_apply_custom_regulatory.

But its parent function - mac80211_hwsim_new_radio forgets to free
this object when the ieee80211_register_hw fails.

>
> +       new_regd = reg_copy_regd(regd);
> +       if (IS_ERR(new_regd))
> +               return;
> +
> +       tmp = get_wiphy_regdom(wiphy);
> +       rcu_assign_pointer(wiphy->regd, new_regd);
> +       rcu_free_regdom(tmp);
>
> > Fix this by freeing the regd object in the error handling code and
> > deletion function - mac80211_hwsim_del_radio.
>
> This can't be right - the same would affect all other users of that
> function, no?

The problem occurs in the error handling code of
mac80211_hwsim_new_radio, not wiphy_apply_custom_regulatory. My commit
message may be not very clear.

So I think the code in the mac80211_hwsim_del_radio paired with
mac80211_hwsim_new_radio should be changed correspondingly. If I miss
any problems, please let me know.

I have successfully tested my patch in the syzbot dashboard [1].

[1] https://syzkaller.appspot.com/bug?extid=1638e7c770eef6b6c0d0

>
> Perhaps somewhere we have a case where wiphy->regd is leaked, but than
> that should be fixed more generally in cfg80211?
>
> johannes
>

  reply	other threads:[~2021-07-23  9:14 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 [this message]
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
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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