Re: [PATCH] cfg80211: free the object allocated in wiphy_apply_custom_regulatory

From: Dongliang Mu <mudongliangabcd@gmail.com>
To: xiaoqiang zhao <zhaoxiaoqiang007@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
	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,
	Johannes Berg <johannes.berg@intel.com>,
	linux-wireless@vger.kernel.org,
	"open list:NETWORKING [GENERAL]" <netdev@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] cfg80211: free the object allocated in wiphy_apply_custom_regulatory
Date: Fri, 23 Jul 2021 17:25:29 +0800	[thread overview]
Message-ID: <CAD-N9QXO4bX6SzMNir0fin0wVAZYhsS8-triiWPjY+Rz2WCy1w@mail.gmail.com> (raw)
In-Reply-To: <6fa2aecc-ab64-894d-77c2-0a19b524cc03@gmail.com>

On Fri, Jul 23, 2021 at 5:18 PM xiaoqiang zhao
<zhaoxiaoqiang007@gmail.com> wrote:
>
>
>
> 在 2021/7/23 13:09, Dongliang Mu 写道:
> > The commit beee24695157 ("cfg80211: Save the regulatory domain when
> > setting custom regulatory") forgets to free the newly allocated regd
> > object.
> >
> > Fix this by freeing the regd object in the error handling code and
> > deletion function - mac80211_hwsim_del_radio.
> >
> > Reported-by: syzbot+1638e7c770eef6b6c0d0@syzkaller.appspotmail.com
> > Fixes: beee24695157 ("cfg80211: Save the regulatory domain when setting custom regulatory")
> > Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
> > ---
> >  drivers/net/wireless/mac80211_hwsim.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
> > index ffa894f7312a..20b870af6356 100644
> > --- a/drivers/net/wireless/mac80211_hwsim.c
> > +++ b/drivers/net/wireless/mac80211_hwsim.c
> > @@ -3404,6 +3404,8 @@ static int mac80211_hwsim_new_radio(struct genl_info *info,
> >       debugfs_remove_recursive(data->debugfs);
> >       ieee80211_unregister_hw(data->hw);
> >  failed_hw:
> > +     if (param->regd)
> > +             kfree_rcu(get_wiphy_regdom(data->hw->wiphy));
> >       device_release_driver(data->dev);
>
> hw->wiphy->regd may be NULL if previous reg_copy_regd failed, so how about:
> if (hw->wiphy->regd)
>         rcu_free_regdom(get_wiphy_regdom(hw->wiphy))

Previously I would like to use this API(rcu_free_regdom), but it is
static and located in non-global header file - reg.h.

>
> >  failed_bind:
> >       device_unregister(data->dev);
> > @@ -3454,6 +3456,8 @@ static void mac80211_hwsim_del_radio(struct mac80211_hwsim_data *data,
> >  {
> >       hwsim_mcast_del_radio(data->idx, hwname, info);
> >       debugfs_remove_recursive(data->debugfs);
> > +     if (data->regd)
> > +             kfree_rcu(get_wiphy_regdom(data->hw->wiphy));
> this is not correct, because ieee80211_unregister_hw below will free
> data->hw_wiphy->regd

Can you point out the concrete code releasing regd? Maybe the link to elixir.

> >       ieee80211_unregister_hw(data->hw);
> >       device_release_driver(data->dev);
> >       device_unregister(data->dev);
> >