netdev - Re: [PATCH] cfg80211: free the object allocated in wiphy_apply_custom

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Date:   Fri, 23 Jul 2021 17:25:29 +0800
From:   Dongliang Mu <mudongliangabcd@...il.com>
To:     xiaoqiang zhao <zhaoxiaoqiang007@...il.com>
Cc:     Johannes Berg <johannes@...solutions.net>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Luca Coelho <luciano.coelho@...el.com>,
        Ilan Peer <ilan.peer@...el.com>,
        syzbot+1638e7c770eef6b6c0d0@...kaller.appspotmail.com,
        Johannes Berg <johannes.berg@...el.com>,
        linux-wireless@...r.kernel.org,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cfg80211: free the object allocated in wiphy_apply_custom_regulatory

On Fri, Jul 23, 2021 at 5:18 PM xiaoqiang zhao
<zhaoxiaoqiang007@...il.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@...kaller.appspotmail.com
> > Fixes: beee24695157 ("cfg80211: Save the regulatory domain when setting custom regulatory")
> > Signed-off-by: Dongliang Mu <mudongliangabcd@...il.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);
> >