Re: [PATCH] cfg80211: free the object allocated in wiphy_apply_custom_regulatory
From: Dongliang Mu
Date: Fri Jul 23 2021 - 05:14:32 EST
On Fri, Jul 23, 2021 at 4:37 PM Johannes Berg <johannes@xxxxxxxxxxxxxxxx> 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 .
> Perhaps somewhere we have a case where wiphy->regd is leaked, but than
> that should be fixed more generally in cfg80211?