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

From: Johannes Berg
Date: Fri Jul 23 2021 - 05:42:53 EST


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

-> wiphy_unregister()
-> wiphy_regulatory_deregister()

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().

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.