On Wednesday 23 June 2021 14:16:12 Johannes Berg wrote:
> On Fri, 2021-06-11 at 12:10 +0200, Pali Rohár wrote:
> >
> > @@ -341,8 +341,11 @@ static void ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
> > if (sta) {
> > if (pairwise) {
> > rcu_assign_pointer(sta->ptk[idx], new);
> > - sta->ptk_idx = idx;
> > - ieee80211_check_fast_xmit(sta);
> > + if (new) {
> > + set_sta_flag(new->sta, WLAN_STA_USES_ENCRYPTION);
> > + new->sta->ptk_idx = new->conf.keyidx;
>
> I'm not entirely sure moving that assignment under the guard is correct.
>
> > + ieee80211_check_fast_xmit(new->sta);
>
> and I'm pretty sure that moving call under the guard is incorrect,
> although in the end it probably doesn't even matter if we will drop all
> frames anyway (due to this patch).
>
> So all you need under the assignment is the flag, but also only
> theoretically, because the function cannot be called with old==NULL &&
> new==NULL, the first time around it's called we must have old==NULL (no
> key was ever installed), and so the first time it's called it must be
> old==NULL && new!=NULL, and then the flag gets set and we never want to
> clear it again, so I believe you don't need the "if (new)" condition at
> all.
>
> In the code as it was in (and before) my patch the condition is
> necessary because we use 'new' to obtain the 'sta' and 'local' pointers,
> but otherwise we don't really need it even in the current version.
>
> johannes
Now I see, thank you for explanation. So the code should be like this:
if (pairwise) {
rcu_assign_pointer(sta->ptk[idx], new);
+ set_sta_flag(sta, WLAN_STA_USES_ENCRYPTION);
sta->ptk_idx = idx;
ieee80211_check_fast_xmit(sta);
} else {
Right?
