mac80211_hwsim: calculate if_combination.max_interfaces

If we just set this to 2048, and have multiple limits you
can select from, the total number might run over and cause
a warning in cfg80211. This doesn't make sense, so we just
calculate the total max_interfaces now.

Reported-by: syzbot+8f91bd563bbff230d0ee@syzkaller.appspotmail.com
Fixes: e78bec0d2ba0 ("mac80211_hwsim: allow setting iftype support")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 0838af04d681a3e37f71b8d47cb58435ffbac5fb..524eb580599571c9c4e4ee782d760e0287389ddd 100644 (file)
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -2644,7 +2644,7 @@ static int mac80211_hwsim_new_radio(struct genl_info *info,
        enum nl80211_band band;
        const struct ieee80211_ops *ops = &mac80211_hwsim_ops;
        struct net *net;
-       int idx;
+       int idx, i;
        int n_limits = 0;
 
        if (WARN_ON(param->channels > 1 && !param->use_chanctx))
@@ -2768,12 +2768,23 @@ static int mac80211_hwsim_new_radio(struct genl_info *info,
                goto failed_hw;
        }
 
+       data->if_combination.max_interfaces = 0;
+       for (i = 0; i < n_limits; i++)
+               data->if_combination.max_interfaces +=
+                       data->if_limits[i].max;
+
        data->if_combination.n_limits = n_limits;
-       data->if_combination.max_interfaces = 2048;
        data->if_combination.limits = data->if_limits;
 
-       hw->wiphy->iface_combinations = &data->if_combination;
-       hw->wiphy->n_iface_combinations = 1;
+       /*
+        * If we actually were asked to support combinations,
+        * advertise them - if there's only a single thing like
+        * only IBSS then don't advertise it as combinations.
+        */
+       if (data->if_combination.max_interfaces > 1) {
+               hw->wiphy->iface_combinations = &data->if_combination;
+               hw->wiphy->n_iface_combinations = 1;
+       }
 
        if (param->ciphers) {
                memcpy(data->ciphers, param->ciphers,