cfg80211: fix interface combinations check

If a given interface combination doesn't contain
a required interface type then we missed checking
that and erroneously allowed it even though iface
type wasn't there at all. Add a check that makes
sure that all interface types are accounted for.

Cc: stable@kernel.org
Reported-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 18 insertions, 1 deletions

diff --git a/net/wireless/util.c b/net/wireless/util.c
index 55d99466babb..8f2d68fc3a44 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -935,6 +935,7 @@ int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
                                   enum nl80211_iftype iftype)
 {
         struct wireless_dev *wdev_iter;
+        u32 used_iftypes = BIT(iftype);
         int num[NUM_NL80211_IFTYPES];
         int total = 1;
         int i, j;
@@ -961,6 +962,7 @@ int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
 
                 num[wdev_iter->iftype]++;
                 total++;
+                used_iftypes |= BIT(wdev_iter->iftype);
         }
         mutex_unlock(&rdev->devlist_mtx);
 
@@ -970,6 +972,7 @@ int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
         for (i = 0; i < rdev->wiphy.n_iface_combinations; i++) {
                 const struct ieee80211_iface_combination *c;
                 struct ieee80211_iface_limit *limits;
+                u32 all_iftypes = 0;
 
                 c = &rdev->wiphy.iface_combinations[i];
 
@@ -984,6 +987,7 @@ int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
                         if (rdev->wiphy.software_iftypes & BIT(iftype))
                                 continue;
                         for (j = 0; j < c->n_limits; j++) {
+                                all_iftypes |= limits[j].types;
                                 if (!(limits[j].types & BIT(iftype)))
                                         continue;
                                 if (limits[j].max < num[iftype])
@@ -991,7 +995,20 @@ int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev,
                                 limits[j].max -= num[iftype];
                         }
                 }
-                /* yay, it fits */
+
+                /*
+                 * Finally check that all iftypes that we're currently
+                 * using are actually part of this combination. If they
+                 * aren't then we can't use this combination and have
+                 * to continue to the next.
+                 */
+                if ((all_iftypes & used_iftypes) != used_iftypes)
+                        goto cont;
+
+                /*
+                 * This combination covered all interface types and
+                 * supported the requested numbers, so we're good.
+                 */
                 kfree(limits);
                 return 0;
  cont: