cfg80211: protect fools returning NULL in add_virtual_intf

Callback add_virtual_intf is supposed to return ERR_PTR and trying to
return NULL results in some "Unable to handle kernel paging request",
etc. As it may be complicated to debug & trace, let's catch it (WARN).

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index dd5a827f9cb0..5cfd75dfff67 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2645,7 +2645,10 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
         wdev = rdev_add_virtual_intf(rdev,
                                 nla_data(info->attrs[NL80211_ATTR_IFNAME]),
                                 type, err ? NULL : &flags, &params);
-        if (IS_ERR(wdev)) {
+        if (WARN_ON(!wdev)) {
+                nlmsg_free(msg);
+                return -EPROTO;
+        } else if (IS_ERR(wdev)) {
                 nlmsg_free(msg);
                 return PTR_ERR(wdev);
         }