mac80211: fix debugfs default key oops

Under certain circumstances (in AP mode) the debugfs function
that is supposed to add the default key symlink can encounter
a NULL default_key pointer. This patch makes it handle that
situtation gracefully.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 12 insertions, 3 deletions

diff --git a/net/mac80211/debugfs_key.c b/net/mac80211/debugfs_key.c
index 879e7210458a..19efc3a6a932 100644
--- a/net/mac80211/debugfs_key.c
+++ b/net/mac80211/debugfs_key.c
@@ -255,14 +255,23 @@ void ieee80211_debugfs_key_remove(struct ieee80211_key *key)
 void ieee80211_debugfs_key_add_default(struct ieee80211_sub_if_data *sdata)
 {
         char buf[50];
+        struct ieee80211_key *key;
 
         if (!sdata->debugfsdir)
                 return;
 
-        sprintf(buf, "../keys/%d", sdata->default_key->debugfs.cnt);
-        sdata->debugfs.default_key =
-                debugfs_create_symlink("default_key", sdata->debugfsdir, buf);
+        /* this is running under the key lock */
+
+        key = sdata->default_key;
+        if (key) {
+                sprintf(buf, "../keys/%d", key->debugfs.cnt);
+                sdata->debugfs.default_key =
+                        debugfs_create_symlink("default_key",
+                                               sdata->debugfsdir, buf);
+        } else
+                ieee80211_debugfs_key_remove_default(sdata);
 }
+
 void ieee80211_debugfs_key_remove_default(struct ieee80211_sub_if_data *sdata)
 {
         if (!sdata)