wifi: mac80211: fix potential key use-after-free

When ieee80211_key_link() is called by ieee80211_gtk_rekey_add()
but returns 0 due to KRACK protection (identical key reinstall),
ieee80211_gtk_rekey_add() will still return a pointer into the
key, in a potential use-after-free. This normally doesn't happen
since it's only called by iwlwifi in case of WoWLAN rekey offload
which has its own KRACK protection, but still better to fix, do
that by returning an error code and converting that to success on
the cfg80211 boundary only, leaving the error for bad callers of
ieee80211_gtk_rekey_add().

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: fdf7cb4185b6 ("mac80211: accept key reinstall without changing anything")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 45e7a5d9c7d94206f1af8f5ecf142d156deb6797..e883c41a2163bac70f6416ecff747cffe30eb8b8 100644 (file)
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -566,6 +566,9 @@ static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
        }
 
        err = ieee80211_key_link(key, link, sta);
+       /* KRACK protection, shouldn't happen but just silently accept key */
+       if (err == -EALREADY)
+               err = 0;
 
  out_unlock:
        mutex_unlock(&local->sta_mtx);

diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 13050dc9321f197d6aaa1c55235302bfa2ecf6f1..84ba20c3e3dcd66c39071125c63729fd7dfcb163 100644 (file)
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -905,7 +905,7 @@ int ieee80211_key_link(struct ieee80211_key *key,
         */
        if (ieee80211_key_identical(sdata, old_key, key)) {
                ieee80211_key_free_unused(key);
-               ret = 0;
+               ret = -EALREADY;
                goto out;
        }