mac80211: fix rx->key NULL dereference during mic failure

Sometimes when reporting a MIC failure rx->key may be unset. This
code path is hit when receiving a packet meant for a multicast
address, and decryption is performed in HW.

Fortunately, the failing key_idx is not used for anything up to
(and including) usermode, so we allow ourselves to drop it on the
way up when a key cannot be retrieved.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
Cc: stable@kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 9 insertions, 2 deletions

diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index 9dc3b5f26e80..d91c1a26630d 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -154,7 +154,13 @@ update_iv:
         return RX_CONTINUE;
 
 mic_fail:
-        mac80211_ev_michael_mic_failure(rx->sdata, rx->key->conf.keyidx,
+        /*
+         * In some cases the key can be unset - e.g. a multicast packet, in
+         * a driver that supports HW encryption. Send up the key idx only if
+         * the key is set.
+         */
+        mac80211_ev_michael_mic_failure(rx->sdata,
+                                        rx->key ? rx->key->conf.keyidx : -1,
                                         (void *) skb->data, NULL, GFP_ATOMIC);
         return RX_DROP_UNUSABLE;
 }
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 98fa8eb6cc4b..f07602d7bf68 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -6463,7 +6463,8 @@ void nl80211_michael_mic_failure(struct cfg80211_registered_device *rdev,
         if (addr)
                 NLA_PUT(msg, NL80211_ATTR_MAC, ETH_ALEN, addr);
         NLA_PUT_U32(msg, NL80211_ATTR_KEY_TYPE, key_type);
-        NLA_PUT_U8(msg, NL80211_ATTR_KEY_IDX, key_id);
+        if (key_id != -1)
+                NLA_PUT_U8(msg, NL80211_ATTR_KEY_IDX, key_id);
         if (tsc)
                 NLA_PUT(msg, NL80211_ATTR_KEY_SEQ, 6, tsc);