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>

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 0589f55..396e8fc 100644 (file)
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -2688,7 +2688,7 @@ void cfg80211_send_unprot_disassoc(struct net_device *dev, const u8 *buf,
  * @dev: network device
  * @addr: The source MAC address of the frame
  * @key_type: The key type that the received frame used
- * @key_id: Key identifier (0..3)
+ * @key_id: Key identifier (0..3). Can be -1 if missing.
  * @tsc: The TSC value of the frame that generated the MIC failure (6 octets)
  * @gfp: allocation flags
  *

diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index 9dc3b5f..d91c1a2 100644 (file)
--- 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 98fa8eb..f07602d 100644 (file)
--- 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);