mac80211: fix CMAC races

Just like TKIP and CCMP, CMAC has the PN race.
It might not actually be possible to hit it now
since there aren't multiple ACs for management
frames, but fix it anyway.

Also move scratch buffers onto the stack.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/key.h b/net/mac80211/key.h
index 05ce4c0..fcb52eb 100644
--- a/net/mac80211/key.h
+++ b/net/mac80211/key.h
@@ -97,14 +97,11 @@
 #endif
 		} ccmp;
 		struct {
-			u8 tx_pn[6];
+			atomic64_t tx_pn;
 			u8 rx_pn[6];
 			struct crypto_cipher *tfm;
 			u32 replays; /* dot11RSNAStatsCMACReplays */
 			u32 icverrors; /* dot11RSNAStatsCMACICVErrors */
-			/* scratch buffers for virt_to_page() (crypto API) */
-			u8 tx_crypto_buf[2 * AES_BLOCK_LEN];
-			u8 rx_crypto_buf[2 * AES_BLOCK_LEN];
 		} aes_cmac;
 	} u;