1 files changed, 20 insertions, 24 deletions

diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index c9edfcb7a13b..d65728220763 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -301,22 +301,16 @@ ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
 }
 
 
-static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
+static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *b_0, u8 *aad,
                                 int encrypted)
 {
         __le16 mask_fc;
         int a4_included, mgmt;
         u8 qos_tid;
-        u8 *b_0, *aad;
-        u16 data_len, len_a;
+        u16 len_a;
         unsigned int hdrlen;
         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 
-        memset(scratch, 0, 6 * AES_BLOCK_SIZE);
-
-        b_0 = scratch + 3 * AES_BLOCK_SIZE;
-        aad = scratch + 4 * AES_BLOCK_SIZE;
-
         /*
          * Mask FC: zero subtype b4 b5 b6 (if not mgmt)
          * Retry, PwrMgt, MoreData; set Protected
@@ -338,20 +332,21 @@ static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
         else
                 qos_tid = 0;
 
-        data_len = skb->len - hdrlen - IEEE80211_CCMP_HDR_LEN;
-        if (encrypted)
-                data_len -= IEEE80211_CCMP_MIC_LEN;
+        /* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC
+         * mode authentication are not allowed to collide, yet both are derived
+         * from this vector b_0. We only set L := 1 here to indicate that the
+         * data size can be represented in (L+1) bytes. The CCM layer will take
+         * care of storing the data length in the top (L+1) bytes and setting
+         * and clearing the other bits as is required to derive the two IVs.
+         */
+        b_0[0] = 0x1;
 
-        /* First block, b_0 */
-        b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
         /* Nonce: Nonce Flags | A2 | PN
          * Nonce Flags: Priority (b0..b3) | Management (b4) | Reserved (b5..b7)
          */
         b_0[1] = qos_tid | (mgmt << 4);
         memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
         memcpy(&b_0[8], pn, IEEE80211_CCMP_PN_LEN);
-        /* l(m) */
-        put_unaligned_be16(data_len, &b_0[14]);
 
         /* AAD (extra authenticate-only data) / masked 802.11 header
          * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
@@ -407,7 +402,8 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
         u8 *pos;
         u8 pn[6];
         u64 pn64;
-        u8 scratch[6 * AES_BLOCK_SIZE];
+        u8 aad[2 * AES_BLOCK_SIZE];
+        u8 b_0[AES_BLOCK_SIZE];
 
         if (info->control.hw_key &&
             !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
@@ -460,9 +456,9 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
                 return 0;
 
         pos += IEEE80211_CCMP_HDR_LEN;
-        ccmp_special_blocks(skb, pn, scratch, 0);
-        ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, scratch, pos, len,
-                                  pos, skb_put(skb, IEEE80211_CCMP_MIC_LEN));
+        ccmp_special_blocks(skb, pn, b_0, aad, 0);
+        ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, b_0, aad, pos, len,
+                                  skb_put(skb, IEEE80211_CCMP_MIC_LEN));
 
         return 0;
 }
@@ -525,16 +521,16 @@ ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
         }
 
         if (!(status->flag & RX_FLAG_DECRYPTED)) {
-                u8 scratch[6 * AES_BLOCK_SIZE];
+                u8 aad[2 * AES_BLOCK_SIZE];
+                u8 b_0[AES_BLOCK_SIZE];
                 /* hardware didn't decrypt/verify MIC */
-                ccmp_special_blocks(skb, pn, scratch, 1);
+                ccmp_special_blocks(skb, pn, b_0, aad, 1);
 
                 if (ieee80211_aes_ccm_decrypt(
-                            key->u.ccmp.tfm, scratch,
+                            key->u.ccmp.tfm, b_0, aad,
                             skb->data + hdrlen + IEEE80211_CCMP_HDR_LEN,
                             data_len,
-                            skb->data + skb->len - IEEE80211_CCMP_MIC_LEN,
-                            skb->data + hdrlen + IEEE80211_CCMP_HDR_LEN))
+                            skb->data + skb->len - IEEE80211_CCMP_MIC_LEN))
                         return RX_DROP_UNUSABLE;
         }