orinoco: Avoid field-overflowing memcpy()

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally writing across neighboring array fields.

Validate the expected key size and introduce a wrapping structure
to use as the multi-field memcpy() destination so that overflows
can be correctly detected.

Signed-off-by: Kees Cook <[e-mail]>
Signed-off-by: Kalle Valo <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/net/wireless/intersil/orinoco/hw.c

···
  * tsc must be NULL or up to 8 bytes
  */
 int __orinoco_hw_set_tkip_key(struct orinoco_private *priv, int key_idx,
-			      int set_tx, const u8 *key, const u8 *rsc,
-			      size_t rsc_len, const u8 *tsc, size_t tsc_len)
+			      int set_tx, const u8 *key, size_t key_len,
+			      const u8 *rsc, size_t rsc_len,
+			      const u8 *tsc, size_t tsc_len)
 {
 	struct {
 		__le16 idx;
 		u8 rsc[ORINOCO_SEQ_LEN];
-		u8 key[TKIP_KEYLEN];
-		u8 tx_mic[MIC_KEYLEN];
-		u8 rx_mic[MIC_KEYLEN];
+		struct {
+			u8 key[TKIP_KEYLEN];
+			u8 tx_mic[MIC_KEYLEN];
+			u8 rx_mic[MIC_KEYLEN];
+		} tkip;
 		u8 tsc[ORINOCO_SEQ_LEN];
 	} __packed buf;
 	struct hermes *hw = &priv->hw;
···
 		key_idx |= 0x8000;
 
 	buf.idx = cpu_to_le16(key_idx);
-	memcpy(buf.key, key,
-	       sizeof(buf.key) + sizeof(buf.tx_mic) + sizeof(buf.rx_mic));
+	if (key_len != sizeof(buf.tkip))
+		return -EINVAL;
+	memcpy(&buf.tkip, key, sizeof(buf.tkip));
 
 	if (rsc_len > sizeof(buf.rsc))
 		rsc_len = sizeof(buf.rsc);

drivers/net/wireless/intersil/orinoco/hw.h

···
 int __orinoco_hw_setup_wepkeys(struct orinoco_private *priv);
 int __orinoco_hw_setup_enc(struct orinoco_private *priv);
 int __orinoco_hw_set_tkip_key(struct orinoco_private *priv, int key_idx,
-			      int set_tx, const u8 *key, const u8 *rsc,
-			      size_t rsc_len, const u8 *tsc, size_t tsc_len);
+			      int set_tx, const u8 *key, size_t key_len,
+			      const u8 *rsc, size_t rsc_len,
+			      const u8 *tsc, size_t tsc_len);
 int orinoco_clear_tkip_key(struct orinoco_private *priv, int key_idx);
 int __orinoco_hw_set_multicast_list(struct orinoco_private *priv,
 				    struct net_device *dev,

drivers/net/wireless/intersil/orinoco/wext.c

···
 
 			err = __orinoco_hw_set_tkip_key(priv, idx,
 				 ext->ext_flags & IW_ENCODE_EXT_SET_TX_KEY,
-				 priv->keys[idx].key,
+				 priv->keys[idx].key, priv->keys[idx].key_len,
 				 tkip_iv, ORINOCO_SEQ_LEN, NULL, 0);
 			if (err)
 				printk(KERN_ERR "%s: Error %d setting TKIP key"