ath11k: Clear the fragment cache during key install

Currently the fragment cache setup during peer assoc is
cleared only during peer delete. In case a key reinstallation
happens with the same peer, the same fragment cache with old
fragments added before key installation could be clubbed
with fragments received after. This might be exploited
to mix fragments of different data resulting in a proper
unintended reassembled packet to be passed up the stack.

Hence flush the fragment cache on every key installation to prevent
potential attacks (CVE-2020-24587).

Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.4.0.1-01734-QCAHKSWPL_SILICONZ-1 v2

Cc: stable@vger.kernel.org
Signed-off-by: Sriram R <srirrama@codeaurora.org>
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Link: https://lore.kernel.org/r/20210511200110.218dc777836f.I9af6fc76215a35936c4152552018afb5079c5d8c@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/ath/ath11k/dp_rx.c

@@ -852,6 +852,24 @@ static void ath11k_dp_rx_frags_cleanup(struct dp_rx_tid *rx_tid, bool rel_link_d
 	__skb_queue_purge(&rx_tid->rx_frags);
 }
 
+void ath11k_peer_frags_flush(struct ath11k *ar, struct ath11k_peer *peer)
+{
+	struct dp_rx_tid *rx_tid;
+	int i;
+
+	lockdep_assert_held(&ar->ab->base_lock);
+
+	for (i = 0; i <= IEEE80211_NUM_TIDS; i++) {
+		rx_tid = &peer->rx_tid[i];
+
+		spin_unlock_bh(&ar->ab->base_lock);
+		del_timer_sync(&rx_tid->frag_timer);
+		spin_lock_bh(&ar->ab->base_lock);
+
+		ath11k_dp_rx_frags_cleanup(rx_tid, true);
+	}
+}
+
 void ath11k_peer_rx_tid_cleanup(struct ath11k *ar, struct ath11k_peer *peer)
 {
 	struct dp_rx_tid *rx_tid;

drivers/net/wireless/ath/ath11k/dp_rx.h

@@ -49,6 +49,7 @@ int ath11k_dp_peer_rx_pn_replay_config(struct ath11k_vif *arvif,
 				       const u8 *peer_addr,
 				       enum set_key_cmd key_cmd,
 				       struct ieee80211_key_conf *key);
+void ath11k_peer_frags_flush(struct ath11k *ar, struct ath11k_peer *peer);
 void ath11k_peer_rx_tid_cleanup(struct ath11k *ar, struct ath11k_peer *peer);
 void ath11k_peer_rx_tid_delete(struct ath11k *ar,
 			       struct ath11k_peer *peer, u8 tid);

drivers/net/wireless/ath/ath11k/mac.c

@@ -2779,6 +2779,12 @@ static int ath11k_mac_op_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
 	 */
 	spin_lock_bh(&ab->base_lock);
 	peer = ath11k_peer_find(ab, arvif->vdev_id, peer_addr);
+
+	/* flush the fragments cache during key (re)install to
+	 * ensure all frags in the new frag list belong to the same key.
+	 */
+	if (peer && cmd == SET_KEY)
+		ath11k_peer_frags_flush(ar, peer);
 	spin_unlock_bh(&ab->base_lock);
 
 	if (!peer) {