diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 651705565dfb..74186c2d9e6e 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -99,6 +99,7 @@ struct ieee80211_fragment_entry {
 	u8 rx_queue;
 	bool check_sequential_pn; /* needed for CCMP/GCMP */
 	u8 last_pn[6]; /* PN of the last fragment if CCMP was used */
+	unsigned int key_color;
 };
 
 
diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index fa10c6142244..d122031e389a 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -648,6 +648,7 @@ int ieee80211_key_link(struct ieee80211_key *key,
 		       struct sta_info *sta)
 {
 	struct ieee80211_local *local = sdata->local;
+	static atomic_t key_color = ATOMIC_INIT(0);
 	struct ieee80211_key *old_key;
 	int idx = key->conf.keyidx;
 	bool pairwise = key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE;
@@ -659,6 +660,12 @@ int ieee80211_key_link(struct ieee80211_key *key,
 	bool delay_tailroom = sdata->vif.type == NL80211_IFTYPE_STATION;
 	int ret;
 
+	/*
+	 * Assign a unique ID to every key so we can easily prevent mixed
+	 * key and fragment cache attacks.
+	 */
+	key->color = atomic_inc_return(&key_color);
+
 	mutex_lock(&sdata->local->key_mtx);
 
 	if (sta && pairwise)
diff --git a/net/mac80211/key.h b/net/mac80211/key.h
index ebdb80b85dc3..d8e187bcb751 100644
--- a/net/mac80211/key.h
+++ b/net/mac80211/key.h
@@ -127,6 +127,8 @@ struct ieee80211_key {
 	} debugfs;
 #endif
 
+	unsigned int color;
+
 	/*
 	 * key config, must be last because it contains key
 	 * material as variable length member
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 9b313c2f7d49..8c126854aa06 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2029,6 +2029,7 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
 			 * next fragment has a sequential PN value.
 			 */
 			entry->check_sequential_pn = true;
+			entry->key_color = rx->key->color;
 			memcpy(entry->last_pn,
 			       rx->key->u.ccmp.rx_pn[queue],
 			       IEEE80211_CCMP_PN_LEN);
@@ -2066,6 +2067,11 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
 
 		if (!requires_sequential_pn(rx, fc))
 			return RX_DROP_UNUSABLE;
+
+		/* Prevent mixed key and fragment cache attacks */
+		if (entry->key_color != rx->key->color)
+			return RX_DROP_UNUSABLE;
+
 		memcpy(pn, entry->last_pn, IEEE80211_CCMP_PN_LEN);
 		for (i = IEEE80211_CCMP_PN_LEN - 1; i >= 0; i--) {
 			pn[i]++;