iwlwifi: mvm: check return value of rs_rate_from_ucode_rate()

The rs_rate_from_ucode_rate() function may return -EINVAL if the rate
is invalid, but none of the callsites check for the error, potentially
making us access arrays with index IWL_RATE_INVALID, which is larger
than the arrays, causing an out-of-bounds access.  This will trigger
KASAN warnings, such as the one reported in the bugzilla issue
mentioned below.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=200659

Cc: stable@vger.kernel.org
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/intel/iwlwifi/mvm/rs.c

@@ -1239,7 +1239,11 @@ void iwl_mvm_rs_tx_status(struct iwl_mvm *mvm, struct ieee80211_sta *sta,
 	    !(info->flags & IEEE80211_TX_STAT_AMPDU))
 		return;
 
-	rs_rate_from_ucode_rate(tx_resp_hwrate, info->band, &tx_resp_rate);
+	if (rs_rate_from_ucode_rate(tx_resp_hwrate, info->band,
+				    &tx_resp_rate)) {
+		WARN_ON_ONCE(1);
+		return;
+	}
 
 #ifdef CONFIG_MAC80211_DEBUGFS
 	/* Disable last tx check if we are debugging with fixed rate but
@@ -1290,7 +1294,10 @@ void iwl_mvm_rs_tx_status(struct iwl_mvm *mvm, struct ieee80211_sta *sta,
 	 */
 	table = &lq_sta->lq;
 	lq_hwrate = le32_to_cpu(table->rs_table[0]);
-	rs_rate_from_ucode_rate(lq_hwrate, info->band, &lq_rate);
+	if (rs_rate_from_ucode_rate(lq_hwrate, info->band, &lq_rate)) {
+		WARN_ON_ONCE(1);
+		return;
+	}
 
 	/* Here we actually compare this rate to the latest LQ command */
 	if (lq_color != LQ_FLAG_COLOR_GET(table->flags)) {
@@ -1392,8 +1399,12 @@ void iwl_mvm_rs_tx_status(struct iwl_mvm *mvm, struct ieee80211_sta *sta,
 		/* Collect data for each rate used during failed TX attempts */
 		for (i = 0; i <= retries; ++i) {
 			lq_hwrate = le32_to_cpu(table->rs_table[i]);
-			rs_rate_from_ucode_rate(lq_hwrate, info->band,
-						&lq_rate);
+			if (rs_rate_from_ucode_rate(lq_hwrate, info->band,
+						    &lq_rate)) {
+				WARN_ON_ONCE(1);
+				return;
+			}
+
 			/*
 			 * Only collect stats if retried rate is in the same RS
 			 * table as active/search.
@@ -3260,7 +3271,10 @@ static void rs_build_rates_table_from_fixed(struct iwl_mvm *mvm,
 	for (i = 0; i < num_rates; i++)
 		lq_cmd->rs_table[i] = ucode_rate_le32;
 
-	rs_rate_from_ucode_rate(ucode_rate, band, &rate);
+	if (rs_rate_from_ucode_rate(ucode_rate, band, &rate)) {
+		WARN_ON_ONCE(1);
+		return;
+	}
 
 	if (is_mimo(&rate))
 		lq_cmd->mimo_delim = num_rates - 1;