wifi: iwlwifi: mvm: don't access packet before checking len

Currently in sniffer mode we access pkt fields before checking that
the frame has the length to access it. Fix this by moving the check
to before the access.
Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20221205102808.934da230c698.Ib56f11bbc8978e15d38394336a929cb4996ba39e@changeid

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

@@ -2066,22 +2066,30 @@ void iwl_mvm_rx_monitor_no_data(struct iwl_mvm *mvm, struct napi_struct *napi,
 	struct ieee80211_rx_status *rx_status;
 	struct iwl_rx_packet *pkt = rxb_addr(rxb);
 	struct iwl_rx_no_data *desc = (void *)pkt->data;
-	u32 rssi = le32_to_cpu(desc->rssi);
-	u32 info_type = le32_to_cpu(desc->info) & RX_NO_DATA_INFO_TYPE_MSK;
+	u32 rssi;
+	u32 info_type;
 	struct ieee80211_sta *sta = NULL;
 	struct sk_buff *skb;
-	struct iwl_mvm_rx_phy_data phy_data = {
-		.d0 = desc->phy_info[0],
-		.d1 = desc->phy_info[1],
-		.phy_info = IWL_RX_MPDU_PHY_TSF_OVERLOAD,
-		.gp2_on_air_rise = le32_to_cpu(desc->on_air_rise_time),
-		.rate_n_flags = le32_to_cpu(desc->rate),
-		.energy_a = u32_get_bits(rssi, RX_NO_DATA_CHAIN_A_MSK),
-		.energy_b = u32_get_bits(rssi, RX_NO_DATA_CHAIN_B_MSK),
-		.channel = u32_get_bits(rssi, RX_NO_DATA_CHANNEL_MSK),
-	};
+	struct iwl_mvm_rx_phy_data phy_data;
 	u32 format;
 
+	if (unlikely(test_bit(IWL_MVM_STATUS_IN_HW_RESTART, &mvm->status)))
+		return;
+
+	if (unlikely(iwl_rx_packet_payload_len(pkt) < sizeof(struct iwl_rx_no_data)))
+		return;
+
+	rssi = le32_to_cpu(desc->rssi);
+	info_type = le32_to_cpu(desc->info) & RX_NO_DATA_INFO_TYPE_MSK;
+	phy_data.d0 = desc->phy_info[0];
+	phy_data.d1 = desc->phy_info[1];
+	phy_data.phy_info = IWL_RX_MPDU_PHY_TSF_OVERLOAD;
+	phy_data.gp2_on_air_rise = le32_to_cpu(desc->on_air_rise_time);
+	phy_data.rate_n_flags = le32_to_cpu(desc->rate);
+	phy_data.energy_a = u32_get_bits(rssi, RX_NO_DATA_CHAIN_A_MSK);
+	phy_data.energy_b = u32_get_bits(rssi, RX_NO_DATA_CHAIN_B_MSK);
+	phy_data.channel = u32_get_bits(rssi, RX_NO_DATA_CHANNEL_MSK);
+
 	if (iwl_fw_lookup_notif_ver(mvm->fw, DATA_PATH_GROUP,
 				    RX_NO_DATA_NOTIF, 0) < 2) {
 		IWL_DEBUG_DROP(mvm, "Got an old rate format. Old rate: 0x%x\n",
@@ -2093,12 +2101,6 @@ void iwl_mvm_rx_monitor_no_data(struct iwl_mvm *mvm, struct napi_struct *napi,
 
 	format = phy_data.rate_n_flags & RATE_MCS_MOD_TYPE_MSK;
 
-	if (unlikely(iwl_rx_packet_payload_len(pkt) < sizeof(*desc)))
-		return;
-
-	if (unlikely(test_bit(IWL_MVM_STATUS_IN_HW_RESTART, &mvm->status)))
-		return;
-
 	/* Dont use dev_alloc_skb(), we'll have enough headroom once
 	 * ieee80211_hdr pulled.
 	 */