wifi: iwlwifi: pcie: add size assertions

Ensure that the TX command scratch fits into the buffer
provided by the first TB. It does, of course, but add
some build-time validations in case we touch this code.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230620125813.8f54f2990b92.If19a038dfd633d4601e3d44dd0ff678bc0a851e9@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/intel/iwlwifi/pcie/tx.c

 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
 /*
- * Copyright (C) 2003-2014, 2018-2021 Intel Corporation
+ * Copyright (C) 2003-2014, 2018-2021, 2023 Intel Corporation
  * Copyright (C) 2013-2015 Intel Mobile Communications GmbH
  * Copyright (C) 2016-2017 Intel Deutschland GmbH
  */
@@ -1547,6 +1547,9 @@ int iwl_trans_pcie_tx(struct iwl_trans *trans, struct sk_buff *skb,
 
 	/* there must be data left over for TB1 or this code must be changed */
 	BUILD_BUG_ON(sizeof(struct iwl_tx_cmd) < IWL_FIRST_TB_SIZE);
+	BUILD_BUG_ON(sizeof(struct iwl_cmd_header) +
+		     offsetofend(struct iwl_tx_cmd, scratch) >
+		     IWL_FIRST_TB_SIZE);
 
 	/* map the data for TB1 */
 	tb1_addr = ((u8 *)&dev_cmd->hdr) + IWL_FIRST_TB_SIZE;

drivers/net/wireless/intel/iwlwifi/queue/tx.c

@@ -648,6 +648,13 @@ struct iwl_tfh_tfd *iwl_txq_gen2_build_tfd(struct iwl_trans *trans,
 
 	/* There must be data left over for TB1 or this code must be changed */
 	BUILD_BUG_ON(sizeof(struct iwl_tx_cmd_gen2) < IWL_FIRST_TB_SIZE);
+	BUILD_BUG_ON(sizeof(struct iwl_cmd_header) +
+		     offsetofend(struct iwl_tx_cmd_gen2, dram_info) >
+		     IWL_FIRST_TB_SIZE);
+	BUILD_BUG_ON(sizeof(struct iwl_tx_cmd_gen3) < IWL_FIRST_TB_SIZE);
+	BUILD_BUG_ON(sizeof(struct iwl_cmd_header) +
+		     offsetofend(struct iwl_tx_cmd_gen3, dram_info) >
+		     IWL_FIRST_TB_SIZE);
 
 	memset(tfd, 0, sizeof(*tfd));