wifi: iwlwifi: calib: Refactor iwl_calib_result usage for clarity

In preparation for FORTIFY_SOURCE performing run-time destination buffer
bounds checking for memcpy(), refactor the use of struct iwl_calib_result:

- Have struct iwl_calib_result contain struct iwl_calib_cmd since
  functions expect to operate on the "data" flex array in "cmd", which
  follows the "hdr" member.
- Switch argument passing around to use struct iwl_calib_cmd instead of
  struct iwl_calib_hdr to prepare functions to see the "data" member.
- Change iwl_calib_set()'s "len" argument to a size_t since it is always
  unsigned and is normally receiving the output of sizeof().
- Add an explicit length sanity check in iwl_calib_set().
- Adjust the memcpy() to avoid copying across the now visible composite
  flex array structure.

This avoids the future run-time warning:

  memcpy: detected field-spanning write (size 8) of single field "&res->hdr" (size 4)

Cc: Luca Coelho <[email protected]>
Cc: Kalle Valo <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Lee Jones <[email protected]>
Cc: Johannes Berg <[email protected]>
Cc: [email protected]
Cc: [email protected]
Reported-by: Andy Lavr <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Kalle Valo <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/net/wireless/intel/iwlwifi/dvm/ucode.c b/drivers/net/wireless/intel/iwlwifi/dvm/ucode.c
index 4b27a53d0bb4..bb13ca5d666c 100644
--- a/drivers/net/wireless/intel/iwlwifi/dvm/ucode.c
+++ b/drivers/net/wireless/intel/iwlwifi/dvm/ucode.c
@@ -356,18 +356,18 @@ static bool iwlagn_wait_calib(struct iwl_notif_wait_data *notif_wait,
 			      struct iwl_rx_packet *pkt, void *data)
 {
 	struct iwl_priv *priv = data;
-	struct iwl_calib_hdr *hdr;
+	struct iwl_calib_cmd *cmd;
 
 	if (pkt->hdr.cmd != CALIBRATION_RES_NOTIFICATION) {
 		WARN_ON(pkt->hdr.cmd != CALIBRATION_COMPLETE_NOTIFICATION);
 		return true;
 	}
 
-	hdr = (struct iwl_calib_hdr *)pkt->data;
+	cmd = (struct iwl_calib_cmd *)pkt->data;
 
-	if (iwl_calib_set(priv, hdr, iwl_rx_packet_payload_len(pkt)))
+	if (iwl_calib_set(priv, cmd, iwl_rx_packet_payload_len(pkt)))
 		IWL_ERR(priv, "Failed to record calibration data %d\n",
-			hdr->op_code);
+			cmd->hdr.op_code);
 
 	return false;
 }