mwifiex: store mwifiex_ds_misc_subsc_evt in mwifiex_private

Since mwifiex_ds_misc_subsc_evt is used in an asynchronous case,
store the structure in the long-lived mwifiex_private instead of
on the calling stack.

This fixes a problem where the response of the asynchronous
operation would corrupt a stack frame potentially in use by
a different thread.

Signed-off-by: Jeff Disher <disher@chromium.org>
Reviewed-by: Sam Leffler <sleffler@chromium.org>
Tested-by: Jeff Disher <disher@chromium.org>
Acked-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/main.h

@@ -484,6 +484,7 @@ struct mwifiex_private {
 	s32 cqm_rssi_thold;
 	u32 cqm_rssi_hyst;
 	u8 subsc_evt_rssi_state;
+	struct mwifiex_ds_misc_subsc_evt async_subsc_evt_storage;
 	struct mwifiex_ie mgmt_ie[MAX_MGMT_IE_INDEX];
 	u16 beacon_idx;
 	u16 proberesp_idx;

drivers/net/wireless/mwifiex/sta_cmdresp.c

@@ -123,7 +123,8 @@ static int mwifiex_ret_802_11_rssi_info(struct mwifiex_private *priv,
 {
 	struct host_cmd_ds_802_11_rssi_info_rsp *rssi_info_rsp =
 						&resp->params.rssi_info_rsp;
-	struct mwifiex_ds_misc_subsc_evt subsc_evt;
+	struct mwifiex_ds_misc_subsc_evt *subsc_evt =
+						&priv->async_subsc_evt_storage;
 
 	priv->data_rssi_last = le16_to_cpu(rssi_info_rsp->data_rssi_last);
 	priv->data_nf_last = le16_to_cpu(rssi_info_rsp->data_nf_last);
@@ -140,26 +141,27 @@ static int mwifiex_ret_802_11_rssi_info(struct mwifiex_private *priv,
 	if (priv->subsc_evt_rssi_state == EVENT_HANDLED)
 		return 0;
 
+	memset(subsc_evt, 0x00, sizeof(struct mwifiex_ds_misc_subsc_evt));
+
 	/* Resubscribe low and high rssi events with new thresholds */
-	memset(&subsc_evt, 0x00, sizeof(struct mwifiex_ds_misc_subsc_evt));
-	subsc_evt.events = BITMASK_BCN_RSSI_LOW | BITMASK_BCN_RSSI_HIGH;
-	subsc_evt.action = HostCmd_ACT_BITWISE_SET;
+	subsc_evt->events = BITMASK_BCN_RSSI_LOW | BITMASK_BCN_RSSI_HIGH;
+	subsc_evt->action = HostCmd_ACT_BITWISE_SET;
 	if (priv->subsc_evt_rssi_state == RSSI_LOW_RECVD) {
-		subsc_evt.bcn_l_rssi_cfg.abs_value = abs(priv->bcn_rssi_avg -
+		subsc_evt->bcn_l_rssi_cfg.abs_value = abs(priv->bcn_rssi_avg -
 				priv->cqm_rssi_hyst);
-		subsc_evt.bcn_h_rssi_cfg.abs_value = abs(priv->cqm_rssi_thold);
+		subsc_evt->bcn_h_rssi_cfg.abs_value = abs(priv->cqm_rssi_thold);
 	} else if (priv->subsc_evt_rssi_state == RSSI_HIGH_RECVD) {
-		subsc_evt.bcn_l_rssi_cfg.abs_value = abs(priv->cqm_rssi_thold);
-		subsc_evt.bcn_h_rssi_cfg.abs_value = abs(priv->bcn_rssi_avg +
+		subsc_evt->bcn_l_rssi_cfg.abs_value = abs(priv->cqm_rssi_thold);
+		subsc_evt->bcn_h_rssi_cfg.abs_value = abs(priv->bcn_rssi_avg +
 				priv->cqm_rssi_hyst);
 	}
-	subsc_evt.bcn_l_rssi_cfg.evt_freq = 1;
-	subsc_evt.bcn_h_rssi_cfg.evt_freq = 1;
+	subsc_evt->bcn_l_rssi_cfg.evt_freq = 1;
+	subsc_evt->bcn_h_rssi_cfg.evt_freq = 1;
 
 	priv->subsc_evt_rssi_state = EVENT_HANDLED;
 
 	mwifiex_send_cmd_async(priv, HostCmd_CMD_802_11_SUBSCRIBE_EVENT,
-			       0, 0, &subsc_evt);
+			       0, 0, subsc_evt);
 
 	return 0;
 }