mwifiex: fix NULL pointer dereference during suspend

This patch fixes below NULL pointer dereference observed in suspend
stress test. When scan is cancelled during system suspend, we may end
up aceesing "priv->scan_request" in corner case.

[ 3035.304682] BUG: KASAN: null-ptr-deref on address 0000000000000008
[ 3035.304704] Read of size 4 by task ksdioirqd/mmc2/1183
[ 3035.304744] CPU: 0 PID: 1183 Comm: ksdioirqd/mmc2 Tainted: G        W      3.18.0 #1169
[ 3035.304772] Call trace:
[ 3035.304825] [<ffffffc00020a520>] dump_backtrace+0x0/0x190
[ 3035.304864] [<ffffffc00020a6cc>] show_stack+0x1c/0x28
[ 3035.304901] [<ffffffc000b36db8>] dump_stack+0xa0/0xf8
[ 3035.304940] [<ffffffc00039c494>] kasan_report+0x120/0x4fc
[ 3035.304975] [<ffffffc00039b6b4>] __asan_load4+0x20/0x80
[ 3035.305546] [<ffffffbffc1f5aec>] mwifiex_check_next_scan_command+0x1a4/0x588 [mwifiex]
[ 3035.306091] [<ffffffbffc1f7aec>] mwifiex_handle_event_ext_scan_report+0x304/0x370 [mwifiex]
[ 3035.306735] [<ffffffbffc206bb8>] mwifiex_process_sta_event+0x6c0/0xf10 [mwifiex]
[ 3035.307200] [<ffffffbffc1e609c>] mwifiex_process_event+0x2f4/0x358 [mwifiex]
[ 3035.307612] [<ffffffbffc1e25c8>] mwifiex_main_process+0x3cc/0x80c [mwifiex]
[ 3035.307737] [<ffffffbffc2523a0>] mwifiex_sdio_interrupt+0x198/0x1c0 [mwifiex_sdio]
[ 3035.307785] [<ffffffc0008d9250>] process_sdio_pending_irqs+0x15c/0x1d4
[ 3035.307826] [<ffffffc0008d93f0>] sdio_irq_thread+0xd8/0x288

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/mwifiex/cfg80211.c

@@ -3316,6 +3316,7 @@ static int mwifiex_cfg80211_suspend(struct wiphy *wiphy,
 	struct mwifiex_private *sta_priv =
 			mwifiex_get_priv(adapter, MWIFIEX_BSS_ROLE_STA);
 
+	sta_priv->scan_aborting = true;
 	for (i = 0; i < adapter->priv_num; i++) {
 		priv = adapter->priv[i];
 		mwifiex_abort_cac(priv);
@@ -3344,19 +3345,21 @@ static int mwifiex_cfg80211_suspend(struct wiphy *wiphy,
 	if (!wowlan) {
 		mwifiex_dbg(adapter, ERROR,
 			    "None of the WOWLAN triggers enabled\n");
-		return 0;
+		ret = 0;
+		goto done;
 	}
 
 	if (!sta_priv->media_connected && !wowlan->nd_config) {
 		mwifiex_dbg(adapter, ERROR,
 			    "Can not configure WOWLAN in disconnected state\n");
-		return 0;
+		ret = 0;
+		goto done;
 	}
 
 	ret = mwifiex_set_mef_filter(sta_priv, wowlan);
 	if (ret) {
 		mwifiex_dbg(adapter, ERROR, "Failed to set MEF filter\n");
-		return ret;
+		goto done;
 	}
 
 	memset(&hs_cfg, 0, sizeof(hs_cfg));
@@ -3379,12 +3382,11 @@ static int mwifiex_cfg80211_suspend(struct wiphy *wiphy,
 	hs_cfg.gap = adapter->hs_cfg.gap;
 	ret = mwifiex_set_hs_params(sta_priv, HostCmd_ACT_GEN_SET,
 				    MWIFIEX_SYNC_CMD, &hs_cfg);
-	if (ret) {
-		mwifiex_dbg(adapter, ERROR,
-			    "Failed to set HS params\n");
-		return ret;
-	}
+	if (ret)
+		mwifiex_dbg(adapter, ERROR, "Failed to set HS params\n");
 
+done:
+	sta_priv->scan_aborting = false;
 	return ret;
 }
 

drivers/net/wireless/marvell/mwifiex/scan.c

@@ -1896,7 +1896,8 @@ mwifiex_active_scan_req_for_passive_chan(struct mwifiex_private *priv)
 	u8 id = 0;
 	struct mwifiex_user_scan_cfg  *user_scan_cfg;
 
-	if (adapter->active_scan_triggered || !priv->scan_request) {
+	if (adapter->active_scan_triggered || !priv->scan_request ||
+	    priv->scan_aborting) {
 		adapter->active_scan_triggered = false;
 		return 0;
 	}

drivers/net/wireless/marvell/mwifiex/sta_event.c

@@ -708,7 +708,7 @@ int mwifiex_process_sta_event(struct mwifiex_private *priv)
 
 	case EVENT_EXT_SCAN_REPORT:
 		mwifiex_dbg(adapter, EVENT, "event: EXT_SCAN Report\n");
-		if (adapter->ext_scan)
+		if (adapter->ext_scan && !priv->scan_aborting)
 			ret = mwifiex_handle_event_ext_scan_report(priv,
 						adapter->event_skb->data);