mwl8k: fix mwl8k_configure_filter() parameter lifetime issue

mwl8k_configure_filter() passes pointers to total_flags and the
multicast address list to a workqueue function, while there is no
guarantee that those pointers will still be valid by the time the
workqueue function runs.

Solve this by passing total_flags by value, and by passing an
already built multicast address setup command packet to the workqueue
function so that we don't have to look at the multicast address list
itself outside of mwl8k_configure_filter().

Also, since ->configure_filter() can sleep now, wait synchronously
for the worker to finish.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwl8k.c

@@ -1613,38 +1613,39 @@ struct mwl8k_cmd_mac_multicast_adr {
 
 #define MWL8K_ENABLE_RX_MULTICAST 0x000F
 
-static int mwl8k_cmd_mac_multicast_adr(struct ieee80211_hw *hw,
-					int mc_count,
-					struct dev_addr_list *mclist)
+static struct mwl8k_cmd_pkt *
+__mwl8k_cmd_mac_multicast_adr(struct ieee80211_hw *hw,
+			      int mc_count, struct dev_addr_list *mclist)
 {
+	struct mwl8k_priv *priv = hw->priv;
 	struct mwl8k_cmd_mac_multicast_adr *cmd;
-	int index = 0;
-	int rc;
-	int size = sizeof(*cmd) + mc_count * ETH_ALEN;
+	int size;
+	int i;
+
+	if (mc_count > priv->num_mcaddrs)
+		mc_count = priv->num_mcaddrs;
+
+	size = sizeof(*cmd) + mc_count * ETH_ALEN;
 
-	cmd = kzalloc(size, GFP_KERNEL);
+	cmd = kzalloc(size, GFP_ATOMIC);
 	if (cmd == NULL)
-		return -ENOMEM;
+		return NULL;
 
 	cmd->header.code = cpu_to_le16(MWL8K_CMD_MAC_MULTICAST_ADR);
 	cmd->header.length = cpu_to_le16(size);
 	cmd->action = cpu_to_le16(MWL8K_ENABLE_RX_MULTICAST);
 	cmd->numaddr = cpu_to_le16(mc_count);
 
-	while (index < mc_count && mclist) {
+	for (i = 0; i < mc_count && mclist; i++) {
 		if (mclist->da_addrlen != ETH_ALEN) {
-			rc = -EINVAL;
-			goto mwl8k_cmd_mac_multicast_adr_exit;
+			kfree(cmd);
+			return NULL;
 		}
-		memcpy(cmd->addr[index++], mclist->da_addr, ETH_ALEN);
+		memcpy(cmd->addr[i], mclist->da_addr, ETH_ALEN);
 		mclist = mclist->next;
 	}
 
-	rc = mwl8k_post_cmd(hw, &cmd->header);
-
-mwl8k_cmd_mac_multicast_adr_exit:
-	kfree(cmd);
-	return rc;
+	return &cmd->header;
 }
 
 /*
@@ -3091,12 +3092,21 @@ static void mwl8k_bss_info_changed(struct ieee80211_hw *hw,
 		printk(KERN_ERR "%s() timed out\n", __func__);
 }
 
+static u64 mwl8k_prepare_multicast(struct ieee80211_hw *hw,
+				   int mc_count, struct dev_addr_list *mclist)
+{
+	struct mwl8k_cmd_pkt *cmd;
+
+	cmd = __mwl8k_cmd_mac_multicast_adr(hw, mc_count, mclist);
+
+	return (unsigned long)cmd;
+}
+
 struct mwl8k_configure_filter_worker {
 	struct mwl8k_work_struct header;
 	unsigned int changed_flags;
-	unsigned int *total_flags;
-	int mc_count;
-	struct dev_addr_list *mclist;
+	unsigned int total_flags;
+	struct mwl8k_cmd_pkt *multicast_adr_cmd;
 };
 
 #define MWL8K_SUPPORTED_IF_FLAGS	FIF_BCN_PRBRESP_PROMISC
@@ -3105,18 +3115,12 @@ static int mwl8k_configure_filter_wt(struct work_struct *wt)
 {
 	struct mwl8k_configure_filter_worker *worker =
 		(struct mwl8k_configure_filter_worker *)wt;
-
 	struct ieee80211_hw *hw = worker->header.hw;
-	unsigned int changed_flags = worker->changed_flags;
-	unsigned int *total_flags = worker->total_flags;
-	int mc_count = worker->mc_count;
-	struct dev_addr_list *mclist = worker->mclist;
-
 	struct mwl8k_priv *priv = hw->priv;
 	int rc = 0;
 
-	if (changed_flags & FIF_BCN_PRBRESP_PROMISC) {
-		if (*total_flags & FIF_BCN_PRBRESP_PROMISC)
+	if (worker->changed_flags & FIF_BCN_PRBRESP_PROMISC) {
+		if (worker->total_flags & FIF_BCN_PRBRESP_PROMISC)
 			rc = mwl8k_cmd_set_pre_scan(hw);
 		else {
 			u8 *bssid;
@@ -3129,54 +3133,20 @@ static int mwl8k_configure_filter_wt(struct work_struct *wt)
 		}
 	}
 
-	if (rc)
-		goto mwl8k_configure_filter_exit;
-	if (mc_count) {
-		if (mc_count > priv->num_mcaddrs)
-			mc_count = priv->num_mcaddrs;
-
-		rc = mwl8k_cmd_mac_multicast_adr(hw, mc_count, mclist);
-		if (rc)
-			printk(KERN_ERR
-			"%s()Error setting multicast addresses\n",
-			__func__);
-	}
+	if (!rc && worker->multicast_adr_cmd != NULL)
+		rc = mwl8k_post_cmd(hw, worker->multicast_adr_cmd);
+	kfree(worker->multicast_adr_cmd);
 
-mwl8k_configure_filter_exit:
 	return rc;
 }
 
-static u64 mwl8k_prepare_multicast(struct ieee80211_hw *hw,
-				   int mc_count, struct dev_addr_list *mclist)
-{
-	struct mwl8k_configure_filter_worker *worker;
-
-	worker = kzalloc(sizeof(*worker), GFP_ATOMIC);
-
-	if (!worker)
-		return 0;
-
-	/*
-	 * XXX: This is _HORRIBLY_ broken!!
-	 *
-	 *	No locking, the mclist pointer might be invalid as soon as this
-	 *	function returns, something in the list might be invalidated
-	 *	once we get to the worker, etc...
-	 */
-	worker->mc_count = mc_count;
-	worker->mclist = mclist;
-
-	return (u64)worker;
-}
-
 static void mwl8k_configure_filter(struct ieee80211_hw *hw,
 				   unsigned int changed_flags,
 				   unsigned int *total_flags,
 				   u64 multicast)
 {
-
-	struct mwl8k_configure_filter_worker *worker = (void *)multicast;
 	struct mwl8k_priv *priv = hw->priv;
+	struct mwl8k_configure_filter_worker *worker;
 
 	/* Clear unsupported feature flags */
 	*total_flags &= MWL8K_SUPPORTED_IF_FLAGS;
@@ -3184,12 +3154,13 @@ static void mwl8k_configure_filter(struct ieee80211_hw *hw,
 	if (!(changed_flags & MWL8K_SUPPORTED_IF_FLAGS))
 		return;
 
+	worker = kzalloc(sizeof(*worker), GFP_ATOMIC);
 	if (worker == NULL)
 		return;
 
-	worker->header.options = MWL8K_WQ_QUEUE_ONLY | MWL8K_WQ_TX_WAIT_EMPTY;
 	worker->changed_flags = changed_flags;
-	worker->total_flags = total_flags;
+	worker->total_flags = *total_flags;
+	worker->multicast_adr_cmd = (void *)(unsigned long)multicast;
 
 	mwl8k_queue_work(hw, &worker->header, priv->config_wq,
 			 mwl8k_configure_filter_wt);