hostap: Protect against initialization interrupt

Use an irq spinlock to hold off the IRQ handler until
enough early card init is complete such that the handler
can run without faulting.
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Cc: stable@kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/hostap/hostap_cs.c

@@ -594,6 +594,7 @@ static int prism2_config(struct pcmcia_device *link)
 	local_info_t *local;
 	int ret = 1;
 	struct hostap_cs_priv *hw_priv;
+	unsigned long flags;
 
 	PDEBUG(DEBUG_FLOW, "prism2_config()\n");
 
@@ -625,9 +626,15 @@ static int prism2_config(struct pcmcia_device *link)
 	local->hw_priv = hw_priv;
 	hw_priv->link = link;
 
+	/*
+	 * Make sure the IRQ handler cannot proceed until at least
+	 * dev->base_addr is initialized.
+	 */
+	spin_lock_irqsave(&local->irq_init_lock, flags);
+
 	ret = pcmcia_request_irq(link, prism2_interrupt);
 	if (ret)
-		goto failed;
+		goto failed_unlock;
 
 	/*
 	 * This actually configures the PCMCIA socket -- setting up
@@ -636,11 +643,13 @@ static int prism2_config(struct pcmcia_device *link)
 	 */
 	ret = pcmcia_request_configuration(link, &link->conf);
 	if (ret)
-		goto failed;
+		goto failed_unlock;
 
 	dev->irq = link->irq;
 	dev->base_addr = link->io.BasePort1;
 
+	spin_unlock_irqrestore(&local->irq_init_lock, flags);
+
 	/* Finally, report what we've done */
 	printk(KERN_INFO "%s: index 0x%02x: ",
 	       dev_info, link->conf.ConfigIndex);
@@ -667,6 +676,8 @@ static int prism2_config(struct pcmcia_device *link)
 
 	return ret;
 
+ failed_unlock:
+	 spin_unlock_irqrestore(&local->irq_init_lock, flags);
  failed:
 	kfree(hw_priv);
 	prism2_release((u_long)link);

drivers/net/wireless/hostap/hostap_hw.c

@@ -2621,6 +2621,18 @@ static irqreturn_t prism2_interrupt(int irq, void *dev_id)
 	iface = netdev_priv(dev);
 	local = iface->local;
 
+	/* Detect early interrupt before driver is fully configued */
+	spin_lock(&local->irq_init_lock);
+	if (!dev->base_addr) {
+		if (net_ratelimit()) {
+			printk(KERN_DEBUG "%s: Interrupt, but dev not configured\n",
+			       dev->name);
+		}
+		spin_unlock(&local->irq_init_lock);
+		return IRQ_HANDLED;
+	}
+	spin_unlock(&local->irq_init_lock);
+
 	prism2_io_debug_add(dev, PRISM2_IO_DEBUG_CMD_INTERRUPT, 0, 0);
 
 	if (local->func->card_present && !local->func->card_present(local)) {
@@ -3138,6 +3150,7 @@ prism2_init_local_data(struct prism2_helper_functions *funcs, int card_idx,
 	spin_lock_init(&local->cmdlock);
 	spin_lock_init(&local->baplock);
 	spin_lock_init(&local->lock);
+	spin_lock_init(&local->irq_init_lock);
 	mutex_init(&local->rid_bap_mtx);
 
 	if (card_idx < 0 || card_idx >= MAX_PARM_DEVICES)

drivers/net/wireless/hostap/hostap_wlan.h

@@ -654,7 +654,7 @@ struct local_info {
 	rwlock_t iface_lock; /* hostap_interfaces read lock; use write lock
 			      * when removing entries from the list.
 			      * TX and RX paths can use read lock. */
-	spinlock_t cmdlock, baplock, lock;
+	spinlock_t cmdlock, baplock, lock, irq_init_lock;
 	struct mutex rid_bap_mtx;
 	u16 infofid; /* MAC buffer id for info frame */
 	/* txfid, intransmitfid, next_txtid, and next_alloc are protected by