Merge branch 'ax25-fixes'

Duoming Zhou says:

====================
ax25: fix NPD and UAF bugs when detaching ax25 device

There are NPD and UAF bugs when detaching ax25 device, we
use lock and refcount to mitigate these bugs.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

Author: davem330

include/net/ax25.h

@@ -239,6 +239,7 @@ typedef struct ax25_dev {
 #if defined(CONFIG_AX25_DAMA_SLAVE) || defined(CONFIG_AX25_DAMA_MASTER)
 	ax25_dama_info		dama;
 #endif
+	refcount_t		refcount;
 } ax25_dev;
 
 typedef struct ax25_cb {
@@ -293,6 +294,15 @@ static __inline__ void ax25_cb_put(ax25_cb *ax25)
 	}
 }
 
+#define ax25_dev_hold(__ax25_dev) \
+	refcount_inc(&((__ax25_dev)->refcount))
+
+static __inline__ void ax25_dev_put(ax25_dev *ax25_dev)
+{
+	if (refcount_dec_and_test(&ax25_dev->refcount)) {
+		kfree(ax25_dev);
+	}
+}
 static inline __be16 ax25_type_trans(struct sk_buff *skb, struct net_device *dev)
 {
 	skb->dev      = dev;

net/ax25/af_ax25.c

@@ -77,6 +77,7 @@ static void ax25_kill_by_device(struct net_device *dev)
 {
 	ax25_dev *ax25_dev;
 	ax25_cb *s;
+	struct sock *sk;
 
 	if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
 		return;
@@ -85,13 +86,16 @@ static void ax25_kill_by_device(struct net_device *dev)
 again:
 	ax25_for_each(s, &ax25_list) {
 		if (s->ax25_dev == ax25_dev) {
+			sk = s->sk;
+			sock_hold(sk);
 			spin_unlock_bh(&ax25_list_lock);
-			lock_sock(s->sk);
+			lock_sock(sk);
 			s->ax25_dev = NULL;
-			release_sock(s->sk);
+			ax25_dev_put(ax25_dev);
+			release_sock(sk);
 			ax25_disconnect(s, ENETUNREACH);
 			spin_lock_bh(&ax25_list_lock);
-
+			sock_put(sk);
 			/* The entry could have been deleted from the
 			 * list meanwhile and thus the next pointer is
 			 * no longer valid.  Play it safe and restart
@@ -436,6 +440,7 @@ static int ax25_ctl_ioctl(const unsigned int cmd, void __user *arg)
 	  }
 
 out_put:
+	ax25_dev_put(ax25_dev);
 	ax25_cb_put(ax25);
 	return ret;
 

net/ax25/ax25_dev.c

@@ -37,6 +37,7 @@ ax25_dev *ax25_addr_ax25dev(ax25_address *addr)
 	for (ax25_dev = ax25_dev_list; ax25_dev != NULL; ax25_dev = ax25_dev->next)
 		if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) == 0) {
 			res = ax25_dev;
+			ax25_dev_hold(ax25_dev);
 		}
 	spin_unlock_bh(&ax25_dev_lock);
 
@@ -56,6 +57,7 @@ void ax25_dev_device_up(struct net_device *dev)
 		return;
 	}
 
+	refcount_set(&ax25_dev->refcount, 1);
 	dev->ax25_ptr     = ax25_dev;
 	ax25_dev->dev     = dev;
 	dev_hold_track(dev, &ax25_dev->dev_tracker, GFP_ATOMIC);
@@ -83,6 +85,7 @@ void ax25_dev_device_up(struct net_device *dev)
 	spin_lock_bh(&ax25_dev_lock);
 	ax25_dev->next = ax25_dev_list;
 	ax25_dev_list  = ax25_dev;
+	ax25_dev_hold(ax25_dev);
 	spin_unlock_bh(&ax25_dev_lock);
 
 	ax25_register_dev_sysctl(ax25_dev);
@@ -112,27 +115,30 @@ void ax25_dev_device_down(struct net_device *dev)
 
 	if ((s = ax25_dev_list) == ax25_dev) {
 		ax25_dev_list = s->next;
+		ax25_dev_put(ax25_dev);
 		spin_unlock_bh(&ax25_dev_lock);
 		dev->ax25_ptr = NULL;
 		dev_put_track(dev, &ax25_dev->dev_tracker);
-		kfree(ax25_dev);
+		ax25_dev_put(ax25_dev);
 		return;
 	}
 
 	while (s != NULL && s->next != NULL) {
 		if (s->next == ax25_dev) {
 			s->next = ax25_dev->next;
+			ax25_dev_put(ax25_dev);
 			spin_unlock_bh(&ax25_dev_lock);
 			dev->ax25_ptr = NULL;
 			dev_put_track(dev, &ax25_dev->dev_tracker);
-			kfree(ax25_dev);
+			ax25_dev_put(ax25_dev);
 			return;
 		}
 
 		s = s->next;
 	}
 	spin_unlock_bh(&ax25_dev_lock);
 	dev->ax25_ptr = NULL;
+	ax25_dev_put(ax25_dev);
 }
 
 int ax25_fwd_ioctl(unsigned int cmd, struct ax25_fwd_struct *fwd)
@@ -149,6 +155,7 @@ int ax25_fwd_ioctl(unsigned int cmd, struct ax25_fwd_struct *fwd)
 		if (ax25_dev->forward != NULL)
 			return -EINVAL;
 		ax25_dev->forward = fwd_dev->dev;
+		ax25_dev_put(fwd_dev);
 		break;
 
 	case SIOCAX25DELFWD:
@@ -161,6 +168,7 @@ int ax25_fwd_ioctl(unsigned int cmd, struct ax25_fwd_struct *fwd)
 		return -EINVAL;
 	}
 
+	ax25_dev_put(ax25_dev);
 	return 0;
 }
 

net/ax25/ax25_route.c

@@ -116,6 +116,7 @@ static int __must_check ax25_rt_add(struct ax25_routes_struct *route)
 	ax25_rt->dev          = ax25_dev->dev;
 	ax25_rt->digipeat     = NULL;
 	ax25_rt->ip_mode      = ' ';
+	ax25_dev_put(ax25_dev);
 	if (route->digi_count != 0) {
 		if ((ax25_rt->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
 			write_unlock_bh(&ax25_route_lock);
@@ -172,6 +173,7 @@ static int ax25_rt_del(struct ax25_routes_struct *route)
 			}
 		}
 	}
+	ax25_dev_put(ax25_dev);
 	write_unlock_bh(&ax25_route_lock);
 
 	return 0;
@@ -214,6 +216,7 @@ static int ax25_rt_opt(struct ax25_route_opt_struct *rt_option)
 	}
 
 out:
+	ax25_dev_put(ax25_dev);
 	write_unlock_bh(&ax25_route_lock);
 	return err;
 }