Commit 5d02b3cd authored by Linus Lüssing's avatar Linus Lüssing Committed by Marek Lindner
Browse files

batman-adv: Make bat_priv->curr_gw an rcu protected pointer 



The rcu protected macros rcu_dereference() and rcu_assign_pointer()
for the bat_priv->curr_gw need to be used, as well as spin/rcu locking.

Otherwise we might end up using a curr_gw pointer pointing to already
freed memory.

Reported-by: default avatarSven Eckelmann <sven@narfation.org>
Signed-off-by: default avatarLinus Lüssing <linus.luessing@ascom.ch>
Signed-off-by: default avatarMarek Lindner <lindner_marek@yahoo.de>
parent f3e0008f

net/batman-adv/gateway_client.c

+70 −30
Original line number Diff line number Diff line
@@ -44,19 +44,29 @@ static void gw_node_free_ref(struct gw_node *gw_node) 


void *gw_get_selected(struct bat_priv *bat_priv)

{

	struct gw_node *curr_gateway_tmp = bat_priv->curr_gw;

	struct gw_node *curr_gateway_tmp;

	struct orig_node *orig_node = NULL;



	rcu_read_lock();

	curr_gateway_tmp = rcu_dereference(bat_priv->curr_gw);

	if (!curr_gateway_tmp)

		return NULL;

		goto out;



	orig_node = curr_gateway_tmp->orig_node;



	return curr_gateway_tmp->orig_node;

out:

	rcu_read_unlock();

	return orig_node;

}



void gw_deselect(struct bat_priv *bat_priv)

{

	struct gw_node *gw_node = bat_priv->curr_gw;

	struct gw_node *gw_node;



	bat_priv->curr_gw = NULL;

	spin_lock_bh(&bat_priv->gw_list_lock);

	gw_node = rcu_dereference(bat_priv->curr_gw);

	rcu_assign_pointer(bat_priv->curr_gw, NULL);

	spin_unlock_bh(&bat_priv->gw_list_lock);



	if (gw_node)

		gw_node_free_ref(gw_node);
@@ -64,12 +74,15 @@ void gw_deselect(struct bat_priv *bat_priv) 


static void gw_select(struct bat_priv *bat_priv, struct gw_node *new_gw_node)

{

	struct gw_node *curr_gw_node = bat_priv->curr_gw;

	struct gw_node *curr_gw_node;



	if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount))

		new_gw_node = NULL;



	bat_priv->curr_gw = new_gw_node;

	spin_lock_bh(&bat_priv->gw_list_lock);

	curr_gw_node = rcu_dereference(bat_priv->curr_gw);

	rcu_assign_pointer(bat_priv->curr_gw, new_gw_node);

	spin_unlock_bh(&bat_priv->gw_list_lock);



	if (curr_gw_node)

		gw_node_free_ref(curr_gw_node);
@@ -78,7 +91,7 @@ static void gw_select(struct bat_priv *bat_priv, struct gw_node *new_gw_node) 
void gw_election(struct bat_priv *bat_priv)

{

	struct hlist_node *node;

	struct gw_node *gw_node, *curr_gw_tmp = NULL;

	struct gw_node *gw_node, *curr_gw, *curr_gw_tmp = NULL;

	uint8_t max_tq = 0;

	uint32_t max_gw_factor = 0, tmp_gw_factor = 0;

	int down, up;
@@ -92,19 +105,23 @@ void gw_election(struct bat_priv *bat_priv) 
	if (atomic_read(&bat_priv->gw_mode) != GW_MODE_CLIENT)

		return;



	if (bat_priv->curr_gw)

	rcu_read_lock();

	curr_gw = rcu_dereference(bat_priv->curr_gw);

	if (curr_gw) {

		rcu_read_unlock();

		return;

	}



	rcu_read_lock();

	if (hlist_empty(&bat_priv->gw_list)) {

		rcu_read_unlock();



		if (bat_priv->curr_gw) {

		if (curr_gw) {

			rcu_read_unlock();

			bat_dbg(DBG_BATMAN, bat_priv,

				"Removing selected gateway - "

				"no gateway in range\n");

			gw_deselect(bat_priv);

		}

		} else

			rcu_read_unlock();



		return;

	}
@@ -153,12 +170,12 @@ void gw_election(struct bat_priv *bat_priv) 
			max_gw_factor = tmp_gw_factor;

	}



	if (bat_priv->curr_gw != curr_gw_tmp) {

		if ((bat_priv->curr_gw) && (!curr_gw_tmp))

	if (curr_gw != curr_gw_tmp) {

		if ((curr_gw) && (!curr_gw_tmp))

			bat_dbg(DBG_BATMAN, bat_priv,

				"Removing selected gateway - "

				"no gateway in range\n");

		else if ((!bat_priv->curr_gw) && (curr_gw_tmp))

		else if ((!curr_gw) && (curr_gw_tmp))

			bat_dbg(DBG_BATMAN, bat_priv,

				"Adding route to gateway %pM "

				"(gw_flags: %i, tq: %i)\n",
@@ -181,31 +198,35 @@ void gw_election(struct bat_priv *bat_priv) 


void gw_check_election(struct bat_priv *bat_priv, struct orig_node *orig_node)

{

	struct gw_node *curr_gateway_tmp = bat_priv->curr_gw;

	struct gw_node *curr_gateway_tmp;

	uint8_t gw_tq_avg, orig_tq_avg;



	rcu_read_lock();

	curr_gateway_tmp = rcu_dereference(bat_priv->curr_gw);

	if (!curr_gateway_tmp)

		return;

		goto out_rcu;



	if (!curr_gateway_tmp->orig_node)

		goto deselect;

		goto deselect_rcu;



	if (!curr_gateway_tmp->orig_node->router)

		goto deselect;

		goto deselect_rcu;



	/* this node already is the gateway */

	if (curr_gateway_tmp->orig_node == orig_node)

		return;

		goto out_rcu;



	if (!orig_node->router)

		return;

		goto out_rcu;



	gw_tq_avg = curr_gateway_tmp->orig_node->router->tq_avg;

	rcu_read_unlock();



	orig_tq_avg = orig_node->router->tq_avg;



	/* the TQ value has to be better */

	if (orig_tq_avg < gw_tq_avg)

		return;

		goto out;



	/**

	 * if the routing class is greater than 3 the value tells us how much
@@ -213,15 +234,23 @@ void gw_check_election(struct bat_priv *bat_priv, struct orig_node *orig_node) 
	 **/

	if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&

	    (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))

		return;

		goto out;



	bat_dbg(DBG_BATMAN, bat_priv,

		"Restarting gateway selection: better gateway found (tq curr: "

		"%i, tq new: %i)\n",

		gw_tq_avg, orig_tq_avg);

	goto deselect;



out_rcu:

	rcu_read_unlock();

	goto out;

deselect_rcu:

	rcu_read_unlock();

deselect:

	gw_deselect(bat_priv);

out:

	return;

}



static void gw_node_add(struct bat_priv *bat_priv,
@@ -278,7 +307,7 @@ void gw_node_update(struct bat_priv *bat_priv, 
				"Gateway %pM removed from gateway list\n",

				orig_node->orig);



			if (gw_node == bat_priv->curr_gw) {

			if (gw_node == rcu_dereference(bat_priv->curr_gw)) {

				rcu_read_unlock();

				gw_deselect(bat_priv);

				return;
@@ -316,7 +345,7 @@ void gw_node_purge(struct bat_priv *bat_priv) 
		    atomic_read(&bat_priv->mesh_state) == MESH_ACTIVE)

			continue;



		if (bat_priv->curr_gw == gw_node)

		if (rcu_dereference(bat_priv->curr_gw) == gw_node)

			gw_deselect(bat_priv);



		hlist_del_rcu(&gw_node->list);
@@ -330,12 +359,16 @@ void gw_node_purge(struct bat_priv *bat_priv) 
static int _write_buffer_text(struct bat_priv *bat_priv,

			      struct seq_file *seq, struct gw_node *gw_node)

{

	int down, up;

	struct gw_node *curr_gw;

	int down, up, ret;



	gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags, &down, &up);



	return seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",

		       (bat_priv->curr_gw == gw_node ? "=>" : "  "),

	rcu_read_lock();

	curr_gw = rcu_dereference(bat_priv->curr_gw);



	ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",

		       (curr_gw == gw_node ? "=>" : "  "),

		       gw_node->orig_node->orig,

		       gw_node->orig_node->router->tq_avg,

		       gw_node->orig_node->router->addr,
@@ -345,6 +378,9 @@ static int _write_buffer_text(struct bat_priv *bat_priv, 
		       (down > 2048 ? "MBit" : "KBit"),

		       (up > 2048 ? up / 1024 : up),

		       (up > 2048 ? "MBit" : "KBit"));



	rcu_read_unlock();

	return ret;

}



int gw_client_seq_print_text(struct seq_file *seq, void *offset)
@@ -465,8 +501,12 @@ int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb) 
	if (atomic_read(&bat_priv->gw_mode) == GW_MODE_SERVER)

		return -1;



	if (!bat_priv->curr_gw)

	rcu_read_lock();

	if (!rcu_dereference(bat_priv->curr_gw)) {

		rcu_read_unlock();

		return 0;

	}

	rcu_read_unlock();



	return 1;

}

net/batman-adv/types.h

+2 −2
Original line number Diff line number Diff line
@@ -162,7 +162,7 @@ struct bat_priv { 
	spinlock_t forw_bcast_list_lock; /* protects  */

	spinlock_t hna_lhash_lock; /* protects hna_local_hash */

	spinlock_t hna_ghash_lock; /* protects hna_global_hash */

	spinlock_t gw_list_lock; /* protects gw_list */

	spinlock_t gw_list_lock; /* protects gw_list and curr_gw */

	spinlock_t vis_hash_lock; /* protects vis_hash */

	spinlock_t vis_list_lock; /* protects vis_info::recv_list */

	spinlock_t softif_neigh_lock; /* protects soft-interface neigh list */
@@ -171,7 +171,7 @@ struct bat_priv { 
	struct delayed_work hna_work;

	struct delayed_work orig_work;

	struct delayed_work vis_work;

	struct gw_node *curr_gw;

	struct gw_node __rcu *curr_gw;  /* rcu protected pointer */

	struct vis_info *my_vis_info;

};

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