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Staging: batman-adv: count batman_if list queries as reference

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The return of get_batman_if_by_netdev and get_active_batman_if leaks a
pointer from the rcu protected list of interfaces. We must protect it to
prevent a too early release of the memory. Those functions must increase
the reference counter before rcu_read_unlock or it may be to late to
prevent a free.

hardif_add_interface must also increase the reference count for the
returned batman_if to make the behaviour consistent.

Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Sven Eckelmann 2010-09-18 21:01:20 +02:00 committed by Greg Kroah-Hartman
parent 47f621dddc
commit 399fb5b445
3 changed files with 56 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/staging/batman-adv/TODO
View File

@ -1,7 +1,3 @@
* Rework usage of RCU
- don't leak pointers from rcu out of rcu critical area which may
get freed
- go through Documentation/RCU/checklist.txt
* Request a new review
* Process the comments from the review
* Move into mainline proper

42
drivers/staging/batman-adv/bat_sysfs.c
View File

@ -405,13 +405,17 @@ static ssize_t show_mesh_iface(struct kobject *kobj, struct attribute *attr,
struct device *dev = to_dev(kobj->parent);
struct net_device *net_dev = to_net_dev(dev);
struct batman_if *batman_if = get_batman_if_by_netdev(net_dev);
ssize_t length;
if (!batman_if)
return 0;
return sprintf(buff, "%s\n",
batman_if->if_status == IF_NOT_IN_USE ?
"none" : batman_if->soft_iface->name);
length = sprintf(buff, "%s\n", batman_if->if_status == IF_NOT_IN_USE ?
"none" : batman_if->soft_iface->name);
hardif_put(batman_if);
return length;
}
static ssize_t store_mesh_iface(struct kobject *kobj, struct attribute *attr,
@ -421,6 +425,7 @@ static ssize_t store_mesh_iface(struct kobject *kobj, struct attribute *attr,
struct net_device *net_dev = to_net_dev(dev);
struct batman_if *batman_if = get_batman_if_by_netdev(net_dev);
int status_tmp = -1;
int ret;
if (!batman_if)
return count;
@ -431,6 +436,7 @@ static ssize_t store_mesh_iface(struct kobject *kobj, struct attribute *attr,
if (strlen(buff) >= IFNAMSIZ) {
pr_err("Invalid parameter for 'mesh_iface' setting received: "
"interface name too long '%s'\n", buff);
hardif_put(batman_if);
return -EINVAL;
}
@ -440,13 +446,16 @@ static ssize_t store_mesh_iface(struct kobject *kobj, struct attribute *attr,
status_tmp = IF_I_WANT_YOU;
if ((batman_if->if_status == status_tmp) || ((batman_if->soft_iface) &&
(strncmp(batman_if->soft_iface->name, buff, IFNAMSIZ) == 0)))
(strncmp(batman_if->soft_iface->name, buff, IFNAMSIZ) == 0))) {
hardif_put(batman_if);
return count;
}
if (status_tmp == IF_NOT_IN_USE) {
rtnl_lock();
hardif_disable_interface(batman_if);
rtnl_unlock();
hardif_put(batman_if);
return count;
}
@ -457,7 +466,10 @@ static ssize_t store_mesh_iface(struct kobject *kobj, struct attribute *attr,
rtnl_unlock();
}
return hardif_enable_interface(batman_if, buff);
ret = hardif_enable_interface(batman_if, buff);
hardif_put(batman_if);
return ret;
}
static ssize_t show_iface_status(struct kobject *kobj, struct attribute *attr,
@ -466,23 +478,33 @@ static ssize_t show_iface_status(struct kobject *kobj, struct attribute *attr,
struct device *dev = to_dev(kobj->parent);
struct net_device *net_dev = to_net_dev(dev);
struct batman_if *batman_if = get_batman_if_by_netdev(net_dev);
ssize_t length;
if (!batman_if)
return 0;
switch (batman_if->if_status) {
case IF_TO_BE_REMOVED:
return sprintf(buff, "disabling\n");
length = sprintf(buff, "disabling\n");
break;
case IF_INACTIVE:
return sprintf(buff, "inactive\n");
length = sprintf(buff, "inactive\n");
break;
case IF_ACTIVE:
return sprintf(buff, "active\n");
length = sprintf(buff, "active\n");
break;
case IF_TO_BE_ACTIVATED:
return sprintf(buff, "enabling\n");
length = sprintf(buff, "enabling\n");
break;
case IF_NOT_IN_USE:
default:
return sprintf(buff, "not in use\n");
length = sprintf(buff, "not in use\n");
break;
}
hardif_put(batman_if);
return length;
}
static BAT_ATTR(mesh_iface, S_IRUGO | S_IWUSR,

29
drivers/staging/batman-adv/hard-interface.c
View File

@ -49,6 +49,9 @@ struct batman_if *get_batman_if_by_netdev(struct net_device *net_dev)
batman_if = NULL;
out:
if (batman_if)
hardif_hold(batman_if);
rcu_read_unlock();
return batman_if;
}
@ -96,6 +99,9 @@ static struct batman_if *get_active_batman_if(struct net_device *soft_iface)
batman_if = NULL;
out:
if (batman_if)
hardif_hold(batman_if);
rcu_read_unlock();
return batman_if;
}
@ -292,6 +298,7 @@ int hardif_enable_interface(struct batman_if *batman_if, char *iface_name)
batman_if->batman_adv_ptype.type = __constant_htons(ETH_P_BATMAN);
batman_if->batman_adv_ptype.func = batman_skb_recv;
batman_if->batman_adv_ptype.dev = batman_if->net_dev;
hardif_hold(batman_if);
dev_add_pack(&batman_if->batman_adv_ptype);
atomic_set(&batman_if->seqno, 1);
@ -350,13 +357,20 @@ void hardif_disable_interface(struct batman_if *batman_if)
bat_info(batman_if->soft_iface, "Removing interface: %s\n",
batman_if->net_dev->name);
dev_remove_pack(&batman_if->batman_adv_ptype);
hardif_put(batman_if);
bat_priv->num_ifaces--;
orig_hash_del_if(batman_if, bat_priv->num_ifaces);
if (batman_if == bat_priv->primary_if)
set_primary_if(bat_priv,
get_active_batman_if(batman_if->soft_iface));
if (batman_if == bat_priv->primary_if) {
struct batman_if *new_if;
new_if = get_active_batman_if(batman_if->soft_iface);
set_primary_if(bat_priv, new_if);
if (new_if)
hardif_put(new_if);
}
kfree(batman_if->packet_buff);
batman_if->packet_buff = NULL;
@ -410,6 +424,8 @@ static struct batman_if *hardif_add_interface(struct net_device *net_dev)
list_add_tail_rcu(&batman_if->list, &if_list);
spin_unlock(&if_list_lock);
/* extra reference for return */
hardif_hold(batman_if);
return batman_if;
free_if:
@ -459,7 +475,7 @@ static int hard_if_event(struct notifier_block *this,
struct bat_priv *bat_priv;
if (!batman_if && event == NETDEV_REGISTER)
batman_if = hardif_add_interface(net_dev);
batman_if = hardif_add_interface(net_dev);
if (!batman_if)
goto out;
@ -482,8 +498,10 @@ static int hard_if_event(struct notifier_block *this,
update_min_mtu(batman_if->soft_iface);
break;
case NETDEV_CHANGEADDR:
if (batman_if->if_status == IF_NOT_IN_USE)
if (batman_if->if_status == IF_NOT_IN_USE) {
hardif_put(batman_if);
goto out;
}
check_known_mac_addr(batman_if->net_dev->dev_addr);
update_mac_addresses(batman_if);
@ -495,6 +513,7 @@ static int hard_if_event(struct notifier_block *this,
default:
break;
};
hardif_put(batman_if);
out:
return NOTIFY_DONE;