Hi,
I found that bt_proto manipulated in bt_sock_register is not guarded
from race condition.
Look at net/bluetooth/af_bluetooth.c:
static struct net_proto_family *bt_proto[BT_MAX_PROTO];
int bt_sock_register(int proto, struct net_proto_family *ops)
{
if (proto < 0 || proto >= BT_MAX_PROTO)
return -EINVAL;
if (bt_proto[proto])
return -EEXIST;
bt_proto[proto] = ops;
return 0;
}
Here bt_proto[proto] is set.
In other hand,
static int bt_sock_create(struct socket *sock, int proto)
{
int err = 0;
if (proto < 0 || proto >= BT_MAX_PROTO)
return -EINVAL;
#if defined(CONFIG_KMOD)
if (!bt_proto[proto]) {
request_module("bt-proto-%d", proto);
}
#endif
err = -EPROTONOSUPPORT;
if (bt_proto[proto] && try_module_get(bt_proto[proto]->owner)) {
err = bt_proto[proto]->create(sock, proto);
module_put(bt_proto[proto]->owner);
}
return err;
}
bt_proto[proto] is referred.
So I wrote a patch which guards bt_proto with rwlock.
Signed-off-by: Masatake YAMATO <[email protected]>
diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
index 469eda0..dff4514 100644
--- a/net/bluetooth/af_bluetooth.c
+++ b/net/bluetooth/af_bluetooth.c
@@ -27,6 +27,7 @@
#include <linux/config.h>
#include <linux/module.h>
+#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/errno.h>
@@ -54,30 +55,44 @@
/* Bluetooth sockets */
#define BT_MAX_PROTO 8
static struct net_proto_family *bt_proto[BT_MAX_PROTO];
+static DEFINE_RWLOCK(bt_proto_rwlock);
int bt_sock_register(int proto, struct net_proto_family *ops)
{
+ int err;
+
if (proto < 0 || proto >= BT_MAX_PROTO)
return -EINVAL;
- if (bt_proto[proto])
- return -EEXIST;
-
- bt_proto[proto] = ops;
- return 0;
+ err = -EEXIST;
+
+ write_lock(&bt_proto_rwlock);
+ if (bt_proto[proto] == NULL) {
+ err = 0;
+ bt_proto[proto] = ops;
+ }
+ write_unlock(&bt_proto_rwlock);
+
+ return err;
}
EXPORT_SYMBOL(bt_sock_register);
int bt_sock_unregister(int proto)
{
+ int err;
+
if (proto < 0 || proto >= BT_MAX_PROTO)
return -EINVAL;
-
- if (!bt_proto[proto])
- return -ENOENT;
-
- bt_proto[proto] = NULL;
- return 0;
+
+ err = -ENOENT;
+ write_lock(&bt_proto_rwlock);
+ if (bt_proto[proto]) {
+ err = 0;
+ bt_proto[proto] = NULL;
+ }
+ write_unlock(&bt_proto_rwlock);
+
+ return err;
}
EXPORT_SYMBOL(bt_sock_unregister);
@@ -94,10 +109,12 @@ static int bt_sock_create(struct socket
}
#endif
err = -EPROTONOSUPPORT;
+ read_lock(&bt_proto_rwlock);
if (bt_proto[proto] && try_module_get(bt_proto[proto]->owner)) {
err = bt_proto[proto]->create(sock, proto);
module_put(bt_proto[proto]->owner);
}
+ read_unlock(&bt_proto_rwlock);
return err;
}
-
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