@@ -228,6 +228,7 @@ typedef struct ax25_dev {
ax25_dama_info dama;
#endif
refcount_t refcount;
+ bool device_up;
} ax25_dev;
typedef struct ax25_cb {
@@ -62,12 +62,12 @@ static void ax25_free_sock(struct sock *sk)
*/
static void ax25_cb_del(ax25_cb *ax25)
{
+ spin_lock_bh(&ax25_list_lock);
if (!hlist_unhashed(&ax25->ax25_node)) {
- spin_lock_bh(&ax25_list_lock);
hlist_del_init(&ax25->ax25_node);
- spin_unlock_bh(&ax25_list_lock);
ax25_cb_put(ax25);
}
+ spin_unlock_bh(&ax25_list_lock);
}
/*
@@ -81,6 +81,7 @@ static void ax25_kill_by_device(struct net_device *dev)
if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
return;
+ ax25_dev->device_up = false;
spin_lock_bh(&ax25_list_lock);
again:
@@ -91,6 +92,7 @@ static void ax25_kill_by_device(struct net_device *dev)
spin_unlock_bh(&ax25_list_lock);
ax25_disconnect(s, ENETUNREACH);
s->ax25_dev = NULL;
+ ax25_cb_del(s);
spin_lock_bh(&ax25_list_lock);
goto again;
}
@@ -103,6 +105,7 @@ static void ax25_kill_by_device(struct net_device *dev)
dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker);
ax25_dev_put(ax25_dev);
}
+ ax25_cb_del(s);
release_sock(sk);
spin_lock_bh(&ax25_list_lock);
sock_put(sk);
@@ -1053,11 +1056,13 @@ static int ax25_release(struct socket *sock)
ax25_destroy_socket(ax25);
}
if (ax25_dev) {
- del_timer_sync(&ax25->timer);
- del_timer_sync(&ax25->t1timer);
- del_timer_sync(&ax25->t2timer);
- del_timer_sync(&ax25->t3timer);
- del_timer_sync(&ax25->idletimer);
+ if (!ax25_dev->device_up) {
+ del_timer_sync(&ax25->timer);
+ del_timer_sync(&ax25->t1timer);
+ del_timer_sync(&ax25->t2timer);
+ del_timer_sync(&ax25->t3timer);
+ del_timer_sync(&ax25->idletimer);
+ }
dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker);
ax25_dev_put(ax25_dev);
}
@@ -62,6 +62,7 @@ void ax25_dev_device_up(struct net_device *dev)
ax25_dev->dev = dev;
dev_hold_track(dev, &ax25_dev->dev_tracker, GFP_ATOMIC);
ax25_dev->forward = NULL;
+ ax25_dev->device_up = true;
ax25_dev->values[AX25_VALUES_IPDEFMODE] = AX25_DEF_IPDEFMODE;
ax25_dev->values[AX25_VALUES_AXDEFMODE] = AX25_DEF_AXDEFMODE;
The timers of ax25 are used for correct session cleanup. If we use ax25_release() to close ax25 sessions and ax25_dev is not null, the del_timer_sync() functions in ax25_release() will execute. As a result, the sessions could not be cleaned up correctly, because the timers have stopped. This patch adds a device_up flag in ax25_dev in order to judge whether the device is up. If there are sessions to be cleaned up, the del_timer_sync() in ax25_release() will not execute. What's more, we add ax25_cb_del() in ax25_kill_by_device(), because the timers have been stopped and there are no functions that could delete ax25_cb if we do not call ax25_release(). Finally, we reorder the position of ax25_list_lock in ax25_cb_del() in order to synchronize among different functions that call ax25_cb_del(). Fixes: 82e31755e55f ("ax25: Fix UAF bugs in ax25 timers") Reported-and-tested-by: Thomas Osterried <thomas@osterried.de> Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> --- Changes in v3: - Mitigate race conditions through lock. include/net/ax25.h | 1 + net/ax25/af_ax25.c | 19 ++++++++++++------- net/ax25/ax25_dev.c | 1 + 3 files changed, 14 insertions(+), 7 deletions(-)