mirror of
https://github.com/Fishwaldo/Star64_linux.git
synced 2025-03-17 20:54:10 +00:00
net: usb: lan78xx: reorder cleanup operations to avoid UAF bugs
The timer dev->stat_monitor can schedule the delayed work dev->wq and
the delayed work dev->wq can also arm the dev->stat_monitor timer.
When the device is detaching, the net_device will be deallocated. but
the net_device private data could still be dereferenced in delayed work
or timer handler. As a result, the UAF bugs will happen.
One racy situation is shown below:
(Thread 1) | (Thread 2)
lan78xx_stat_monitor() |
... | lan78xx_disconnect()
lan78xx_defer_kevent() | ...
... | cancel_delayed_work_sync(&dev->wq);
schedule_delayed_work() | ...
(wait some time) | free_netdev(net); //free net_device
lan78xx_delayedwork() |
//use net_device private data |
dev-> //use |
Although we use cancel_delayed_work_sync() to cancel the delayed work
in lan78xx_disconnect(), it could still be scheduled in timer handler
lan78xx_stat_monitor().
Another racy situation is shown below:
(Thread 1) | (Thread 2)
lan78xx_delayedwork |
mod_timer() | lan78xx_disconnect()
| cancel_delayed_work_sync()
(wait some time) | if (timer_pending(&dev->stat_monitor))
| del_timer_sync(&dev->stat_monitor);
lan78xx_stat_monitor() | ...
lan78xx_defer_kevent() | free_netdev(net); //free
//use net_device private data|
dev-> //use |
Although we use del_timer_sync() to delete the timer, the function
timer_pending() returns 0 when the timer is activated. As a result,
the del_timer_sync() will not be executed and the timer could be
re-armed.
In order to mitigate this bug, We use timer_shutdown_sync() to shutdown
the timer and then use cancel_delayed_work_sync() to cancel the delayed
work. As a result, the net_device could be deallocated safely.
What's more, the dev->flags is set to EVENT_DEV_DISCONNECT in
lan78xx_disconnect(). But it could still be set to EVENT_STAT_UPDATE
in lan78xx_stat_monitor(). So this patch put the set_bit() behind
timer_shutdown_sync().
Fixes: 77dfff5bb7
("lan78xx: Fix race condition in disconnect handling")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
8469c7f547
commit
1e7417c188
1 changed files with 2 additions and 5 deletions
|
@ -4224,8 +4224,6 @@ static void lan78xx_disconnect(struct usb_interface *intf)
|
|||
if (!dev)
|
||||
return;
|
||||
|
||||
set_bit(EVENT_DEV_DISCONNECT, &dev->flags);
|
||||
|
||||
netif_napi_del(&dev->napi);
|
||||
|
||||
udev = interface_to_usbdev(intf);
|
||||
|
@ -4233,6 +4231,8 @@ static void lan78xx_disconnect(struct usb_interface *intf)
|
|||
|
||||
unregister_netdev(net);
|
||||
|
||||
timer_shutdown_sync(&dev->stat_monitor);
|
||||
set_bit(EVENT_DEV_DISCONNECT, &dev->flags);
|
||||
cancel_delayed_work_sync(&dev->wq);
|
||||
|
||||
phydev = net->phydev;
|
||||
|
@ -4247,9 +4247,6 @@ static void lan78xx_disconnect(struct usb_interface *intf)
|
|||
|
||||
usb_scuttle_anchored_urbs(&dev->deferred);
|
||||
|
||||
if (timer_pending(&dev->stat_monitor))
|
||||
del_timer_sync(&dev->stat_monitor);
|
||||
|
||||
lan78xx_unbind(dev, intf);
|
||||
|
||||
lan78xx_free_tx_resources(dev);
|
||||
|
|
Loading…
Add table
Reference in a new issue