[ldv-project] [net] libertas: potential race condition
andrianov at ispras.ru
Tue Jun 7 07:54:23 PDT 2016
07.06.2016 18:39, Dan Williams пишет:
> On Tue, 2016-06-07 at 13:30 +0400, Pavel Andrianov wrote:
>> There is a potential race condition in
>> In the function lbs_hard_start_xmit(..), line 159, a socket buffer
>> written to priv->current_skb with a spin_lock protection.
>> In the function lbs_mac_event_disconnected(..), lines 50-51, the
>> current_skb is cleaned. There is no protection used. The
>> handlers are activated at the same time in lbs_start_card(..) and
>> may be executed simultaneously. Note, there are two structures
>> lbs_netdev_ops and mesh_netdev_ops, which have the target handler
>> Is it a real race or I have missed something?
> Yeah, it looks like it should be grabbing priv->driver_lock before
> clearing priv->currenttxskb in lbs_mac_event_disconnected(). Care to
> submit a patch after testing? Do you have any of that hardware?
I have no that hardware and I have some doubts about the simple fix,
you've suggested. For instance, in lbs_hard_start_xmit the lock is
acquired twice and the priv->tx_pending_len can be modified also by
lbs_mac_event_disconnected (even if spin_lock will be added to
lbs_mac_event_disconnected). Moreover, the function lbs_send_tx_feedback
also cleaned priv->currenttxskb, but it happens also without any
protection. Thus, the fix has to be more complicated, and I have no
ideas about it.
Linux Verification Center, ISPRAS
e-mail: andrianov at ispras.ru
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