Re: [ldv-project] [net] libertas: potential race condition
From: Pavel Andrianov <hidden>
Date: 2016-06-07 15:58:23
Also in:
linux-wireless, lkml
07.06.2016 18:39, Dan Williams пишет:
On Tue, 2016-06-07 at 13:30 +0400, Pavel Andrianov wrote:quoted
Hi! There is a potential race condition in drivers/net/wireless/libertas/libertas.ko. In the function lbs_hard_start_xmit(..), line 159, a socket buffer is written to priv->current_skb with a spin_lock protection. In the function lbs_mac_event_disconnected(..), lines 50-51, the field current_skb is cleaned. There is no protection used. The corresponding handlers are activated at the same time in lbs_start_card(..) and then may be executed simultaneously. Note, there are two structures lbs_netdev_ops and mesh_netdev_ops, which have the target handler lbs_hard_start_xmit. 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? Dan
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. -- Pavel Andrianov Linux Verification Center, ISPRAS web: http://linuxtesting.org e-mail: andrianov-ufN2psIa012HXe+LvDLADg@public.gmane.org -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html