Re: [PATCH] unix: avoid use-after-free in ep_remove_wait_queue

From: Hannes Frederic Sowa
Date: Wed Nov 11 2015 - 13:52:15 EST


On Wed, Nov 11, 2015, at 17:12, Rainer Weikusat wrote:
> Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx> writes:
> > On Tue, Nov 10, 2015, at 22:55, Rainer Weikusat wrote:
> >> An AF_UNIX datagram socket being the client in an n:1 association with
> >> some server socket is only allowed to send messages to the server if the
> >> receive queue of this socket contains at most sk_max_ack_backlog
> >> datagrams.
> [...]
> > This whole patch seems pretty complicated to me.
> >
> > Can't we just remove the unix_recvq_full checks alltogether and unify
> > unix_dgram_poll with unix_poll?
> >
> > If we want to be cautious we could simply make unix_max_dgram_qlen limit
> > the number of skbs which are in flight from a sending socket. The skb
> > destructor can then decrement this. This seems much simpler.
> >
> > Would this work?
> In the way this is intended to work, cf

Oh, I see, we don't limit closed but still referenced sockets. This
actually makes sense on how fd handling is implemented, just as a range

Have you checked if we can somehow deregister the socket in the poll
event framework? You wrote that it does not provide such a function but
maybe it would be easy to add?

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at