[patches] a bunch of old bluetooth fixes

[Al Viro <viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>]

	This stuff has been sitting in my queue since March; basically,
several places in net/bluetooth assume that they are dealing with
l2cap sockets, while it is possible to get an arbitrary socket to those.
Results are not pretty.
	* HIDPCONNADD gets an arbitrary user-supplied socket; the code
it calls (hidp_connection_add()) verifies that the socket is l2cap one,
but before doing so it finds l2cap_pi(ctrl_sock->sk)->chan.  It's not
that big a deal (it's only 5 words past the end of struct sock), but
it's trivial to avoid and, in theory, we might end up oopsing here if
we are very unlucky and it happens to hit an unmapped page just past
the actual object ctrl_sock->sk sits in.
	* CMTP counterpart of that doesn't validate the socket at all.
It proceeds to
        s = __cmtp_get_session(&l2cap_pi(sock->sk)->chan->dst);
which can very easily oops - here ->chan is already garbage and we
proceed to dereference that.  As with HIDP, one needs CAP_NET_ADMIN to
trigger that, but it's really a clear bug.  The only sanity check we
do is verifying that nsock->sk->sk_state is equal to BT_CONNECTED,
which is not unique to bluetooth, to put it mildly.  It's just 1,
so a TCP_ESTABLISHED tcp socket will pass that check just fune.
The fix is trivial...
	* BNEP situation is identical to CMTP one.

I've sent these patches back then (March 10), but they seem to have fallen
through the cracks.  The bugs are still there and the fixes still apply.
If you would prefer me to resend them after -rc1, just tell...

Anyway, patches follow