Re: [PATCH 1/4] l2cap endianness annotations

From: Al Viro
Date: Sun Oct 15 2006 - 19:49:38 EST


On Mon, Oct 16, 2006 at 01:39:03AM +0200, Marcel Holtmann wrote:
> this data structure is visible to the userspace (via the Bluetooth
> library headers). Do we annotate them, too?

Yes. linux/types.h is exported header and it defines all endian types.

> > @@ -221,7 +221,7 @@ struct l2cap_pinfo {
> >
> > __u8 ident;
> >
> > - __u16 sport;
> > + __le16 sport;
> >
> > struct l2cap_conn *conn;
> > struct sock *next_c;
>
> These are internal. We should have to annotate them. They should store
> it in host order. If not, than that is the problem.

They do not. Trivial search in vanilla tree shows
for (psm = 0x1001; psm < 0x1100; psm += 2)
if (!__l2cap_get_sock_by_addr(psm, src)) {
l2cap_pi(sk)->psm = htobs(psm);
l2cap_pi(sk)->sport = htobs(psm);
err = 0;
break;
}

which is very definitely not putting a host-endian there. You can
switch it to host-endian, of course, but then you have to modify
at least that place.

> > @@ -1533,7 +1533,7 @@ static inline int l2cap_config_req(struc
> > if (!(sk = l2cap_get_chan_by_scid(&conn->chan_list, dcid)))
> > return -ENOENT;
> >
> > - l2cap_parse_conf_req(sk, req->data, cmd->len - sizeof(*req));
> > + l2cap_parse_conf_req(sk, req->data, __le16_to_cpu(cmd->len) - sizeof(*req));
>
> I have to look into this change. It basically means that this code never
> worked on big endian systems, but it actually does.

You are misreading it. Old code flipped cmd->len in place in the caller.
New one doesn't.
-
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