[PATCH] fixes the type of 'index' in struct open_request

[Sridhar Samudrala <samudrala@xxxxxxxxxx>]

The 'index' field in struct open_request is declared as __u8.
This field is used to cache the syn table hash bucket index of a openreq and 
is set in tcp_v4_synq_add(). 

        unsigned h = tcp_v4_synq_hash(req->af.v4_req.rmt_addr, req->rmt_port);
        ....
        req->index = h;

The value that is set to this field can be any number between 0 and 
TCP_SYNQ_HASH_SIZE(512). The assignment causes an incorrect type conversion 
when the the openreq hashes to a value more than 255.

Looks like this field is only set, but not being read anywhere within TCP 
currently, probably the reason why it was not noticed till now.
I came across this while working on a patch where i would like to use the index
field to get the syntable hash bucket index of the openreq instead of 
recalculating the hash.

A simple patch to fix this is to change the type of index to __u16.

--- tcp.h.orig  Thu Sep  6 16:46:57 2001
+++ tcp.h       Thu Sep  6 16:47:32 2001
@@ -498,7 +498,7 @@
        __u16                   rmt_port;
        __u16                   mss;
        __u8                    retrans;
-       __u8                    index;
+       __u16                   index;
        __u16   snd_wscale : 4, 
                rcv_wscale : 4, 
                tstamp_ok : 1,


Thanks
Sridhar