netdev - Re: Linux 2.6.35/TIPC 2.0 ABI breaking changes [was: TIPC 2.0 and TIPC_SUB

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20101018184628.GX8781@llucax.com.ar>
Date:	Mon, 18 Oct 2010 15:46:28 -0300
From:	Leandro Lucarella <luca@...cax.com.ar>
To:	Jon Maloy <jon.maloy@...csson.com>
Cc:	davem@...hat.com,
	"tipc-discussion@...ts.sourceforge.net" 
	<tipc-discussion@...ts.sourceforge.net>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: Linux 2.6.35/TIPC 2.0 ABI breaking changes [was: TIPC 2.0 and
 TIPC_SUB_SERVICE]

Leandro Lucarella, el 18 de octubre a las 12:04 me escribiste:
> This means D can't be used to write code that uses TIPC if you target
> kernels >= 2.6.35 (unless they write their own bindings, or at least use
> a custom TIPC_SUB_SERVICE constant). I could change the TIPC_SUB_SERVICE
> value, but then people using older kernels will be screwed. Another
> option is to use the version statement (kind of like C's #ifdef):
> 
> 	version (TIPC_2_0)
> 		const TIPC_SUB_SERVICE = 0x00;
> 	else
> 		const TIPC_SUB_SERVICE = 0x02;

I keep finding problems with this change. Another, no D-related, problem
with this change is old code could be silently (and very subtly) broken
if they check for TIPC_SUB_SERVICE as a flag with something like:

	if (s.filter & TIPC_SUB_SERVICE)
		/* do something */

Because TIPC_SUB_SERVICE has changed its semantics, not just its value,
and the new value (0x00) will give you always 0 in that test. This one
is really tricky, because the application code will fail silently, there
will be no dmesg indication of a failure, nor the connection to the
topology service be closed. You might get a compiler warning if you're
lucky.

-- 
Leandro Lucarella (AKA luca)                     http://llucax.com.ar/
----------------------------------------------------------------------
GPG Key: 5F5A8D05 (F8CD F9A7 BF00 5431 4145  104C 949E BFB6 5F5A 8D05)
----------------------------------------------------------------------
Novocaine for the soul
you better give me something
to fill the hole
before I sputter out
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html