netdev - Re: [PATCH] netfilter: xtables: fix reentrancy

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: <Pine.LNX.4.64.1103171231220.21558@ask.diku.dk>
Date:	Thu, 17 Mar 2011 12:36:56 +0100 (CET)
From:	Jesper Dangaard Brouer <hawk@...u.dk>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>,
	Patrick McHardy <kaber@...sh.net>,
	Netfilter Developers <netfilter-devel@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] netfilter: xtables: fix reentrancy


Hi Eric,

How critial is this bug fix?

Should I apply this on my stable production kernels?
(I'm preparing a 2.6.38 kernel for prod usage, eventhougt its just been 
released, because I want your SFQ fixes...)


On Thu, 17 Mar 2011, Eric Dumazet wrote:

> While looking at it (and trying to only require preemption disabled
> instead of BH disabled), I believe stackptr management is not safe.
>
> I suggest following patch to make sure we restore *stackptr to origptr
> before enabling BH (or preemption later)
>
> Thanks
>
> [PATCH] netfilter: xtables: fix reentrancy
>
> commit f3c5c1bfd4308 (make ip_tables reentrant) introduced a race in
> handling the stackptr restore, at the end of ipt_do_table()
>
> We should do it before the call to xt_info_rdunlock_bh(), or we allow
> cpu preemption and another cpu overwrites stackptr of original one.
>
> A second fix is to change the underflow test to check the origptr value
> instead of 0 to detect underflow, or else we allow a jump from different
> hooks.
>
> Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
[...]

Hilsen
   Jesper Brouer

--
-------------------------------------------------------------------
MSc. Master of Computer Science
Dept. of Computer Science, University of Copenhagen
Author of http://www.adsl-optimizer.dk
-------------------------------------------------------------------
--
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