linux-kernel - Re: [PATCH] net: fix race in the receive/select

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: <87eit3l7y6.fsf@basil.nowhere.org>
Date:	Mon, 29 Jun 2009 11:12:33 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	fbl@...hat.com, nhorman@...hat.com, davem@...hat.com,
	oleg@...hat.com, eric.dumazet@...il.com
Subject: Re: [PATCH] net: fix race in the receive/select

Jiri Olsa <jolsa@...hat.com> writes:

> Adding memory barrier to the __pollwait function paired with 
> receive callbacks.  The smp_mb__after_lock define is added, 
> since {read|write|spin}_lock() on x86 are full memory barriers.

I was wondering did you see that race actually happening in practice?
If yes on which system?

At least on x86 I can't see how it happens. mb() is only a compile
time barrier and the compiler doesn't optimize over indirect callbacks
like __pollwait() anyways.

It might be still needed on some weaker ordered architectures, but did you
actually see it there?

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/