linux-kernel - Re: [PATCH] timerfd/eventfd context lock doesn't protect against poll

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 for Android: free password hash cracker in your pocket

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

Date:	Thu, 17 May 2007 23:37:22 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Davide Libenzi <davidel@...ilserver.org>
Cc:	Davi Arnaut <davi@...ent.com.br>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] timerfd/eventfd context lock doesn't protect against
 poll_wait

On Thu, 17 May 2007 23:20:05 -0700 (PDT) Davide Libenzi <davidel@...ilserver.org> wrote:

> On Fri, 18 May 2007, Davi Arnaut wrote:
> 
> > Hi,
> > 
> > poll_wait() callback may modify the waitqueue without holding the
> > context private lock.
> 
> Thx Davi, patch is correct. Nice catch. But at this point instead of 
> ending up getting two locks, we may look into using Andrew suggestion of 
> reusing the waitqueue lock. Is it universally considered a "legal" 
> operation?
> 

I think it's a reasonable thing to do in core kernel code.  It'd be more
worrisome if it was done way down in some rarely-visited device driver.

btw, the code at present doesn't explicitly take care of WQ_FLAG_EXCLUSIVE.
I guess as you want wake-all behaviour that's OK, but it might be worth a
mention somewhrre.

hm, fs/signalfd.c is "Copyright (C) 2003 Linus Torvalds".  He was before
his time, that lad.

-
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/