linux-kernel - Re: Process-shared futexes on hugepages puts the kernel in an infinite loop in 2.6.32.11; is this fixed now?

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: <20100419161102.GZ32034@random.random>
Date:	Mon, 19 Apr 2010 18:11:02 +0200
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Mel Gorman <mel@....ul.ie>, r6144 <rainy6144@...il.com>,
	linux-kernel@...r.kernel.org, Darren Hart <dvhltc@...ibm.com>,
	tglx <tglx@...utronix.de>,
	Lee Schermerhorn <lee.schermerhorn@...com>
Subject: Re: Process-shared futexes on hugepages puts the kernel in an
 infinite loop in 2.6.32.11; is this fixed now?

On Mon, Apr 19, 2010 at 05:45:05PM +0200, Peter Zijlstra wrote:
> Wouldn't a longer poison be more recognisable? Also, shouldn't this use
> POISON_POINTER_DELTA?
> 
> Something like:
> 
> #define HUGETBL_POISON	((void *) 0x00300300 + POISON_POINTER_DELTA)
> 
> 0x2e5 isn't that high, I've had actual derefs in that range.

The default at kernel config time sets only 4k as unmapped (I think
it's a very bad default for 64bit archs), so above 4k userland can map
it and you can have actual derefs with 0x00300300 but not with Mel's
preferred <0x1000 address. So the address must be <0x1000.
--
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/