linux-kernel - Re: [PATCH 2/2] x86_64 irq: Handle irqs pending in IRR during irq migration.

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]

Date:	Fri, 02 Feb 2007 18:39:15 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Andrew Morton <akpm@...l.org>
Cc:	<linux-kernel@...r.kernel.org>, "Lu, Yinghai" <yinghai.lu@....com>,
	"Luigi Genoni" <luigi.genoni@...elli.com>,
	Ingo Molnar <mingo@...e.hu>,
	Natalie Protasevich <protasnb@...il.com>,
	Andi Kleen <ak@...e.de>
Subject: Re: [PATCH 2/2] x86_64 irq:  Handle irqs pending in IRR during irq migration.

Andrew Morton <akpm@...l.org> writes:

> So is this a for-2.6.20 thing?  The bug was present in 2.6.19, so
> I assume it doesn't affect many people?

If it's not to late, and this patch isn't too scary.

It's a really rare set of circumstances that trigger it, but the
possibility of being hit is pretty widespread, anything with
more than one cpu, and more then one irq could see this.

The easiest way to trigger this is to have two level triggered irqs on
two different cpus using the same vector.  In that case if one acks
it's irq while the other irq is migrating to a different cpu 2.6.19
get completely confused and stop handling interrupts properly.

With my previous bug fix (not to drop the ack when we are confused)
the machine will stay up, and that is obviously correct and can't
affect anything else so is probably a candidate for the stable tree.

With this fix everything just works.

I don't know how often a legitimate case of the exact same irq
going off twice in a row is, but that is a possibility as well
especially with edge triggered interrupts.

Setting up the test scenario was a pain, but by extremely limiting
my choice of vectors I was able to confirm I survived several hundred
of these events with in a couple of minutes no problem.

Eric
-
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/