linux-kernel - Re: [PATCH] [10/16] POISON: Use bitmask/action code for try_to

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: <alpine.DEB.1.10.0904071802290.12192@qirst.com>
Date:	Tue, 7 Apr 2009 18:04:39 -0400 (EDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Andi Kleen <andi@...stfloor.org>
cc:	Lee.Schermerhorn@...com, npiggin@...e.de,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org
Subject: Re: [PATCH] [10/16] POISON: Use bitmask/action code for try_to_unmap
 behaviour

On Tue, 7 Apr 2009, Andi Kleen wrote:

> > Ignoring MLOCK? This means we are violating POSIX which says that an
> > MLOCKed page cannot be unmapped from a process?
>
> I'm sure if you can find sufficiently vague language in the document
> to standards lawyer around that requirement @)
>
> The alternative would be to panic.


If you unmmap a MLOCKed page then you may get memory corruption because
f.e. the Infiniband layer is doing DMA to that page.

> > How does that work for the poisoning case? We substitute a fresh page?
>
> It depends on the state of the page. If it was a clean disk mapped
> page yes (it's just invalidated and can be reloaded). If it's a dirty anon
> page the process is normally killed first (with advisory mode on) or only
> killed when it hits the corrupted page. The process can also
> catch the signal if it choses so. The late killing works with
> a special entry similar to the migration case, but that results
> in a special SIGBUS.

I think a process needs to be killed if any MLOCKed page gets corrupted
because the OS cannot keep the POSIX guarantees.

--
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/