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Message-ID: <4728A7D4.8050008@garzik.org>
Date: Wed, 31 Oct 2007 12:05:40 -0400
From: Jeff Garzik <jeff@...zik.org>
To: Jens Axboe <jens.axboe@...cle.com>
CC: Alan Cox <alan@...rguk.ukuu.org.uk>, Daniel Drake <dsd@...too.org>,
linux list <linux-kernel@...r.kernel.org>,
linux-ide@...r.kernel.org
Subject: Re: "Fix ATAPI transfer lengths" causes CD writing regression
Jens Axboe wrote:
> Right, that's of course problematic... There has to be a way to recover
> that situation though, or you can't export any user command issue
> facility.
You cannot hope to handle all possible effects arising from an app
providing an invalid sg header / cdb.
Once you start talking "recovery" you are already screwed: we are
talking about low-level hardware commands that are passed straight to
the hardware. It is trivial to lock up hardware, brick hardware, and
corrupt data at that level.
If this is NOT a privileged app, we must update the command validation
to ensure that invalid commands are not transported to the hardware.
If this is a privileged app, our work is done. Fix the app. We gave
root rope, and he took it.
I even venture to say that "accept anything, clean up afterwards" is
/impossible/ to implement, in addition to being dangerous.
Jeff
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