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From: Rusty Russell <rusty@rustcorp.com.au>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: linux-kernel@vger.kernel.org, rusty@rustcorp.com.au,
        alan@lxorguk.ukuu.org.uk
Subject: Re: AUDIT: copy_from_user is a deathtrap. 
In-Reply-To: Your message of "Sat, 18 May 2002 09:14:10 MST."
             <Pine.LNX.4.44.0205180910570.26742-100000@home.transmeta.com> 
Date: Sun, 19 May 2002 12:10:38 +1000
Message-Id: <E179GA4-0004ZT-00@wagner.rustcorp.com.au>
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In message <Pine.LNX.4.44.0205180910570.26742-100000@home.transmeta.com> you wr
ite:
> 
> 
> On 18 May 2002, Andi Kleen wrote:
> >
> > Are you sure they even exist ?
> 
> Oh, like read() or write() for regular files? Yup, they exist.

Huh?  No, you ask for 2000 bytes into a buffer that can only take 1000
bytes without hitting an unmapped page, returning EFAULT or giving a
SIGSEGV is perfectly acceptable.

As a coder, I'd *really* prefer that to hiding the bug!

There's only one case which really actually cares for a valid reason:
the hack in copying mount options.

Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.