Re: [CRYPTO]: Miscompiling sha256.c by gcc 3.2.3 and arch pentium3,4

[R Chan]

I've narrowed the problem - it seems to be a specific optimisation bug with
gcc-3.2.3-24 that comes with RedHat 3ES. The problem is not kernel 
related (sorry!)
as the guts of the file exhibits the same problem when compiled in user 
space.
(All the non-sha256 test vectors in tcrypt.ko pass BTW.)

The older gcc32 that comes with Fedora Cora 1 and the gcc33 there get it 
right.

For the actual files please check bug #114610 in 
https://bugzilla.redhat.com.
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=114610
- the bug report includes sha256.c, tcrypt.c, and types.h necessary to 
demonstrate
the problem in user space.





Dave Paris wrote:

> Has this been demonstrated on *any* system/arch using GCC 3.2.3 (or other
> 3.2 series) or is it limited in scope to the description below?  Does it
> seem to do this with other implementations (other than sha256.c) or other
> kernels?  Just trying to get an idea if this is a complier optimization bug
> or something much more limited in scope.
>
> My personal lab is currently being unboxed and I won't be able to run my own
> tests for another week or so.  (apologies in advance)
>
> In any case, this is *extremely* serious from a number of angles.
>
> Kind Regards,
> -dsp
>
> -----Original Message-----
> From: linux-kernel-owner@xxxxxxxxxxxxxxx
> [mailto:linux-kernel-owner@xxxxxxxxxxxxxxx]On Behalf Of James Morris
> Sent: Friday, January 30, 2004 9:40 AM
> To: R CHAN
> Cc: linux-kernel@xxxxxxxxxxxxxxx; David S. Miller
> Subject: Re: [CRYPTO]: Miscompiling sha256.c by gcc 3.2.3 and arch
> pentium3,4
>
>
> On Fri, 30 Jan 2004, R CHAN wrote:
>
>  
>
> > 2.6.2-rc2 sha256.c is miscompiled with gcc 3.2.3.
> > (User space is RedHat 3ES.)
> >
> > Just an observation:
> >
> > gcc 3.2.3 is miscompiling sha256.c when using
> > -O2 -march=pentium3
> > or pentium4.
> >
> > gcc 3.3.x is ok, or the problem disappears
> > if I use arch=i686 or reduce the optimisation level to -O2.
> >
> > Sympthoms are all the sha256 test vectors fail.
> > If I extract the guts of the file to compile in user space
> > the same problem occurs.
> >    
>
> Have you noticed if this happens for any of the other crypto algorithms?
>
>
>
> - James
> --
> James Morris
> <jmorris@xxxxxxxxxx>
>
>
> -
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