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    SubjectRe: [CRYPTO]: Miscompiling sha256.c by gcc 3.2.3 and arch pentium3,4
    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@vger.kernel.org
    >[mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of James Morris
    >Sent: Friday, January 30, 2004 9:40 AM
    >To: R CHAN
    >Cc: linux-kernel@vger.kernel.org; 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@redhat.com>
    >
    >
    >-
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    >

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