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    SubjectRe: /dev/urandom uses uninit bytes, leaks user data
    On Sat, Dec 15, 2007 at 03:13:19PM +0800, Herbert Xu wrote:
    > John Reiser <jreiser@bitwagon.com> wrote:
    > >
    > > If speed matters that much, then please recoup 33 cycles on x86
    > > by using shifts instead of three divides, such as (gcc 4.1.2):
    > >
    > > add_entropy_words(r, tmp, (bytes + 3) / 4);
    > >
    > > 0x8140689 <xfer_secondary_pool+206>: lea 0x3(%esi),%eax
    > > 0x814068c <xfer_secondary_pool+209>: mov $0x4,%dl
    > > 0x814068e <xfer_secondary_pool+211>: mov %edx,%edi
    > > 0x8140690 <xfer_secondary_pool+213>: cltd
    > > 0x8140691 <xfer_secondary_pool+214>: idiv %edi
    >
    > There ought to be a warning about this sort of thing.

    Indeed. Seems it would be better to adjust the types appropriately.
    Anyway, this is no longer relevant to security@.

    --
    Mathematics is the supreme nostalgia of our time.


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