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    SubjectRe: [PATCH 4.16 163/196] random: fix crng_ready() test
    On Sat, Apr 28, 2018 at 08:00:03AM +0200, Greg Kroah-Hartman wrote:
    > On Fri, Apr 27, 2018 at 11:34:43AM -0500, Dan Rue wrote:
    > > On Sun, Apr 22, 2018 at 03:53:03PM +0200, Greg Kroah-Hartman wrote:
    > > > 4.16-stable review patch. If anyone has any objections, please let me know.
    > > >
    > > > ------------------
    > > >
    > > > From: Theodore Ts'o <tytso@mit.edu>
    > > >
    > > > commit 43838a23a05fbd13e47d750d3dfd77001536dd33 upstream.
    > > >
    > > > The crng_init variable has three states:
    > > >
    > > > 0: The CRNG is not initialized at all
    > > > 1: The CRNG has a small amount of entropy, hopefully good enough for
    > > > early-boot, non-cryptographical use cases
    > > > 2: The CRNG is fully initialized and we are sure it is safe for
    > > > cryptographic use cases.
    > > >
    > > > The crng_ready() function should only return true once we are in the
    > > > last state. This addresses CVE-2018-1108.
    > > >
    > > > Reported-by: Jann Horn <jannh@google.com>
    > > > Fixes: e192be9d9a30 ("random: replace non-blocking pool...")
    > > > Cc: stable@kernel.org # 4.8+
    > > > Signed-off-by: Theodore Ts'o <tytso@mit.edu>
    > > > Reviewed-by: Jann Horn <jannh@google.com>
    > > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    > >
    > > This patch has caused a regression on 4.16 using kselftest lib/printf.sh
    > > - specifically, when it runs "/sbin/modprobe test_printf". This
    > > regression has been detected on arm64 dragonboard 410c (not seen on
    > > other arm64 or x86_64 devices).
    > >
    > > /sbin/modprobe test_printf
    > > [ 22.725551] test_printf: hashing plain 'p' has unexpected format
    > > [ 22.726031] test_printf: failed 1 out of 236 tests
    > > modprobe: ERROR: could not insert 'test_printf': Invalid argument
    > >
    > > This problem has not been seen on 4.9 or 4.14 under the same
    > > conditions.
    >
    > Does 4.17-rc2 also fail like this?

    No, but I did see it in v4.17-rc2-102-g3442097b765c, and it was fixed in
    the subsequent build:

    good: v4.17-rc2-64-g26ed24e429d8
    bad: v4.17-rc2-102-g3442097b765c
    good: v4.17-rc2-104-g69bfd470f462

    I haven't investigated deeper though, and I do not see any changes to
    random in those above revisions. This test passes on all the other
    mainline builds, including v4.17-rc2.

    >
    > You all are testing the -rc releases, right? :)

    We test every push to mainline and we test -next daily.

    >
    > I think the random changes that will be in 4.17-rc3 should fix this, and
    > if so, I'll suck them in here too. But testing that would be good to
    > see happen...

    Waiting is fine with me.

    Thanks,
    Dan

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