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    Subject[PATCH 3.13.y-ckt 065/103] time: adjtimex: Validate the ADJ_FREQUENCY values
    Date
    3.13.11-ckt16 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Sasha Levin <sasha.levin@oracle.com>

    commit 5e5aeb4367b450a28f447f6d5ab57d8f2ab16a5f upstream.

    Verify that the frequency value from userspace is valid and makes sense.

    Unverified values can cause overflows later on.

    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
    [jstultz: Fix up bug for negative values and drop redunent cap check]
    Signed-off-by: John Stultz <john.stultz@linaro.org>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    kernel/time/ntp.c | 7 +++++++
    1 file changed, 7 insertions(+)

    diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
    index af8d1d4..28db9be 100644
    --- a/kernel/time/ntp.c
    +++ b/kernel/time/ntp.c
    @@ -631,6 +631,13 @@ int ntp_validate_timex(struct timex *txc)
    if ((txc->modes & ADJ_SETOFFSET) && (!capable(CAP_SYS_TIME)))
    return -EPERM;

    + if (txc->modes & ADJ_FREQUENCY) {
    + if (LONG_MIN / PPM_SCALE > txc->freq)
    + return -EINVAL;
    + if (LONG_MAX / PPM_SCALE < txc->freq)
    + return -EINVAL;
    + }
    +
    return 0;
    }

    --
    1.9.1


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