From: Ondrej Mosnacek <omosnace@redhat.com>
To: Roman Zippel <zippel@linux-m68k.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
John Stultz <john.stultz@linaro.org>,
Stephen Boyd <sboyd@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: kernel/time/ntp.c: Possible off-by-one error in TAI range check?
Date: Mon, 15 Apr 2019 10:02:54 +0200 [thread overview]
Message-ID: <CAFqZXNuqWGNwUTUxWjZRmx4PFL2zsRRo6fu+ZXZwaQAMvuf1kQ@mail.gmail.com> (raw)
In-Reply-To: <CAFqZXNsO63bX37T=bg=QRt6_EtpvXUNQ_N-TSXsN4=wd1Dz2zQ@mail.gmail.com>
On Mon, Apr 8, 2019 at 10:47 AM Ondrej Mosnacek <omosnace@redhat.com> wrote:
> Hello,
>
> while writing tests for clock adjustment auditing [1] [2], I stumbled
> upon a strange behavior of adjtimex(2) when setting the TAI offset...
>
> Commit 153b5d054ac2 ("ntp: support for TAI") added a possibility to
> change the TAI offset from userspace via adjtimex(2). The code checks
> if the input value (txc->constant) is greater than 0 and if it is not,
> then it doesn't modify the value. Ignoring the fact that this check
> should probably be in timekeeping_validate_timex() and cause -EINVAL
> to be returned when false, I find it strange that the check doesn't
> allow to set the value to 0, which seems to be the default value...
>
> Was this behavior intended or should the code actually check for
> txc->constant >= 0 instead of txc->constant > 0?
Ping?
>
> Thanks,
>
> [1] https://github.com/linux-audit/audit-kernel/issues/10
> [2] https://github.com/linux-audit/audit-kernel/wiki/RFE-More-detailed-auditing-of-changes-to-system-clock
>
> --
> Ondrej Mosnacek <omosnace at redhat dot com>
> Software Engineer, Security Technologies
> Red Hat, Inc.
--
Ondrej Mosnacek <omosnace at redhat dot com>
Software Engineer, Security Technologies
Red Hat, Inc.
next prev parent reply other threads:[~2019-04-15 8:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-08 8:47 kernel/time/ntp.c: Possible off-by-one error in TAI range check? Ondrej Mosnacek
2019-04-15 8:02 ` Ondrej Mosnacek [this message]
2019-04-15 8:09 ` Thomas Gleixner
2019-04-15 8:56 ` Miroslav Lichvar
2019-04-16 19:59 ` Thomas Gleixner
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