diff options
| author | Miroslav Lichvar <mlichvar@redhat.com> | 2019-06-18 17:47:13 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-06-22 11:28:53 +0200 |
| commit | d897a4ab11dc8a9fda50d2eccc081a96a6385998 (patch) | |
| tree | fade4e9ee1de5f30818462dc1f36e3d75dfd6e9b /kernel/time/ntp.c | |
| parent | 141e1ecda356bb0034027a9acb949e97a963ba16 (diff) | |
ntp: Limit TAI-UTC offset
Don't allow the TAI-UTC offset of the system clock to be set by adjtimex()
to a value larger than 100000 seconds.
This prevents an overflow in the conversion to int, prevents the CLOCK_TAI
clock from getting too far ahead of the CLOCK_REALTIME clock, and it is
still large enough to allow leap seconds to be inserted at the maximum rate
currently supported by the kernel (once per day) for the next ~270 years,
however unlikely it is that someone can survive a catastrophic event which
slowed down the rotation of the Earth so much.
Reported-by: Weikang shi <swkhack@gmail.com>
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Link: https://lkml.kernel.org/r/20190618154713.20929-1-mlichvar@redhat.com
Diffstat (limited to 'kernel/time/ntp.c')
| -rw-r--r-- | kernel/time/ntp.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index 8de4f789dc1b..65eb796610dc 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -43,6 +43,7 @@ static u64 tick_length_base; #define MAX_TICKADJ 500LL /* usecs */ #define MAX_TICKADJ_SCALED \ (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ) +#define MAX_TAI_OFFSET 100000 /* * phase-lock loop variables @@ -691,7 +692,8 @@ static inline void process_adjtimex_modes(const struct __kernel_timex *txc, time_constant = max(time_constant, 0l); } - if (txc->modes & ADJ_TAI && txc->constant >= 0) + if (txc->modes & ADJ_TAI && + txc->constant >= 0 && txc->constant <= MAX_TAI_OFFSET) *time_tai = txc->constant; if (txc->modes & ADJ_OFFSET) |