On Mon, Jul 08, 2019 at 03:55:04PM +0800, ZhangXiaoxu wrote:
> When covert the usec to nsec, it will multiple 1000, it maybe
> overflow and lead an undefined behavior.
>
> For example, users may input an negative tv_usec values when
> call adjtimex syscall, then multiple 1000 maybe overflow it
> to a positive and legal number.
>
> So, we should validate the usec before coverted it to nsec.
>
> Signed-off-by: ZhangXiaoxu <zhangxiao...@huawei.com>
> ---
> kernel/time/timekeeping.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
> index 44b726b..e5c1d00 100644
> --- a/kernel/time/timekeeping.c
> +++ b/kernel/time/timekeeping.c
> @@ -1272,9 +1272,6 @@ static int timekeeping_inject_offset(const struct
> timespec64 *ts)
> struct timespec64 tmp;
> int ret = 0;
>
> - if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
> - return -EINVAL;
> -
> raw_spin_lock_irqsave(&timekeeper_lock, flags);
> write_seqcount_begin(&tk_core.seq);
>
> @@ -2321,6 +2318,9 @@ int do_adjtimex(struct __kernel_timex *txc)
>
> if (txc->modes & ADJ_SETOFFSET) {
> struct timespec64 delta;
> +
> + if (txc->time.tv_usec < 0 || txc->time.tv_usec >= USEC_PER_SEC)
> + return -EINVAL;
This test is wrong. If the tv_usec field is in nanoseconds, then the
value can easily be greater than USEC_PER_SEC.
> delta.tv_sec = txc->time.tv_sec;
> delta.tv_nsec = txc->time.tv_usec;
> if (!(txc->modes & ADJ_NANO))
> --
> 2.7.4
>
Thanks,
Richard
