Re: [PATCH] time: verify time values in adjtimex ADJ_SETOFFSET to avoid overflow

Thomas Gleixner
2015-12-05T17:11:04Z

On Thu, 3 Dec 2015, Sasha Levin wrote:

> Make sure the tv_usec makes sense. We might multiply them later which can
> cause an overflow and undefined behavior.
>
> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> ---
> kernel/time/timekeeping.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
> index d563c19..aa3c1c2 100644
> --- a/kernel/time/timekeeping.c
> +++ b/kernel/time/timekeeping.c
> @@ -1987,6 +1987,10 @@ int do_adjtimex(struct timex *txc)
>
> if (txc->modes & ADJ_SETOFFSET) {
> struct timespec delta;
> +
> + if (txc->time.tv_usec >= USEC_PER_SEC || txc->time.tv_usec <= -USEC_PER_SEC)
> + return -EINVAL;

That's not a canonical timeval. timeval_valid() is what you want to
check it. Or has adjtimex some magic exception here?

Thanks,

tglx