Re: [RFC] ubsan: signed integer overflow in setitimer()

Thomas Gleixner
2017-06-06T07:43:48Z

On Tue, 6 Jun 2017, Xishi Qiu wrote:
> On 2017/6/4 23:06, Thomas Gleixner wrote:
> > On Thu, 1 Jun 2017, Xishi Qiu wrote:
> >
> > Cc'ed John Stultz
> >
> >> Hi, this is the test case, and then I got ubsan error
> >> (signed integer overflow) report, so the root cause is from
> >> user or kernel? Shall we change something in timeval_valid()?
> >>
> >>
> >> struct itimerval new_value;
> >> int ret;
> >>
> >> new_value.it_interval.tv_sec = 140673496649799L;
> >> new_value.it_interval.tv_usec = 6;
> >> new_value.it_value.tv_sec = 140673496649807L;
> >> new_value.it_value.tv_usec = 5;
> >>
> >> ret = setitimer(ITIMER_VIRTUAL, &new_value, NULL);
> >>
> >>
> >> [ 533.326588] ================================================================================
> >> [ 533.335346] UBSAN: Undefined behaviour in ./include/linux/time.h:239:27
> >> [ 533.342155] signed integer overflow:
> >> [ 533.345837] 140673496649807 * 1000000000 cannot be represented in type 'long int'
> >> [ 533.422181] set_cpu_itimer+0x49c/0x540
> >> [ 533.442127] do_setitimer+0xe1/0x540
> >
> > We need a similar clamping of the conversion as we have for
> > timespec/val_to_ktime(). I'll have a look in the next days unless John
> > beats me to it.
> >
>
> Hi Thomas, anything new?

Let me spell it out to you again. I wrote on Sunday late night:

"I'll have a look in the next days ...."

Do you really think I need a reminder after 24 hours?

Thanks,

tglx