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

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Date:   Tue, 6 Jun 2017 14:07:49 +0800
From:   Xishi Qiu <qiuxishi@...wei.com>
To:     Thomas Gleixner <tglx@...utronix.de>
CC:     LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>, <fenghua.yu@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        John Stultz <john.stultz@...aro.org>
Subject: Re: [RFC] ubsan: signed integer overflow in setitimer()

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?

Thanks,
Xishi Qiu

> Thanks,
> 
> 	tglx
> 
> .
>