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Subject: Re: [PATCH] time: Validate the usec before covert to nsec in
 do_adjtimex
To:     Thomas Gleixner <tglx@linutronix.de>
CC:     <john.stultz@linaro.org>, <sboyd@kernel.org>,
        <linux-kernel@vger.kernel.org>
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From:   "zhangxiaoxu (A)" <zhangxiaoxu5@huawei.com>
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Date:   Mon, 8 Jul 2019 18:42:13 +0800
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?? 2019/7/8 17:24, Thomas Gleixner д??:
> On Mon, 8 Jul 2019, 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.
> 
> That's correct, but the actuall inject function wants to keep the sanity
> check,
timekeeping_inject_offset is called only by timekeeping_warp_clock and do_adjtimex.
The do_adjtimex already validate it, and timekeeping_warp_clock is set tv_nsec=0.
We keep the sanity check is for some other maybe use this function?
I had send a v2 to keep the sanity check in timekeeping_inject_offset.

Thanks.
> 
> Thanks,
> 
> 	tglx
> 
> .
>