在 2021/4/12 23:58, Richard Cochran 写道:
> On Mon, Apr 12, 2021 at 02:52:11PM +0000, chenjun (AM) wrote:
>> 在 2021/4/12 22:20, Richard Cochran 写道:
>>> On Mon, Apr 12, 2021 at 12:45:51PM +0000, Chen Jun wrote:
>>>> the correct error is covered by put_old_timex32.
>>>
>>> Well, the non-negative return code (TIME_OK, TIME_INS, etc) is
>>> clobbered by put_old_timex32().
>>>
>>>> Fixes: f1f1d5ebd10f ("posix-timers: Introduce a syscall for clock tuning.")
>>>
>>> This is not the correct commit for the "Fixes" tag. Please find the
>>> actual commit that introduced the issue.
>>>
>>> In commit f1f1d5ebd10f the code looked like this...
>>>
>>> long compat_sys_clock_adjtime(clockid_t which_clock,
>>> struct compat_timex __user *utp)
>>> {
>>> struct timex txc;
>>> mm_segment_t oldfs;
>>> int err, ret;
>>>
>>> err = compat_get_timex(&txc, utp);
>>> if (err)
>>> return err;
>>>
>>> oldfs = get_fs();
>>> set_fs(KERNEL_DS);
>>> ret = sys_clock_adjtime(which_clock, (struct timex __user *)
>>> &txc);
>>> set_fs(oldfs);
>>>
>>> err = compat_put_timex(utp, &txc);
>>> if (err)
>>> return err;
>>>
>>> return ret;
>>> }
>
> Look at the code ^^^
>
>> The implement of clock_adjtime32 is similar to compat_sys_clock_adjtime.
>> And I think f1f1d5ebd10 introduced the problem actually.
>
> See how 'ret' and 'err' are two separate variables? It makes a difference.
>
> Thanks,
> Richard
>
Oh, yee.. Very thanks.
3a4d44b616 ("ntp: Move adjtimex related compat syscalls to native
counterparts") made the change.
--
Regards
Chen Jun
