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
