svn commit: r316393 - head/sys/compat/linux

[Chagin Dmitry]

On Mon, Apr 03, 2017 at 03:57:29AM +1000, Bruce Evans wrote:
> On Sun, 2 Apr 2017, Chagin Dmitry wrote:
> 
> > On Sun, Apr 02, 2017 at 04:36:51PM +0300, Konstantin Belousov wrote:
> >> On Sun, Apr 02, 2017 at 07:46:13AM +0000, Dmitry Chagin wrote:
> >>> Author: dchagin
> >>> Date: Sun Apr  2 07:46:13 2017
> >>> New Revision: 316393
> >>> URL: https://svnweb.freebsd.org/changeset/base/316393
> >>>
> >>> Log:
> >>>   As noted by bde@ negative tv_sec values are not checked for overflow,
> >>>   so overflow can still occur. Fix that. Also remove the extra check for
> >>>   tv_sec size as under COMPAT_LINUX32 it is always true.
> >>>
> >>>   Pointed out by:	bde@
> >>>
> >>>   MFC after:	1 week
> >>>
> >>> Modified:
> >>>   head/sys/compat/linux/linux_time.c
> >>>
> >>> Modified: head/sys/compat/linux/linux_time.c
> >>> ==============================================================================
> >>> --- head/sys/compat/linux/linux_time.c	Sun Apr  2 07:11:15 2017	(r316392)
> >>> +++ head/sys/compat/linux/linux_time.c	Sun Apr  2 07:46:13 2017	(r316393)
> >>> @@ -125,8 +125,7 @@ native_to_linux_timespec(struct l_timesp
> >>>
> >>>  	LIN_SDT_PROBE2(time, native_to_linux_timespec, entry, ltp, ntp);
> >>>  #ifdef COMPAT_LINUX32
> >>> -	if (ntp->tv_sec > INT_MAX &&
> >>> -	    sizeof(ltp->tv_sec) != sizeof(ntp->tv_sec))
> >>> +	if (ntp->tv_sec > INT_MAX || ntp->tv_sec < INT_MIN)
> >> This line reads as only tv_sec == INT_MAX case results in non-EOVERFLOW
> >> condition.
> >>
> >
> > should I rewrite it like:
> >
> > 	if (ntp->tv_sec < INT_MIN || ntp->tv_sec > INT_MAX)
> > ?
> 
> I don't see the problem.   Do you mean that the compiler might remove
> this code because the check is tautologically false on 32-bit natives,
> but warn too?

I mean kib@ sentence that line 'reads like', as I'm sure that the code
is correct.
This code does not compile on 32-bit as it under COMPAT_LINUX32.


> 
> The sizeof() comparison is even easier to evaluate at compile time.
> Perhaps it acted a hint to the compiler to not warn.
> 
> Bruce

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