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

[Bruce Evans]

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?

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

Bruce