Date: Mon, 3 Apr 2017 12:47:33 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Chagin Dmitry <dchagin@freebsd.org> Cc: Bruce Evans <brde@optusnet.com.au>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r316393 - head/sys/compat/linux Message-ID: <20170403094733.GM43712@kib.kiev.ua> In-Reply-To: <20170402182341.GA50190@mordor.heemeyer.club> References: <201704020746.v327kDSN042840@repo.freebsd.org> <20170402133651.GJ43712@kib.kiev.ua> <20170402163306.GA44865@mordor.heemeyer.club> <20170403035157.X3216@besplex.bde.org> <20170402182341.GA50190@mordor.heemeyer.club>
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On Sun, Apr 02, 2017 at 09:23:41PM +0300, Chagin Dmitry wrote: > 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. I indeed mis-read the context where the checks are done, I thought that the members checked are ints. Please ignore me. > > > > > > 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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