From owner-svn-src-all@freebsd.org Mon May 6 20:35:09 2019 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 618FE15952FF; Mon, 6 May 2019 20:35:09 +0000 (UTC) (envelope-from freebsd@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (br1.CN84in.dnsmgr.net [69.59.192.140]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id B7CEA88AE7; Mon, 6 May 2019 20:35:08 +0000 (UTC) (envelope-from freebsd@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (localhost [127.0.0.1]) by gndrsh.dnsmgr.net (8.13.3/8.13.3) with ESMTP id x46KZ3BG008318; Mon, 6 May 2019 13:35:03 -0700 (PDT) (envelope-from freebsd@gndrsh.dnsmgr.net) Received: (from freebsd@localhost) by gndrsh.dnsmgr.net (8.13.3/8.13.3/Submit) id x46KZ37X008317; Mon, 6 May 2019 13:35:03 -0700 (PDT) (envelope-from freebsd) From: "Rodney W. Grimes" Message-Id: <201905062035.x46KZ37X008317@gndrsh.dnsmgr.net> Subject: Re: svn commit: r347063 - head/sys/kern In-Reply-To: <20190506184502.GA35464@raichu> To: Mark Johnston Date: Mon, 6 May 2019 13:35:03 -0700 (PDT) CC: John Baldwin , src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Reply-To: rgrimes@freebsd.org X-Mailer: ELM [version 2.4ME+ PL121h (25)] MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: B7CEA88AE7 X-Spamd-Bar: ------ Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-6.98 / 15.00]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; REPLY(-4.00)[]; NEURAL_HAM_SHORT(-0.98)[-0.983,0] X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 06 May 2019 20:35:09 -0000 > On Mon, May 06, 2019 at 11:07:18AM -0700, John Baldwin wrote: > > On 5/3/19 2:26 PM, Mark Johnston wrote: > > > Author: markj > > > Date: Fri May 3 21:26:44 2019 > > > New Revision: 347063 > > > URL: https://svnweb.freebsd.org/changeset/base/347063 > > > > > > Log: > > > Disallow excessively small times of day in clock_settime(2). > > > > > > Reported by: syzkaller > > > Reviewed by: cem, kib > > > MFC after: 1 week > > > Sponsored by: The FreeBSD Foundation > > > Differential Revision: https://reviews.freebsd.org/D20151 > > > > > > Modified: > > > head/sys/kern/kern_time.c > > > > > > Modified: head/sys/kern/kern_time.c > > > ============================================================================== > > > --- head/sys/kern/kern_time.c Fri May 3 21:13:09 2019 (r347062) > > > +++ head/sys/kern/kern_time.c Fri May 3 21:26:44 2019 (r347063) > > > @@ -412,7 +412,9 @@ kern_clock_settime(struct thread *td, clockid_t clock_ > > > if (ats->tv_nsec < 0 || ats->tv_nsec >= 1000000000 || > > > ats->tv_sec < 0) > > > return (EINVAL); > > > - if (!allow_insane_settime && ats->tv_sec > 8000ULL * 365 * 24 * 60 * 60) > > > + if (!allow_insane_settime && > > > + (ats->tv_sec > 8000ULL * 365 * 24 * 60 * 60 || > > > + ats->tv_sec < utc_offset())) > > > return (EINVAL); > > > /* XXX Don't convert nsec->usec and back */ > > > TIMESPEC_TO_TIMEVAL(&atv, ats); > > > > Pardon my ignorance, but I can't see why you are checking against utc_offset() > > vs some small constant? None of the discussion in the review mentioned the > > reason for using this particular value, and I didn't see any comparisons > > against utc_offset or kernadjtz in kern_clock_setttime() or settime() that > > would have underflowed or panicked. Can you give a bit more detail on why > > utc_offset() is the lower bound? Thanks. > > I chose it because we subtract utc_offset() from the time passed in to > clock_settime(); see settime_task_func(). That subtraction caused the > underflow that later caused the observed panics. If the above conditional stays could the above go in a block comment near this check please? Doesn't this underflow actually indicate the settime is in the prior day and other stuff needs adjusted? -- Rod Grimes rgrimes@freebsd.org