From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-sn1nam01on0093.outbound.protection.outlook.com ([104.47.32.93]:10176 "EHLO NAM01-SN1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729624AbeIQIca (ORCPT ); Mon, 17 Sep 2018 04:32:30 -0400 From: Sasha Levin To: "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" CC: Thomas Gleixner , John Stultz , Sasha Levin Subject: [PATCH AUTOSEL 4.4 22/43] alarmtimer: Prevent overflow for relative nanosleep Date: Mon, 17 Sep 2018 03:05:02 +0000 Message-ID: <20180917030445.484-22-alexander.levin@microsoft.com> References: <20180917030445.484-1-alexander.levin@microsoft.com> In-Reply-To: <20180917030445.484-1-alexander.levin@microsoft.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org List-ID: From: Thomas Gleixner [ Upstream commit 5f936e19cc0ef97dbe3a56e9498922ad5ba1edef ] Air Icy reported: UBSAN: Undefined behaviour in kernel/time/alarmtimer.c:811:7 signed integer overflow: 1529859276030040771 + 9223372036854775807 cannot be represented in type '= long long int' Call Trace: alarm_timer_nsleep+0x44c/0x510 kernel/time/alarmtimer.c:811 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1235 [inline] __se_sys_clock_nanosleep kernel/time/posix-timers.c:1213 [inline] __x64_sys_clock_nanosleep+0x326/0x4e0 kernel/time/posix-timers.c:1213 do_syscall_64+0xb8/0x3a0 arch/x86/entry/common.c:290 alarm_timer_nsleep() uses ktime_add() to add the current time and the relative expiry value. ktime_add() has no sanity checks so the addition can overflow when the relative timeout is large enough. Use ktime_add_safe() which has the necessary sanity checks in place and limits the result to the valid range. Fixes: 9a7adcf5c6de ("timers: Posix interface for alarm-timers") Reported-by: Team OWL337 Signed-off-by: Thomas Gleixner Cc: John Stultz Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1807020926360.1595@nanos.te= c.linutronix.de Signed-off-by: Sasha Levin --- kernel/time/alarmtimer.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index 6fcc367ad531..e78480b81f8d 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -773,7 +773,8 @@ static int alarm_timer_nsleep(const clockid_t which_clo= ck, int flags, /* Convert (if necessary) to absolute time */ if (flags !=3D TIMER_ABSTIME) { ktime_t now =3D alarm_bases[type].gettime(); - exp =3D ktime_add(now, exp); + + exp =3D ktime_add_safe(now, exp); } =20 if (alarmtimer_do_nsleep(&alarm, exp)) --=20 2.17.1