From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 63A32C43381 for ; Wed, 27 Feb 2019 03:21:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F2FA218D0 for ; Wed, 27 Feb 2019 03:21:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729596AbfB0DVC (ORCPT ); Tue, 26 Feb 2019 22:21:02 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:43178 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729128AbfB0DVB (ORCPT ); Tue, 26 Feb 2019 22:21:01 -0500 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id C60F499E8551345B2B1E for ; Wed, 27 Feb 2019 11:20:59 +0800 (CST) Received: from [127.0.0.1] (10.184.52.56) by DGGEMS407-HUB.china.huawei.com (10.3.19.207) with Microsoft SMTP Server id 14.3.408.0; Wed, 27 Feb 2019 11:20:54 +0800 Subject: Re: [RFC PATCH] posix-cpu-timers: Avoid undefined behaviour in timespec64_to_ns() To: Deepa Dinamani CC: Thomas Gleixner , Arnd Bergmann , "Linux Kernel Mailing List" References: <1551233212-42022-1-git-send-email-wangxiongfeng2@huawei.com> From: Xiongfeng Wang Message-ID: Date: Wed, 27 Feb 2019 11:20:26 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.184.52.56] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/2/27 10:38, Deepa Dinamani wrote: > On Tue, Feb 26, 2019 at 6:07 PM Xiongfeng Wang > wrote: >> >> When I ran Syzkaller testsuite, I got the following call trace. >> ================================================================================ >> UBSAN: Undefined behaviour in ./include/linux/time64.h:120:27 >> signed integer overflow: >> 8243129037239968815 * 1000000000 cannot be represented in type 'long long int' >> CPU: 5 PID: 28854 Comm: syz-executor.1 Not tainted 4.19.24 #4 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.0-0-g63451fca13-prebuilt.qemu-project.org 04/01/2014 >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0xca/0x13e lib/dump_stack.c:113 >> ubsan_epilogue+0xe/0x81 lib/ubsan.c:159 >> handle_overflow+0x193/0x1e2 lib/ubsan.c:190 >> timespec64_to_ns include/linux/time64.h:120 [inline] >> posix_cpu_timer_set+0x95a/0xb70 kernel/time/posix-cpu-timers.c:687 >> do_timer_settime+0x198/0x2a0 kernel/time/posix-timers.c:892 >> __do_sys_timer_settime kernel/time/posix-timers.c:918 [inline] >> __se_sys_timer_settime kernel/time/posix-timers.c:904 [inline] >> __x64_sys_timer_settime+0x18d/0x260 kernel/time/posix-timers.c:904 >> do_syscall_64+0xc8/0x580 arch/x86/entry/common.c:290 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe >> RIP: 0033:0x462eb9 >> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 >> RSP: 002b:00007f14e4127c58 EFLAGS: 00000246 ORIG_RAX: 00000000000000df >> RAX: ffffffffffffffda RBX: 000000000073bfa0 RCX: 0000000000462eb9 >> RDX: 0000000020000080 RSI: 0000000000000000 RDI: 0000000000000000 >> RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f14e41286bc >> R13: 00000000004c54cc R14: 0000000000704278 R15: 00000000ffffffff >> ================================================================================ >> >> This patch use 'timespec64_to_ktime()' to limit 'tv_sec' to avoid >> overflow. >> >> Signed-off-by: Xiongfeng Wang >> --- >> kernel/time/posix-cpu-timers.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c >> index 80f9552..f7e3929 100644 >> --- a/kernel/time/posix-cpu-timers.c >> +++ b/kernel/time/posix-cpu-timers.c >> @@ -684,7 +684,7 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, >> * Install the new reload setting, and >> * set up the signal and overrun bookkeeping. >> */ >> - timer->it.cpu.incr = timespec64_to_ns(&new->it_interval); >> + timer->it.cpu.incr = ktime_to_ns(timespec64_to_ktime(new->it_interval)); >> timer->it_interval = ns_to_ktime(timer->it.cpu.incr); >> >> /* > > This seems like a similar bug as the other one > https://lkml.org/lkml/2019/2/24/214. Maybe it makes sense here also to > do some bounds checking when we get the userspace parameter. > This patch just saturates the value. Thanks for your advice. I will send another version. Thanks, Xiongfeng > > -Deepa > > . >