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 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 9FCB1C43381 for ; Mon, 18 Feb 2019 20:33:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6936B21929 for ; Mon, 18 Feb 2019 20:33:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729246AbfBRUdt (ORCPT ); Mon, 18 Feb 2019 15:33:49 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45658 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726831AbfBRUds (ORCPT ); Mon, 18 Feb 2019 15:33:48 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5FB7E85360; Mon, 18 Feb 2019 20:33:48 +0000 (UTC) Received: from segfault.boston.devel.redhat.com (segfault.boston.devel.redhat.com [10.19.60.26]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4238C19C4F; Mon, 18 Feb 2019 20:33:46 +0000 (UTC) From: Jeff Moyer To: Tan Xiaojun Cc: , , , , , Subject: Re: [RFC PATCH] aio: add check for timeout to aviod invalid value References: <1550311021-60612-1-git-send-email-tanxiaojun@huawei.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 Date: Mon, 18 Feb 2019 15:33:46 -0500 In-Reply-To: <1550311021-60612-1-git-send-email-tanxiaojun@huawei.com> (Tan Xiaojun's message of "Sat, 16 Feb 2019 17:57:01 +0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 18 Feb 2019 20:33:48 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Tan Xiaojun writes: > (When I was testing with syzkaller, I found a lot of ubsan problems. Here > is one of them. I am not sure if it needs to be fixed and how it will be > fixed. So I sent this patch to ask your opinion.) > > Syzkaller reported a UBSAN bug below, which was mainly caused by a large > negative number passed to the timeout of the io_getevents system call. > > ================================================================================ > UBSAN: Undefined behaviour in ./include/linux/ktime.h:42:14 > signed integer overflow: > -8427032702788048137 * 1000000000 cannot be represented in type 'long long int' > CPU: 3 PID: 11668 Comm: syz-executor0 Not tainted 4.19.18-514.55.6.9.x86_64+ #1 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 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 > ktime_set include/linux/ktime.h:42 [inline] > timespec64_to_ktime include/linux/ktime.h:78 [inline] > do_io_getevents+0x307/0x390 fs/aio.c:2043 > __do_sys_io_getevents fs/aio.c:2080 [inline] > __se_sys_io_getevents fs/aio.c:2068 [inline] > __x64_sys_io_getevents+0x163/0x250 fs/aio.c:2068 > do_syscall_64+0xc8/0x580 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x462589 > 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:00007fde9b04ec58 EFLAGS: 00000246 ORIG_RAX: 00000000000000d0 > RAX: ffffffffffffffda RBX: 000000000072bf00 RCX: 0000000000462589 > RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: 0000000000000005 R08: 0000000020000100 R09: 0000000000000000 > R10: 0000000020000040 R11: 0000000000000246 R12: 00007fde9b04f6bc > R13: 00000000004bd1f0 R14: 00000000006f6b60 R15: 00000000ffffffff > ================================================================================ > bond0 (unregistering): Released all slaves > > The timeout described in "man io_getevents" does not say whether it > can be negative or not, but as a waiting time, a negative number has > no meaning. So I add check to avoid this case. It's embarrassing that this bug is still present. See, for example, this discussion, started in 2015: https://lore.kernel.org/lkml/CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com/ I could swear it was brought up again since then, but I can't find records of that. > Signed-off-by: Tan Xiaojun > --- > fs/aio.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/fs/aio.c b/fs/aio.c > index aaaaf4d..28e0fa6 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -2078,10 +2078,15 @@ static long do_io_getevents(aio_context_t ctx_id, > struct io_event __user *events, > struct timespec64 *ts) > { > - ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX; > + ktime_t until; > struct kioctx *ioctx = lookup_ioctx(ctx_id); > long ret = -EINVAL; > > + if (ts && !timespec64_valid(ts)) > + return -EINVAL; > + > + until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX; > + > if (likely(ioctx)) { > if (likely(min_nr <= nr && min_nr >= 0)) > ret = read_events(ioctx, min_nr, nr, events, until); Looks good to me. Thanks for fixing this. Reviewed-by: Jeff Moyer