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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF8D9C7EE30 for ; Sun, 26 Feb 2023 03:56:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230183AbjBZD4C (ORCPT ); Sat, 25 Feb 2023 22:56:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230221AbjBZDzl (ORCPT ); Sat, 25 Feb 2023 22:55:41 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1B3B71714E; Sat, 25 Feb 2023 19:55:11 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id EE416B80956; Sun, 26 Feb 2023 03:44:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC7FDC433D2; Sun, 26 Feb 2023 03:44:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677383053; bh=LE6Cuxh0N4Eej+KJKmepjRL+51JfrcQnW1JJGA9cAOk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PM0CfhWT1wXNddcyFftkUKX74V3kaxax7cb5ZeGtCyCxwAZo27ZmSia3L6Ogj3SEV bPv31BxBvVRzwlIGuvs7+/oBLsogrVJIDm43gnFM+qwiZBKMg8/YZCLEWfVGvmdJoN 95yYXAZRQDhv3mL82x5U6V0BTwYVGlf2uf4fSwo5X7RiRNsDigN17Dgh2Qk97miLLl WwwHa5CU7qjymp7BpCuPvJLUAoq7Elf3Gdw//WA6rgNz1FpPEsovoREwk25mPXbELX nZWy32sDIYfKlHvZr8y/X7OvxFiYA8xLu0Bzi2A3Ctqy8akLj4ky66SURfEyUo5SLZ 2XX6FnTq1qz9Q== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Li Nan , Yu Kuai , Tejun Heo , Jens Axboe , Sasha Levin , josef@toxicpanda.com, cgroups@vger.kernel.org, linux-block@vger.kernel.org Subject: [PATCH AUTOSEL 5.10 3/5] blk-iocost: fix divide by 0 error in calc_lcoefs() Date: Sat, 25 Feb 2023 22:44:06 -0500 Message-Id: <20230226034408.774670-3-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230226034408.774670-1-sashal@kernel.org> References: <20230226034408.774670-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Li Nan [ Upstream commit 984af1e66b4126cf145153661cc24c213e2ec231 ] echo max of u64 to cost.model can cause divide by 0 error. # echo 8:0 rbps=18446744073709551615 > /sys/fs/cgroup/io.cost.model divide error: 0000 [#1] PREEMPT SMP RIP: 0010:calc_lcoefs+0x4c/0xc0 Call Trace: ioc_refresh_params+0x2b3/0x4f0 ioc_cost_model_write+0x3cb/0x4c0 ? _copy_from_iter+0x6d/0x6c0 ? kernfs_fop_write_iter+0xfc/0x270 cgroup_file_write+0xa0/0x200 kernfs_fop_write_iter+0x17d/0x270 vfs_write+0x414/0x620 ksys_write+0x73/0x160 __x64_sys_write+0x1e/0x30 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd calc_lcoefs() uses the input value of cost.model in DIV_ROUND_UP_ULL, overflow would happen if bps plus IOC_PAGE_SIZE is greater than ULLONG_MAX, it can cause divide by 0 error. Fix the problem by setting basecost Signed-off-by: Li Nan Signed-off-by: Yu Kuai Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20230117070806.3857142-5-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-iocost.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/block/blk-iocost.c b/block/blk-iocost.c index fb8f959a7f327..9255b642d6adb 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -872,9 +872,14 @@ static void calc_lcoefs(u64 bps, u64 seqiops, u64 randiops, *page = *seqio = *randio = 0; - if (bps) - *page = DIV64_U64_ROUND_UP(VTIME_PER_SEC, - DIV_ROUND_UP_ULL(bps, IOC_PAGE_SIZE)); + if (bps) { + u64 bps_pages = DIV_ROUND_UP_ULL(bps, IOC_PAGE_SIZE); + + if (bps_pages) + *page = DIV64_U64_ROUND_UP(VTIME_PER_SEC, bps_pages); + else + *page = 1; + } if (seqiops) { v = DIV64_U64_ROUND_UP(VTIME_PER_SEC, seqiops); -- 2.39.0