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 763D5C64ED6 for ; Sun, 26 Feb 2023 04:08:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229703AbjBZEIl (ORCPT ); Sat, 25 Feb 2023 23:08:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36932 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229486AbjBZEIj (ORCPT ); Sat, 25 Feb 2023 23:08:39 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67EBF6A57; Sat, 25 Feb 2023 20:08:38 -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 4FF3CB80B8A; Sun, 26 Feb 2023 03:44:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A2BFC433EF; Sun, 26 Feb 2023 03:44:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677383044; bh=nXU1mIcE80gCuXpTLG5b3uYjUUQu4yGjMNHvMqJDQyc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LGLVJjQjHJJRYqoX55ITpKdOqnF+zVdiSt8GSHaCwhO1eV4eyXZm6Shoze2WBzocW G4Z9LtZ9+GFNxwFwBh30sV9nYiWb7CgRXlVsnFwkzUr8BLuIOuaWF68m7Rn3ZkQXDj C8c+8eeZs9moAiJVyihSMDJ+P8z0g3xC7EJw5mMNEcdIrbTNa1/PR1BW1gzSDi/ztf akFw3V4mm/BB9fdP6n5fH/QubIfJT+jlerW21kMDpizmfmHrziLHGtPxjWKXmxEaqQ Y+JuXGi3tqjfmFfdiAquEc86U5KrwdW4NTXckjo59kbqUKO22KWq8Ecs/FUcM+K/D0 6Fh7qfhm/5+xA== 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 5.15 3/6] blk-iocost: fix divide by 0 error in calc_lcoefs() Date: Sat, 25 Feb 2023 22:43:55 -0500 Message-Id: <20230226034359.773806-3-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230226034359.773806-1-sashal@kernel.org> References: <20230226034359.773806-1-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 069193dee95b0..bd7e9ffa5d401 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -870,9 +870,14 @@ 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