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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 8A5EFC10F0C for ; Thu, 4 Apr 2019 09:34:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5EECE205F4 for ; Thu, 4 Apr 2019 09:34:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554370454; bh=SzXhmpQOktA0XK80I1zBgGCtw3HvpI1Jmek0Q6Qb0+0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=y1Wl/IaJf9XdeLQGee0Ipyuf8c9EYXAwmZMxlB6NPgqA+l+sU5yh7qHatc25eJc7a ok054wJmIqELmb9/Sh6jLeNja4VEXgMYb/pLaz19OGVFnv5wbhtMs2WbN2y4TWnKDJ 7VogQJVo/79SBbrzYZvit8kZyj6BfpUhlNMfpFNc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732523AbfDDJHe (ORCPT ); Thu, 4 Apr 2019 05:07:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:46374 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732485AbfDDJHe (ORCPT ); Thu, 4 Apr 2019 05:07:34 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0C8F5218D4; Thu, 4 Apr 2019 09:07:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554368853; bh=SzXhmpQOktA0XK80I1zBgGCtw3HvpI1Jmek0Q6Qb0+0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hmKEArm8jDhXi3NJIntbjKXu+G5tNZSqA8zlsW8pi0rk4nVRUc2A7nogr2tqTSYZw UR4YmZuok4yVQhd4CHKtez8icZfU1CAS3EEPo2Np2tn/AhUCH33WPCBOoI31DkByWz WgfmSJeG1WnFkJrGDhniWxOG9P/4GjfoPipIgrQQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Coly Li , Jens Axboe , Sasha Levin Subject: [PATCH 4.19 186/187] bcache: fix potential div-zero error of writeback_rate_p_term_inverse Date: Thu, 4 Apr 2019 10:48:43 +0200 Message-Id: <20190404084611.875407024@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190404084603.119654039@linuxfoundation.org> References: <20190404084603.119654039@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 5b5fd3c94eef69dcfaa8648198e54c92e5687d6d ] Current code already uses d_strtoul_nonzero() to convert input string to an unsigned integer, to make sure writeback_rate_p_term_inverse won't be zero value. But overflow may happen when converting input string to an unsigned integer value by d_strtoul_nonzero(), then dc->writeback_rate_p_term_inverse can still be set to 0 even if the sysfs file input value is not zero, e.g. 4294967296 (a.k.a UINT_MAX+1). If dc->writeback_rate_p_term_inverse is set to 0, it might cause a dev-zero error in following code from __update_writeback_rate(), int64_t proportional_scaled = div_s64(error, dc->writeback_rate_p_term_inverse); This patch replaces d_strtoul_nonzero() by sysfs_strtoul_clamp() and limit the value range in [1, UINT_MAX]. Then the unsigned integer overflow and dev-zero error can be avoided. Signed-off-by: Coly Li Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/md/bcache/sysfs.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c index 503ad954ccc0..d9481640b3e1 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -286,7 +286,9 @@ STORE(__cached_dev) sysfs_strtoul_clamp(writeback_rate_i_term_inverse, dc->writeback_rate_i_term_inverse, 1, UINT_MAX); - d_strtoul_nonzero(writeback_rate_p_term_inverse); + sysfs_strtoul_clamp(writeback_rate_p_term_inverse, + dc->writeback_rate_p_term_inverse, + 1, UINT_MAX); d_strtoul_nonzero(writeback_rate_minimum); sysfs_strtoul_clamp(io_error_limit, dc->error_limit, 0, INT_MAX); -- 2.19.1