From patchwork Sat Feb 9 04:53:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Coly Li X-Patchwork-Id: 10804115 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5824C922 for ; Sat, 9 Feb 2019 04:54:03 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4802228775 for ; Sat, 9 Feb 2019 04:54:03 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3B04928852; Sat, 9 Feb 2019 04:54:03 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DFF1528775 for ; Sat, 9 Feb 2019 04:54:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726914AbfBIEyC (ORCPT ); Fri, 8 Feb 2019 23:54:02 -0500 Received: from mx2.suse.de ([195.135.220.15]:57874 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726222AbfBIEyC (ORCPT ); Fri, 8 Feb 2019 23:54:02 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 17EECABA1; Sat, 9 Feb 2019 04:54:01 +0000 (UTC) From: Coly Li To: axboe@kernel.dk Cc: linux-bcache@vger.kernel.org, linux-block@vger.kernel.org, Coly Li Subject: [PATCH 13/19] bcache: fix potential div-zero error of writeback_rate_i_term_inverse Date: Sat, 9 Feb 2019 12:53:05 +0800 Message-Id: <20190209045311.15677-14-colyli@suse.de> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190209045311.15677-1-colyli@suse.de> References: <20190209045311.15677-1-colyli@suse.de> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP dc->writeback_rate_i_term_inverse can be set via sysfs interface. It is in type unsigned int, and convert from input string by d_strtoul(). The problem is d_strtoul() does not check valid range of the input, if 4294967296 is written into sysfs file writeback_rate_i_term_inverse, an overflow of unsigned integer will happen and value 0 is set to dc->writeback_rate_i_term_inverse. In writeback.c:__update_writeback_rate(), there are following lines of code, integral_scaled = div_s64(dc->writeback_rate_integral, dc->writeback_rate_i_term_inverse); If dc->writeback_rate_i_term_inverse is set to 0 via sysfs interface, a div-zero error might be triggered in the above code. Therefore we need to add a range limitation in the sysfs interface, this is what this patch does, use sysfs_stroul_clamp() to replace d_strtoul() and restrict the input range in [1, UINT_MAX]. Signed-off-by: Coly Li --- 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 e4519326594f..0fad46d3a8bd 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -302,7 +302,9 @@ STORE(__cached_dev) sysfs_strtoul_clamp(writeback_rate_update_seconds, dc->writeback_rate_update_seconds, 1, WRITEBACK_RATE_UPDATE_SECS_MAX); - d_strtoul(writeback_rate_i_term_inverse); + 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); d_strtoul_nonzero(writeback_rate_minimum);