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 AEAFCC10F0C for ; Thu, 4 Apr 2019 09:18:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 700DA20652 for ; Thu, 4 Apr 2019 09:18:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554369533; bh=HsqZ9DTk/2OYjcIBv7w6lQkkX+QQC/KsdyaPHFp3Us8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=KfVeDbUlgm1fZhT7/6mD55YLbaaHul4zickYIcAiHY/AgoAuZ/z/ECyJSTh4YXqcO HPA3MZozSvfpDqgsG3H1bD6rm0mvba417P8zgh3y2yBjPNODPuxRUjCC9n7SsUufKM joqplWTjxVxeqzgzAzB9canVHHJN3pDCtlzr4hCo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388427AbfDDJSw (ORCPT ); Thu, 4 Apr 2019 05:18:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:60846 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387594AbfDDJSj (ORCPT ); Thu, 4 Apr 2019 05:18:39 -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 0F4E220652; Thu, 4 Apr 2019 09:18:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554369518; bh=HsqZ9DTk/2OYjcIBv7w6lQkkX+QQC/KsdyaPHFp3Us8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gZP528rnWa387QL8ONxiaJ/CmFOOaRqZt/TJ/VrUahIZt9xN55B8OflgLEBAsTzPK P7q5eyN7LSR8j5De7yaO/b34cOdubgPmtGVef1PAJhY9RvizFOeHBzuthiQAwY0W6V rjgsmOYuC1SdTM7Du0a5B1CeqfwEhqvCC9ALq80E= 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 5.0 246/246] bcache: fix potential div-zero error of writeback_rate_p_term_inverse Date: Thu, 4 Apr 2019 10:49:06 +0200 Message-Id: <20190404084627.919536818@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190404084619.236418459@linuxfoundation.org> References: <20190404084619.236418459@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: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 5.0-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 28e0d5a5e25b..e5daf91310f6 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -290,7 +290,9 @@ 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