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=ham 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 11402C4360F for ; Thu, 4 Apr 2019 09:14:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CFF252075E for ; Thu, 4 Apr 2019 09:14:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554369251; bh=/Teq4lSYkIO9wmtcU2gAh9YeGGOTXE8bHmHHf8yvxqk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=M4TmnvsWPw0npzwuojk1Y8U24LlfIAirAykLKzzP8WvalqE0viDLssdoN3NnIKt9W 2vpP6DXudkGsRV7z06TBheMkguKIwSBdhT2FWjTHNtmT2sOPDSE6S7wBndUwEP0+rY D0hPvfDCgDorp4HdZ5WcxZNMerPnCqLr4P2jPGag= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387676AbfDDJOL (ORCPT ); Thu, 4 Apr 2019 05:14:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:54632 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387446AbfDDJOI (ORCPT ); Thu, 4 Apr 2019 05:14:08 -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 A363820643; Thu, 4 Apr 2019 09:14:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554369248; bh=/Teq4lSYkIO9wmtcU2gAh9YeGGOTXE8bHmHHf8yvxqk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rMMTL5kH/kSZNFC/lgm6uA3lR0RbC5ZxBOD/fExMrOLhvv7OHNo+CVx7+bFpkb+SK lewj5eowPaE1K2SMWKbSWQYM5X2rx9mS3S1SuC6iQ2YQ2TUZsJYXuWvHhRVGnqAfal wxqixAi1wWBMcxRsT2Tf8W1SmSy7NZeb/n8g1e9A= 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 5.0 152/246] bcache: fix potential div-zero error of writeback_rate_i_term_inverse Date: Thu, 4 Apr 2019 10:47:32 +0200 Message-Id: <20190404084624.492055626@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 c3b75a2199cdbfc1c335155fe143d842604b1baa ] 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 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 f98cda32065d..28e0d5a5e25b 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -287,7 +287,9 @@ 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); -- 2.19.1