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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8657FC433EF for ; Sat, 22 Jan 2022 02:44:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:CC:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tGvFEb93ViYM8InxEBBsht66YVg4CcLzsbG5ctrhwGQ=; b=rnBiZpZYZu5qmtUGBZwSnjkH2p X/mJyOZD0KHavVUEmHsQjZ6KfgjyzEzzwOCzqWmTielW8Ao1I19Dj0+BivohfHq67x1o/rp80qp7b S2NYfaKjc9OCRlyrIFqCN/n6/gUFMuaCePXEXu3Cxnf2wU1/5cmgG//HtFsaAUIyf1tq5YQIfZEM9 d1zONcNONKxmtrPOr4WGQZQOf6tlGokfxt9SX43cCrnQO9fUfnGKGwNEKUG1tDGG0L8BN+xSXjedA Gy/5MddgI7pwIoANa20N76QNtd1ygpKsIRj7Jv1HnijqpGUMDGCKSckEEyohq1xJQ80S1Z5K+bSOv HFIy+6Eg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nB6NB-00GPue-JL; Sat, 22 Jan 2022 02:43:25 +0000 Received: from szxga01-in.huawei.com ([45.249.212.187]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nB6N7-00GPu7-HN for linux-mtd@lists.infradead.org; Sat, 22 Jan 2022 02:43:23 +0000 Received: from kwepemi100015.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4JggSH0H9VzZfcs; Sat, 22 Jan 2022 10:39:27 +0800 (CST) Received: from kwepemm600019.china.huawei.com (7.193.23.64) by kwepemi100015.china.huawei.com (7.221.188.125) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Sat, 22 Jan 2022 10:43:15 +0800 Received: from [10.174.177.210] (10.174.177.210) by kwepemm600019.china.huawei.com (7.193.23.64) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Sat, 22 Jan 2022 10:43:15 +0800 Subject: Re: [PATCH] mtd: phram: Prevent divide by zero bug in phram_setup() To: Dan Carpenter , Joern Engel CC: Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , , References: <20220121053836.GA27293@kili> From: yangerkun Message-ID: <00cdcbbc-c74e-e7d1-f751-93aac5113eee@huawei.com> Date: Sat, 22 Jan 2022 10:43:14 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20220121053836.GA27293@kili> Content-Language: en-US X-Originating-IP: [10.174.177.210] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm600019.china.huawei.com (7.193.23.64) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220121_184321_800653_F5C32C53 X-CRM114-Status: GOOD ( 17.38 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org Thanks for the fix! Reviewed-by: yangerkun On 2022/1/21 13:38, Dan Carpenter wrote: > The problem is that "erasesize" is a uint32_t type so it might be > non-zero but the truncated "(uint32_t)erasesize" value *is* zero. That > would lead to the divide by zero bug. > > Avoid the bug by delaying the divide until after we have validated > that "erasesize" is reasonable. > > Fixes: dc2b3e5cbc80 ("mtd: phram: use div_u64_rem to stop overwrite len in phram_setup") > Signed-off-by: Dan Carpenter > --- > drivers/mtd/devices/phram.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c > index 6ed6c51fac69..d503821a3e60 100644 > --- a/drivers/mtd/devices/phram.c > +++ b/drivers/mtd/devices/phram.c > @@ -264,16 +264,20 @@ static int phram_setup(const char *val) > } > } > > - if (erasesize) > - div_u64_rem(len, (uint32_t)erasesize, &rem); > - > if (len == 0 || erasesize == 0 || erasesize > len > - || erasesize > UINT_MAX || rem) { > + || erasesize > UINT_MAX) { > parse_err("illegal erasesize or len\n"); > ret = -EINVAL; > goto error; > } > > + div_u64_rem(len, (uint32_t)erasesize, &rem); > + if (rem) { > + parse_err("len is not multiple of erasesize\n"); > + ret = -EINVAL; > + goto error; > + } > + > ret = register_device(name, start, len, (uint32_t)erasesize); > if (ret) > goto error; > ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/