From patchwork Mon Feb 21 08:49:47 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 544687 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C66F6C433EF for ; Mon, 21 Feb 2022 09:55:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352082AbiBUJzb (ORCPT ); Mon, 21 Feb 2022 04:55:31 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:57300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352073AbiBUJzO (ORCPT ); Mon, 21 Feb 2022 04:55:14 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C6D0387BB; Mon, 21 Feb 2022 01:24:13 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A125C60FCC; Mon, 21 Feb 2022 09:24:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 897EEC340E9; Mon, 21 Feb 2022 09:24:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1645435452; bh=BNVmtUYVnmuinax3C7ACSj9zjInJX74bgTglaPhnYKw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XkreUG9hhBsPiQP7hCson7YUjdeIGX85lm8LXW+4hCpN3n+RHJnC26lLKARhrUTwc wpqTZyg56+prnsVSUY1Iu7yecZ6IISatNeHf5IPZou2E51ycyyly3X/L/LwtaZq3B/ J0JxBAdiMLl4UBIxiYTKLJkCJ7X6kkYm0m1uU1ug= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dan Carpenter , Miquel Raynal Subject: [PATCH 5.16 168/227] mtd: phram: Prevent divide by zero bug in phram_setup() Date: Mon, 21 Feb 2022 09:49:47 +0100 Message-Id: <20220221084940.406240823@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220221084934.836145070@linuxfoundation.org> References: <20220221084934.836145070@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Dan Carpenter commit 3e3765875b1b8864898603768fd5c93eeb552211 upstream. The problem is that "erasesize" is a uint64_t type so it might be non-zero but the lower 32 bits are zero so when it's truncated, "(uint32_t)erasesize", then that value is zero. This leads to a divide by zero bug. Avoid the bug by delaying the divide until after we have validated that "erasesize" is non-zero and within the uint32_t range. Fixes: dc2b3e5cbc80 ("mtd: phram: use div_u64_rem to stop overwrite len in phram_setup") Signed-off-by: Dan Carpenter Signed-off-by: Miquel Raynal Link: https://lore.kernel.org/linux-mtd/20220121115505.GI1978@kadam Signed-off-by: Greg Kroah-Hartman --- drivers/mtd/devices/phram.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) --- a/drivers/mtd/devices/phram.c +++ b/drivers/mtd/devices/phram.c @@ -264,15 +264,19 @@ 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)