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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E347C43217 for ; Fri, 11 Nov 2022 00:42:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230132AbiKKAmt (ORCPT ); Thu, 10 Nov 2022 19:42:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58984 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229932AbiKKAmr (ORCPT ); Thu, 10 Nov 2022 19:42:47 -0500 Received: from mail-pj1-x1031.google.com (mail-pj1-x1031.google.com [IPv6:2607:f8b0:4864:20::1031]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3C2DA61B8E for ; Thu, 10 Nov 2022 16:42:46 -0800 (PST) Received: by mail-pj1-x1031.google.com with SMTP id k5so3127700pjo.5 for ; Thu, 10 Nov 2022 16:42:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=xM5WNzI0hwRHjliP1X8vOe9pxalT6LKCbo/mWi3YSJs=; b=Ks0k/pf8S/S1HZNwKLbh8GafqB1bWlwq1sI/v9pfDxFYhNglaLAjwpun9WjaZ3IP45 DxKlrmbh/25Er18wbqq1jIHdLjB0X+A0g0SODBnycheHV2whn6s/WYuKBA4w2Q0wG91M f+mG8bvckQFAkHwQ3N385LuwERVCtA9iXj4qo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=xM5WNzI0hwRHjliP1X8vOe9pxalT6LKCbo/mWi3YSJs=; b=A8Gna+pFGzEkY1SIfXx2muQpL0j7D2BqKmt6xIZKO6NqUVfP/aqrEmN+7OT0BGruv4 uBgc/04R4dG7G8Ua8KlXWezr7sQ0dggZoz1lhaH1/UyMx4DpN/jWmI76VqTuN+6Wv9Zb QkO63sXXmFbZQy6Jm77MhHxHt6DNSW/N5hWmwTEkG2z9Usb2a5mqxJcNGaNAdlhz7d1D rVHrbqRfv7/2nEUfst/AA5Mv1QrdQOVBNvfmnMejOXpGjUGMKJJMqV4N1ce3FzgHUIKL IzWwRDdxnmFz7TlMquyH+ifi/RO5JIRoP3YTKYIZWe7xJOtWxIP7uxvzfNjxLsUnIo81 tV+Q== X-Gm-Message-State: ANoB5pn4w0GgCdfOsPyy8r+6sYHOuzwTgsh59PW8dYqfiyAtcPSRho/6 QxFqrv+OCaq3AIgLvCVNZalqXA== X-Google-Smtp-Source: AA0mqf4lsQyzaHXXZR1h9k1dQs/5NsV//w58zMbDuUA6cVJJlf1B6++qWdvFLSorlO2Qcc0M6PwT3Q== X-Received: by 2002:a17:902:bd8e:b0:186:8398:350 with SMTP id q14-20020a170902bd8e00b0018683980350mr214085pls.6.1668127365713; Thu, 10 Nov 2022 16:42:45 -0800 (PST) Received: from google.com ([240f:75:7537:3187:8d55:c60d:579d:741c]) by smtp.gmail.com with ESMTPSA id q90-20020a17090a756300b001faf7a88138sm375216pjk.42.2022.11.10.16.42.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Nov 2022 16:42:45 -0800 (PST) Date: Fri, 11 Nov 2022 09:42:38 +0900 From: Sergey Senozhatsky To: coverity-bot Cc: Alexey Romanov , linux-kernel@vger.kernel.org, Nick Terrell , Minchan Kim , Suleiman Souhlal , Nitin Gupta , Jens Axboe , Nhat Pham , Andrew Morton , linux-block@vger.kernel.org, "Gustavo A. R. Silva" , linux-next@vger.kernel.org, linux-hardening@vger.kernel.org, Sergey Senozhatsky Subject: Re: Coverity: zram_recompress(): OVERRUN Message-ID: References: <202211100847.388C61B3@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (22/11/11 09:37), Sergey Senozhatsky wrote: > On (22/11/10 08:47), coverity-bot wrote: > [..] > > 1704 class_index_old = zs_lookup_class_index(zram->mem_pool, comp_len_old); > > 1705 /* > > 1706 * Iterate the secondary comp algorithms list (in order of priority) > > 1707 * and try to recompress the page. > > 1708 */ > > 1709 for (; prio < prio_max; prio++) { > > vvv CID 1527270: (OVERRUN) > > vvv Overrunning array "zram->comps" of 4 8-byte elements at element index 4 (byte offset 39) using index "prio" (which evaluates to 4). > > 1710 if (!zram->comps[prio]) > > 1711 continue; > > 1712 > > 1713 /* > > 1714 * Skip if the object is already re-compressed with a higher > > 1715 * priority algorithm (or same algorithm). > > prio_max is always limited and max value it can have is 4 (ZRAM_MAX_COMPS). > Depending on use case we can limit prio_max even to lower values. > > So we have > > for (; prio < 4; prio++) { > foo = comps[prio]; > } > > I don't see how prio can be 4 inside of this loop. Kees, if we do something like this will it make coverity happy? --- diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 9d33801e8ba8..e67a124f2e88 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1706,6 +1706,7 @@ static int zram_recompress(struct zram *zram, u32 index, struct page *page, * Iterate the secondary comp algorithms list (in order of priority) * and try to recompress the page. */ + prio_max = min(prio_max, ZRAM_MAX_COMPS); for (; prio < prio_max; prio++) { if (!zram->comps[prio]) continue;