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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 6F1DCC4320A for ; Wed, 18 Aug 2021 04:45:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4FE3261076 for ; Wed, 18 Aug 2021 04:45:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237688AbhHREqU (ORCPT ); Wed, 18 Aug 2021 00:46:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54196 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229449AbhHREqS (ORCPT ); Wed, 18 Aug 2021 00:46:18 -0400 Received: from mail-pj1-x1035.google.com (mail-pj1-x1035.google.com [IPv6:2607:f8b0:4864:20::1035]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2D50FC0613CF for ; Tue, 17 Aug 2021 21:45:44 -0700 (PDT) Received: by mail-pj1-x1035.google.com with SMTP id 28-20020a17090a031cb0290178dcd8a4d1so4525847pje.0 for ; Tue, 17 Aug 2021 21:45:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=d9/DksIpIs6eeSb59VhNgqVboYbLOLwWLPZ+ciNIZIg=; b=PV/qqiQgGxjo7nMT7lRvkdKlSW/DEF7UqjsnHuz+aAZZG9j6+yPAiw8ieIE70Z+Z98 PKUktMDBrsZtmYtRWEbmz8SujoA/UZoeuDMyCxBUwg98IeajHLuTwk+an3fKLpdux5Mm zQGr6S7Qj781WqBMWQlUFyCqs8C8+z4HEbhMs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=d9/DksIpIs6eeSb59VhNgqVboYbLOLwWLPZ+ciNIZIg=; b=qH6iQqRVNVY2eMMbaI9aSeqynvXQCP08zA0DNbfhl+VY2dXd4HalIb7/HMUDJ+4XtB kavtRZIpMc9BU6+afQrXfWe4Wc0wOF5gL6AY7oVHbDzhztxj9pJBbiIMn58kGdhToc1x ScujmXd3iufDx+hWkKrIprJqyc6few8MikS9vsctq+5qZZ31KY479LEcP5jz4cuyLufT mp4GpwpvpNg/sGFos9VEs5wsrZu9YEDHQuEiKn8DbXxZTXi6e00XYjjV1P85uWPrAZU5 8EaxIdp9gKPNzuTET+ykQtJvAJO8KtfBzl5WAUQ4+4xn6fhwUS1xXQu9GAIqAurJgbVi 5FaQ== X-Gm-Message-State: AOAM530KRCMKBqiC8i20AQKhTywn1t1aEchamPgcue1r/A2OHh5IOoP5 rZCOCEltrRC7qhF9+gWB5ZI1Og== X-Google-Smtp-Source: ABdhPJy/XoxWVOZ2UsCcNas/NWhjgh6P8UutKplGf8x5Azcw1w0XTjxJKYaESs1MRWejDlfGVNOzEQ== X-Received: by 2002:a17:902:9b87:b029:12c:c3ed:8a1d with SMTP id y7-20020a1709029b87b029012cc3ed8a1dmr5660298plp.7.1629261943752; Tue, 17 Aug 2021 21:45:43 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id r11sm3453850pjd.26.2021.08.17.21.45.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Aug 2021 21:45:43 -0700 (PDT) From: Kees Cook To: Greg Kroah-Hartman Cc: Kees Cook , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] lkdtm/heap: Avoid __alloc_size hint warning Date: Tue, 17 Aug 2021 21:45:40 -0700 Message-Id: <20210818044540.1601664-1-keescook@chromium.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1136; h=from:subject; bh=DDgzTBXYoMrM8vXwihYDk8DwYREB5xfDvDUf2PPGNps=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBhHJB0pkodVpAzd0nyN16uoly1WRFapAVyer9x5KK+ juNFZ4CJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYRyQdAAKCRCJcvTf3G3AJqJND/ 9ChnuYNoWillTscUU0T21tkDrddDuyj5UgPQbz1sk06wv60e98M6w9vLFOwN91KdSjpZvJa7sexKob PYVefnFMAoldAF3UujbKZoqUIhjm0aGVeHNO88L2KfLoZwDAJs6jafzziJkrurnIcyAQAn+Q1k+vAj C7LLAajvyOlLkvP/qshbJP19Hikma47IZWgJS/rvW+nvnMeeemVInlM0jTNg+sNwiO+Gp4GdXALswO XGQLT1Oaz4FXpw2kBzZJzPfgPlCB5H0SFILnfuangtSVUXauFPdjvEkN1XQU/m8TfbtQoNzZnZLfYg WLToMw6PaXjZbaQi0rWhAoouQu2jBtqJWt80bEccgLuft2b1g4rzrse5d5QCeWf/QaB/YKUEpBAWzk NildF2+vSzkxv0+6T2mrEfMrL7wh6AtqjVcL6gqfDKzCWQJ5MPrBxHZXUwth5VXff//6mlaJcTT8yO wo2ekVqk7zgF5L+WnS8YJRd9SR41ecE5SCkFRyl2J+ur91qPCOWXh5v8M1KdrZnpNEkkztmWDkgeUl 0d/oXThqjlaPYnrbXjHl4hD593ucEEpccUFV3Ip8sSvHinZNsa84/Q/vZQ1UsTjrmSzKh8RXBL8mVR QLofjNpvtf0J4x8qGeAczzXAnwgU+wYeCGpX3VGj536RV1j2J5dxkWXmKGSg== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Once __alloc_size hints have been added, the compiler will (correctly!) see this as an overflow. We are, however, trying to test for this condition, so work around it with a volatile int. Signed-off-by: Kees Cook --- drivers/misc/lkdtm/heap.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/misc/lkdtm/heap.c b/drivers/misc/lkdtm/heap.c index 3d9aae5821a0..e59fcbe00ae0 100644 --- a/drivers/misc/lkdtm/heap.c +++ b/drivers/misc/lkdtm/heap.c @@ -12,6 +12,8 @@ static struct kmem_cache *double_free_cache; static struct kmem_cache *a_cache; static struct kmem_cache *b_cache; +static volatile int __offset = 1; + /* * If there aren't guard pages, it's likely that a consecutive allocation will * let us overflow into the second allocation without overwriting something real. @@ -24,7 +26,7 @@ void lkdtm_VMALLOC_LINEAR_OVERFLOW(void) two = vzalloc(PAGE_SIZE); pr_info("Attempting vmalloc linear overflow ...\n"); - memset(one, 0xAA, PAGE_SIZE + 1); + memset(one, 0xAA, PAGE_SIZE + __offset); vfree(two); vfree(one); -- 2.30.2