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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 03FA4C433E0 for ; Fri, 12 Mar 2021 12:17:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3A2164FF3 for ; Fri, 12 Mar 2021 12:17:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230521AbhCLMQ6 (ORCPT ); Fri, 12 Mar 2021 07:16:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58682 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230497AbhCLMQ5 (ORCPT ); Fri, 12 Mar 2021 07:16:57 -0500 Received: from mail-qk1-x74a.google.com (mail-qk1-x74a.google.com [IPv6:2607:f8b0:4864:20::74a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7D472C061574 for ; Fri, 12 Mar 2021 04:16:57 -0800 (PST) Received: by mail-qk1-x74a.google.com with SMTP id k68so17955499qke.2 for ; Fri, 12 Mar 2021 04:16:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=lKkSFyfUt4v/K1TZ3S0RPtMBMYYMM41WrxOgRZxr+i0=; b=gJGZNvjry+gw1+ZgyiRQ62ujkPUEFw4uDzOqg2hLxaDjdAvqKra4PKwRCgzEiVdu9k Wf8LlSX/3iIXYKXA1uPrYqvSsxBI0HZ3mDMoaV6UYUNLjFJcH6G64+HGPUsr8SI0iipK lg+6Irj5THH86N+UMxsJ/KjukjGqtq4xgSPK3rFzt2DBW5J5mEo7dIXSTvj8P6xTcqTu 4m01AufPnzboMGl8zVMDot71KxcBkzGJunAp6KSFr+qWxAulb1h2C3d+1Au44nkqVzLs x5F7kOWaNacpNawAPZ4E0hEXArNVaAj3d3vJEijJ3zfvw3fF7psXOldcwIp8edAZR8mG pDMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=lKkSFyfUt4v/K1TZ3S0RPtMBMYYMM41WrxOgRZxr+i0=; b=tItlQ3kf/1IsMouumjSUD3l1PttHmA+1uT1qI18MQ/9tAGgD3qny5pANqraNIFjBMt oPG9mo2Q39VvdE69ZN1nRwJc9gnXwIWYtSXMCcSXnJOn0EUHEuVXnePymhII433PNQx/ ZxJ+L1ORxo2w4D+Y0DQeutBgZTxUBeK7P9OTgUzkRFod8mYXydcDvJCShz+lBp/WswFd zYCdhncf4JIqR9TGA+nxzzQRFMYIU3Mj1N9K/jQkXeRrRExkM+BvaYh8BPoT4h4OKhJK y4m4mtT4SIuAQD/wI9wbwnxB9+n37+pNE4iaByf8z0P5V4sPBObZj1mCtVnrq6D1Zt1d Cq3g== X-Gm-Message-State: AOAM530uzNY9M3XoWRdoNfJPhA5GwPljDaeBHrz+d1tPLyZrPU+t3Dj9 cVs1WbOkDBwfjxbchGYlC8+wIZdqBw== X-Google-Smtp-Source: ABdhPJyvBuVMaYATBlEOlMHkInkkY8IVbtesmiJENmvpJ0bX2KRyf5zY9q6eiq0WVw9Noi4r0ZWGaaAxyQ== X-Received: from elver.muc.corp.google.com ([2a00:79e0:15:13:d5de:d45f:f79c:cb62]) (user=elver job=sendgmr) by 2002:a05:6214:80a:: with SMTP id df10mr12249434qvb.46.1615551416493; Fri, 12 Mar 2021 04:16:56 -0800 (PST) Date: Fri, 12 Mar 2021 13:16:53 +0100 Message-Id: <20210312121653.348518-1-elver@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.31.0.rc2.261.g7f71774620-goog Subject: [PATCH mm] kfence: zero guard page after out-of-bounds access From: Marco Elver To: elver@google.com, akpm@linux-foundation.org Cc: glider@google.com, dvyukov@google.com, andreyknvl@google.com, jannh@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After an out-of-bounds accesses, zero the guard page before re-protecting in kfence_guarded_free(). On one hand this helps make the failure mode of subsequent out-of-bounds accesses more deterministic, but could also prevent certain information leaks. Signed-off-by: Marco Elver --- mm/kfence/core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 3b8ec938470a..f7106f28443d 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -371,6 +371,7 @@ static void kfence_guarded_free(void *addr, struct kfence_metadata *meta, bool z /* Restore page protection if there was an OOB access. */ if (meta->unprotected_page) { + memzero_explicit((void *)ALIGN_DOWN(meta->unprotected_page, PAGE_SIZE), PAGE_SIZE); kfence_protect(meta->unprotected_page); meta->unprotected_page = 0; } -- 2.31.0.rc2.261.g7f71774620-goog