From patchwork Fri Mar 12 00:49:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 12133457 X-Patchwork-Delegate: bpf@iogearbox.net 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 EA8B5C28E88 for ; Fri, 12 Mar 2021 00:50:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D51D764FAD for ; Fri, 12 Mar 2021 00:50:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230192AbhCLAtt (ORCPT ); Thu, 11 Mar 2021 19:49:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52042 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231352AbhCLAtd (ORCPT ); Thu, 11 Mar 2021 19:49:33 -0500 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65722C061574 for ; Thu, 11 Mar 2021 16:49:32 -0800 (PST) Received: by mail-yb1-xb49.google.com with SMTP id 6so27799568ybq.7 for ; Thu, 11 Mar 2021 16:49:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=Y+bQ/FvCUm3fvBgel5uQUEfp5fAIz/0D/2shjtjBBOQ=; b=XH46gyIVQlOmQFd/RmNS2UiHhzUpt2qt03RTF06Xnae6iCcw0dFPqWjKTPco+qP/Zx fB/uJw66ANkZSXLpgPZzsNiuQ09DnyCviGcpTgD8pTRezXmUpwZek+cB7Y/HvGxA8qch dFOUqeeMZ918ZEBhrbuNcNxKi6PRldR02Suyv0Yn8UZyobwAbNbMX7d8KutkSzRsxDGm 0S6hbtJQ8Ws4a+nW+Glvo6IMRSySbHIstPjzQXpwjaBdZ61ql+77Yzbd9C2HqajlQ9bT al24/Uv71xlS2VCq05aPDtCBcnEMCW+8us1rt97YOCFL3l3qREf0N5Bb4Jekm29kn/qK q9Xg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=Y+bQ/FvCUm3fvBgel5uQUEfp5fAIz/0D/2shjtjBBOQ=; b=Y/X1kJ4t7Ld9T5HK/XIwyRhuvmSA6VE/oSAmawmtn6mDFBbQowjVWKlyxzJcluDo54 ZlxU8AN9yzSxuPeCaybS2ez2E9qM5SoNC1q9t8pUlj3WwzRCBaCQCptnw8fewesUwDcZ rQSRTSnC4Im8xgx8iW8Wm+Mzec8VN8ZGgSZHozqB7YXkMdaxeQJjFEONLRuZn+5UZBnv tA5J/AIS/aqUuoeypsnCnf7Pkge4cpGdHgQeNJlFfcqTeo5C80ESFNHktRphGYP2Z54K YswDNnOKhHzUN6dvvxcPY8fSLcfOVUiaNhjRR38Y6oOL7NZTVbCYLAkgg9fgmd/ANtKK d89g== X-Gm-Message-State: AOAM533rcGCjB/KqDdX6cTuLC4f0BVUl8uKoqlH9vAXmDHaOqAbIDLak MboBmkwFJjygZBYF0uIAiFoucOsdvGBMQ481Ij8= X-Google-Smtp-Source: ABdhPJx7qHHoiwHh7Mz2oYX8+DonjBOnAMdcSWoE+4sImbjhV4Eew8XMTramdbIeYBSUSqj6zA5bpTyw6U5L5XSs8WU= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:c86b:8269:af92:55a]) (user=samitolvanen job=sendgmr) by 2002:a25:1d88:: with SMTP id d130mr15900461ybd.446.1615510171706; Thu, 11 Mar 2021 16:49:31 -0800 (PST) Date: Thu, 11 Mar 2021 16:49:08 -0800 In-Reply-To: <20210312004919.669614-1-samitolvanen@google.com> Message-Id: <20210312004919.669614-7-samitolvanen@google.com> Mime-Version: 1.0 References: <20210312004919.669614-1-samitolvanen@google.com> X-Mailer: git-send-email 2.31.0.rc2.261.g7f71774620-goog Subject: [PATCH 06/17] kthread: cfi: disable callback pointer check with modules From: Sami Tolvanen To: Kees Cook Cc: Nathan Chancellor , Nick Desaulniers , Masahiro Yamada , Will Deacon , Jessica Yu , Arnd Bergmann , Tejun Heo , bpf@vger.kernel.org, linux-hardening@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org With CONFIG_CFI_CLANG, a callback function passed to __kthread_queue_delayed_work from a module points to a jump table entry defined in the module instead of the one used in the core kernel, which breaks function address equality in this check: WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); Disable the warning when CFI and modules are enabled. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook --- kernel/kthread.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/kthread.c b/kernel/kthread.c index 1578973c5740..af5fee350586 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -963,7 +963,13 @@ static void __kthread_queue_delayed_work(struct kthread_worker *worker, struct timer_list *timer = &dwork->timer; struct kthread_work *work = &dwork->work; - WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); + /* + * With CFI, timer->function can point to a jump table entry in a module, + * which fails the comparison. Disable the warning if CFI and modules are + * both enabled. + */ + if (!IS_ENABLED(CONFIG_CFI_CLANG) || !IS_ENABLED(CONFIG_MODULES)) + WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); /* * If @delay is 0, queue @dwork->work immediately. This is for