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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 F1722C43466 for ; Mon, 21 Sep 2020 17:13:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A2A3E2085B for ; Mon, 21 Sep 2020 17:13:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600708407; bh=nx2TaoLqWNqyr9nmT07RvYE1xPfejV7fHLR9RhvDxrs=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=ztxv8YVi7FeHJ4K2cWSx9oZd/4QiG/XacVDXQ5hBRgHbo3/mq18Qv0Bxp1k4SrACC Cgd3ZxNM9p0G+TTj0sS3ybjUXImx+k1L2lxy1ESSkTudOMIHmm/JExfUVIImHs0JTN fnBfca/KWk/EtYXx+JmlG1MqzW4zsNCO2E+JMJAA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726913AbgIURN1 (ORCPT ); Mon, 21 Sep 2020 13:13:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:53628 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726818AbgIURN0 (ORCPT ); Mon, 21 Sep 2020 13:13:26 -0400 Received: from paulmck-ThinkPad-P72.home (unknown [50.45.173.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1305520758; Mon, 21 Sep 2020 17:13:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600708406; bh=nx2TaoLqWNqyr9nmT07RvYE1xPfejV7fHLR9RhvDxrs=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=1ijNGgPZsuS/MdRNOo+9S8z8K8msXaiAAXasAViW7Pc1fvHVHsRMQmavi1F5KLtPh L9Re+/yGF1bX9rpvp3gODn97EevX4KNCT1dvqtucDsCJkeffjsyPXqu17zAkpdyhX1 W1lNBAILQoN644xeMWEGZaA7OWAQsGtAc0RFYifk= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id D2C8D352303A; Mon, 21 Sep 2020 10:13:25 -0700 (PDT) Date: Mon, 21 Sep 2020 10:13:25 -0700 From: "Paul E. McKenney" To: Marco Elver Cc: akpm@linux-foundation.org, glider@google.com, hpa@zytor.com, andreyknvl@google.com, aryabinin@virtuozzo.com, luto@kernel.org, bp@alien8.de, catalin.marinas@arm.com, cl@linux.com, dave.hansen@linux.intel.com, rientjes@google.com, dvyukov@google.com, edumazet@google.com, gregkh@linuxfoundation.org, hdanton@sina.com, mingo@redhat.com, jannh@google.com, Jonathan.Cameron@huawei.com, corbet@lwn.net, iamjoonsoo.kim@lge.com, keescook@chromium.org, mark.rutland@arm.com, penberg@kernel.org, peterz@infradead.org, sjpark@amazon.com, tglx@linutronix.de, vbabka@suse.cz, will@kernel.org, x86@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH v3 10/10] kfence: add test suite Message-ID: <20200921171325.GE29330@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20200921132611.1700350-1-elver@google.com> <20200921132611.1700350-11-elver@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200921132611.1700350-11-elver@google.com> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Mon, Sep 21, 2020 at 03:26:11PM +0200, Marco Elver wrote: > Add KFENCE test suite, testing various error detection scenarios. Makes > use of KUnit for test organization. Since KFENCE's interface to obtain > error reports is via the console, the test verifies that KFENCE outputs > expected reports to the console. > > Reviewed-by: Dmitry Vyukov > Co-developed-by: Alexander Potapenko > Signed-off-by: Alexander Potapenko > Signed-off-by: Marco Elver [ . . . ] > +/* Test SLAB_TYPESAFE_BY_RCU works. */ > +static void test_memcache_typesafe_by_rcu(struct kunit *test) > +{ > + const size_t size = 32; > + struct expect_report expect = { > + .type = KFENCE_ERROR_UAF, > + .fn = test_memcache_typesafe_by_rcu, > + }; > + > + setup_test_cache(test, size, SLAB_TYPESAFE_BY_RCU, NULL); > + KUNIT_EXPECT_TRUE(test, test_cache); /* Want memcache. */ > + > + expect.addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY); > + *expect.addr = 42; > + > + rcu_read_lock(); > + test_free(expect.addr); > + KUNIT_EXPECT_EQ(test, *expect.addr, (char)42); > + rcu_read_unlock(); It won't happen very often, but memory really could be freed at this point, especially in CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels ... > + /* No reports yet, memory should not have been freed on access. */ > + KUNIT_EXPECT_FALSE(test, report_available()); ... so the above statement needs to go before the rcu_read_unlock(). > + rcu_barrier(); /* Wait for free to happen. */ But you are quite right that the memory is not -guaranteed- to be freed until we get here. Thanx, Paul