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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 CEF80C432C2 for ; Wed, 25 Sep 2019 14:31:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9E5792146E for ; Wed, 25 Sep 2019 14:31:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9E5792146E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C371E6B0266; Wed, 25 Sep 2019 10:31:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BC2CE6B026B; Wed, 25 Sep 2019 10:31:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A12D46B026D; Wed, 25 Sep 2019 10:31:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0167.hostedemail.com [216.40.44.167]) by kanga.kvack.org (Postfix) with ESMTP id 700B96B0266 for ; Wed, 25 Sep 2019 10:31:23 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 074657817 for ; Wed, 25 Sep 2019 14:31:23 +0000 (UTC) X-FDA: 75973680846.03.honey75_8070a8ff99f3c X-HE-Tag: honey75_8070a8ff99f3c X-Filterd-Recvd-Size: 6255 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf50.hostedemail.com (Postfix) with ESMTP for ; Wed, 25 Sep 2019 14:31:22 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 5E0FFAE89; Wed, 25 Sep 2019 14:31:19 +0000 (UTC) From: Vlastimil Babka To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Qian Cai , "Kirill A. Shutemov" , Matthew Wilcox , Mel Gorman , Michal Hocko , Vlastimil Babka , Dmitry Vyukov , Walter Wu , Andrey Ryabinin Subject: [PATCH 2/3] mm, debug, kasan: save and dump freeing stack trace for kasan Date: Wed, 25 Sep 2019 16:30:55 +0200 Message-Id: <20190925143056.25853-7-vbabka@suse.cz> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190925143056.25853-1-vbabka@suse.cz> References: <20190925143056.25853-1-vbabka@suse.cz> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The commit 8974558f49a6 ("mm, page_owner, debug_pagealloc: save and dump freeing stack trace") enhanced page_owner to also store freeing stack tra= ce, when debug_pagealloc is also enabled. KASAN would also like to do this [1= ] to improve error reports to debug e.g. UAF issues. This patch therefore intr= oduces a helper config option PAGE_OWNER_FREE_STACK, which is enabled when PAGE_= OWNER and either of DEBUG_PAGEALLOC or KASAN is enabled. Boot-time, the free st= ack saving is enabled when booting a KASAN kernel with page_owner=3Don, or no= n-KASAN kernel with debug_pagealloc=3Don and page_owner=3Don. [1] https://bugzilla.kernel.org/show_bug.cgi?id=3D203967 Suggested-by: Dmitry Vyukov Suggested-by: Walter Wu Suggested-by: Andrey Ryabinin Signed-off-by: Vlastimil Babka Reviewed-by: Andrey Ryabinin --- Documentation/dev-tools/kasan.rst | 4 ++++ mm/Kconfig.debug | 4 ++++ mm/page_owner.c | 31 ++++++++++++++++++------------- 3 files changed, 26 insertions(+), 13 deletions(-) diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/= kasan.rst index b72d07d70239..434e605030e9 100644 --- a/Documentation/dev-tools/kasan.rst +++ b/Documentation/dev-tools/kasan.rst @@ -41,6 +41,10 @@ smaller binary while the latter is 1.1 - 2 times faste= r. Both KASAN modes work with both SLUB and SLAB memory allocators. For better bug detection and nicer reporting, enable CONFIG_STACKTRACE. =20 +To augment reports with last allocation and freeing stack of the physica= l +page, it is recommended to configure kernel also with CONFIG_PAGE_OWNER = =3D y +and boot with page_owner=3Don. + To disable instrumentation for specific files or directories, add a line similar to the following to the respective kernel Makefile: =20 diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index 327b3ebf23bf..1ea247da3322 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -62,6 +62,10 @@ config PAGE_OWNER =20 If unsure, say N. =20 +config PAGE_OWNER_FREE_STACK + def_bool KASAN || DEBUG_PAGEALLOC + depends on PAGE_OWNER + config PAGE_POISONING bool "Poison pages after freeing" select PAGE_POISONING_NO_SANITY if HIBERNATION diff --git a/mm/page_owner.c b/mm/page_owner.c index d3cf5d336ccf..f3aeec78822f 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -24,13 +24,14 @@ struct page_owner { short last_migrate_reason; gfp_t gfp_mask; depot_stack_handle_t handle; -#ifdef CONFIG_DEBUG_PAGEALLOC +#ifdef CONFIG_PAGE_OWNER_FREE_STACK depot_stack_handle_t free_handle; #endif }; =20 static bool page_owner_disabled =3D true; DEFINE_STATIC_KEY_FALSE(page_owner_inited); +static DEFINE_STATIC_KEY_FALSE(page_owner_free_stack); =20 static depot_stack_handle_t dummy_handle; static depot_stack_handle_t failure_handle; @@ -91,6 +92,8 @@ static void init_page_owner(void) register_failure_stack(); register_early_stack(); static_branch_enable(&page_owner_inited); + if (IS_ENABLED(CONFIG_KASAN) || debug_pagealloc_enabled()) + static_branch_enable(&page_owner_free_stack); init_early_allocated_pages(); } =20 @@ -148,11 +151,11 @@ void __reset_page_owner(struct page *page, unsigned= int order) { int i; struct page_ext *page_ext; -#ifdef CONFIG_DEBUG_PAGEALLOC +#ifdef CONFIG_PAGE_OWNER_FREE_STACK depot_stack_handle_t handle =3D 0; struct page_owner *page_owner; =20 - if (debug_pagealloc_enabled()) + if (static_branch_unlikely(&page_owner_free_stack)) handle =3D save_stack(GFP_NOWAIT | __GFP_NOWARN); #endif =20 @@ -161,8 +164,8 @@ void __reset_page_owner(struct page *page, unsigned i= nt order) return; for (i =3D 0; i < (1 << order); i++) { __clear_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags); -#ifdef CONFIG_DEBUG_PAGEALLOC - if (debug_pagealloc_enabled()) { +#ifdef CONFIG_PAGE_OWNER_FREE_STACK + if (static_branch_unlikely(&page_owner_free_stack)) { page_owner =3D get_page_owner(page_ext); page_owner->free_handle =3D handle; } @@ -450,14 +453,16 @@ void __dump_page_owner(struct page *page) stack_trace_print(entries, nr_entries, 0); } =20 -#ifdef CONFIG_DEBUG_PAGEALLOC - handle =3D READ_ONCE(page_owner->free_handle); - if (!handle) { - pr_alert("page_owner free stack trace missing\n"); - } else { - nr_entries =3D stack_depot_fetch(handle, &entries); - pr_alert("page last free stack trace:\n"); - stack_trace_print(entries, nr_entries, 0); +#ifdef CONFIG_PAGE_OWNER_FREE_STACK + if (static_branch_unlikely(&page_owner_free_stack)) { + handle =3D READ_ONCE(page_owner->free_handle); + if (!handle) { + pr_alert("page_owner free stack trace missing\n"); + } else { + nr_entries =3D stack_depot_fetch(handle, &entries); + pr_alert("page last free stack trace:\n"); + stack_trace_print(entries, nr_entries, 0); + } } #endif =20 --=20 2.23.0