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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 6122BC433ED for ; Sun, 4 Apr 2021 14:18:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 278096120E for ; Sun, 4 Apr 2021 14:18:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230212AbhDDORx (ORCPT ); Sun, 4 Apr 2021 10:17:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39200 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229633AbhDDORx (ORCPT ); Sun, 4 Apr 2021 10:17:53 -0400 Received: from smtp.gentoo.org (mail.gentoo.org [IPv6:2001:470:ea4a:1:5054:ff:fec7:86e4]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9E9ABC061756 for ; Sun, 4 Apr 2021 07:17:48 -0700 (PDT) Received: by sf.home (Postfix, from userid 1000) id 6D96E5A22061; Sun, 4 Apr 2021 15:17:39 +0100 (BST) From: Sergei Trofimovich To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Sergei Trofimovich , linux-mm@kvack.org Subject: [PATCH] mm: page_poison: print page owner info when corruption is caught Date: Sun, 4 Apr 2021 15:17:35 +0100 Message-Id: <20210404141735.2152984-1-slyfox@gentoo.org> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When page_poison detects page corruption it's useful to see who freed a page recently to have a guess where write-after-free corruption happens. After this change corruption report has extra page_owner data. Example report from real corruption: pagealloc: memory corruption e00000014cd61d10: 11 00 00 00 00 00 00 00 30 1d d2 ff ff 0f 00 60 e00000014cd61d20: b0 1d d2 ff ff 0f 00 60 90 fe 1c 00 08 00 00 20 ... CPU: 1 PID: 220402 Comm: cc1plus Not tainted 5.12.0-rc5-00107-g9720c6f59ecf #245 Hardware name: hp server rx3600, BIOS 04.03 04/08/2008 ... Call Trace: [] show_stack+0x90/0xc0 [] dump_stack+0x150/0x1c0 [] __kernel_unpoison_pages+0x410/0x440 [] get_page_from_freelist+0x1460/0x2ca0 [] __alloc_pages_nodemask+0x3c0/0x660 [] alloc_pages_vma+0xb0/0x500 [] __handle_mm_fault+0x1230/0x1fe0 [] handle_mm_fault+0x310/0x4e0 [] ia64_do_page_fault+0x1f0/0xb80 [] ia64_leave_kernel+0x0/0x270 page_owner tracks the page as freed page allocated via order 0, migratetype Movable, gfp_mask 0x100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 37, ts 8173444098740 __reset_page_owner+0x40/0x200 free_pcp_prepare+0x4d0/0x600 free_unref_page+0x20/0x1c0 __put_page+0x110/0x1a0 migrate_pages+0x16d0/0x1dc0 compact_zone+0xfc0/0x1aa0 proactive_compact_node+0xd0/0x1e0 kcompactd+0x550/0x600 kthread+0x2c0/0x2e0 call_payload+0x50/0x80 Here we can see that page was freed by page migration but something managed to write to it afterwards. CC: Andrew Morton CC: linux-mm@kvack.org Signed-off-by: Sergei Trofimovich --- mm/page_poison.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/page_poison.c b/mm/page_poison.c index 65cdf844c8ad..ef2a1eab13d7 100644 --- a/mm/page_poison.c +++ b/mm/page_poison.c @@ -4,6 +4,7 @@ #include #include #include +#include #include #include #include @@ -45,7 +46,7 @@ static bool single_bit_flip(unsigned char a, unsigned char b) return error && !(error & (error - 1)); } -static void check_poison_mem(unsigned char *mem, size_t bytes) +static void check_poison_mem(struct page *page, unsigned char *mem, size_t bytes) { static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10); unsigned char *start; @@ -70,6 +71,7 @@ static void check_poison_mem(unsigned char *mem, size_t bytes) print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start, end - start + 1, 1); dump_stack(); + dump_page_owner(page); } static void unpoison_page(struct page *page) @@ -82,7 +84,7 @@ static void unpoison_page(struct page *page) * that is freed to buddy. Thus no extra check is done to * see if a page was poisoned. */ - check_poison_mem(addr, PAGE_SIZE); + check_poison_mem(page, addr, PAGE_SIZE); kunmap_atomic(addr); } -- 2.31.1