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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, T_DKIMWL_WL_HIGH,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 805B0C004C9 for ; Tue, 7 May 2019 05:57:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5032A2054F for ; Tue, 7 May 2019 05:57:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557208621; bh=9cO+/aT9CElXUbD+6b8Ci49IlANqm7qYkIfp6dh7t+Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OTOd3WA3CY9Q+WxMo4s3GFI0a1hkH6C4edwVmlSNnb3APwpe1o5L7m1k3F6VM0bfW PzFVRyaA8l0dwI0MVv8Q3R1B/LcttnnuxkJNUcFWSk1yBZHTcq+UFGDq2aZsDUGlcV /NFCxb6s9yBgiY9rDLHYTuiRMx0Or6jnfZShx2h8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728610AbfEGF5A (ORCPT ); Tue, 7 May 2019 01:57:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:57520 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727539AbfEGFhr (ORCPT ); Tue, 7 May 2019 01:37:47 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D18AE205ED; Tue, 7 May 2019 05:37:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557207466; bh=9cO+/aT9CElXUbD+6b8Ci49IlANqm7qYkIfp6dh7t+Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wIoM8eaeS2aSxgY0sT0d9SlJzxuMdxCbfuCU//Co3MNSSNpfEB7cj9V6mxmNR2qXD UM1Znv2ZIrTMg0UeqKc8pOZIh4vhJ7PTR67YdPKQ+v9L7THVEQdaivBJdC7UlwLrXV wVw+P8qdOUMZFR43AeIFs+k7SSVJ4pZHvDSEAIlk= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Qian Cai , Borislav Petkov , Catalin Marinas , Andy Lutomirski , Brijesh Singh , Dave Hansen , "H. Peter Anvin" , Ingo Molnar , Peter Zijlstra , Thomas Gleixner , x86-ml , Sasha Levin Subject: [PATCH AUTOSEL 4.19 58/81] x86/mm: Fix a crash with kmemleak_scan() Date: Tue, 7 May 2019 01:35:29 -0400 Message-Id: <20190507053554.30848-58-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190507053554.30848-1-sashal@kernel.org> References: <20190507053554.30848-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Qian Cai [ Upstream commit 0d02113b31b2017dd349ec9df2314e798a90fa6e ] The first kmemleak_scan() call after boot would trigger the crash below because this callpath: kernel_init free_initmem mem_encrypt_free_decrypted_mem free_init_pages unmaps memory inside the .bss when DEBUG_PAGEALLOC=y. kmemleak_init() will register the .data/.bss sections and then kmemleak_scan() will scan those addresses and dereference them looking for pointer references. If free_init_pages() frees and unmaps pages in those sections, kmemleak_scan() will crash if referencing one of those addresses: BUG: unable to handle kernel paging request at ffffffffbd402000 CPU: 12 PID: 325 Comm: kmemleak Not tainted 5.1.0-rc4+ #4 RIP: 0010:scan_block Call Trace: scan_gray_list kmemleak_scan kmemleak_scan_thread kthread ret_from_fork Since kmemleak_free_part() is tolerant to unknown objects (not tracked by kmemleak), it is fine to call it from free_init_pages() even if not all address ranges passed to this function are known to kmemleak. [ bp: Massage. ] Fixes: b3f0907c71e0 ("x86/mm: Add .bss..decrypted section to hold shared variables") Signed-off-by: Qian Cai Signed-off-by: Borislav Petkov Reviewed-by: Catalin Marinas Cc: Andy Lutomirski Cc: Brijesh Singh Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: x86-ml Link: https://lkml.kernel.org/r/20190423165811.36699-1-cai@lca.pw Signed-off-by: Sasha Levin --- arch/x86/mm/init.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index d883869437b5..fb5f29c60019 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -6,6 +6,7 @@ #include /* for max_low_pfn */ #include #include +#include #include #include @@ -767,6 +768,11 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end) if (debug_pagealloc_enabled()) { pr_info("debug: unmapping init [mem %#010lx-%#010lx]\n", begin, end - 1); + /* + * Inform kmemleak about the hole in the memory since the + * corresponding pages will be unmapped. + */ + kmemleak_free_part((void *)begin, end - begin); set_memory_np(begin, (end - begin) >> PAGE_SHIFT); } else { /* -- 2.20.1