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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 2CD36C43387 for ; Tue, 15 Jan 2019 16:41:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EFB2720859 for ; Tue, 15 Jan 2019 16:41:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547570510; bh=189SOiM//FkibmunF8t7nwP2CsKXLbOAWpl9wbCdANU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=yNXJzITKIbkcohPVUUfi163nwdsBl6pUKMX02bnLMNisOg1QF6Hn2GQ6QipFTzfjk HI01ZFNlFtJtJLfoUzrlpdtxoIILkv2vxfr/u3MtA3X04Y6yl/SDgArtYziDlrXAGm a5s0W0ci3S6wAW3M6/AwU4fNG6QUD3CeEdj8nu04= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732873AbfAOQlt (ORCPT ); Tue, 15 Jan 2019 11:41:49 -0500 Received: from mail.kernel.org ([198.145.29.99]:58556 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732860AbfAOQlp (ORCPT ); Tue, 15 Jan 2019 11:41:45 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (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 A774F20873; Tue, 15 Jan 2019 16:41:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547570504; bh=189SOiM//FkibmunF8t7nwP2CsKXLbOAWpl9wbCdANU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q7+NB3D5D0l5sKfYqhM7XXzj7P/5orSPXztZgRDeZckXGDk0NkXzkMbfS6ZuDT+Z9 9Fw6c3V12mKMPapwCyz24McrXzmeM0iCzyanbC96yjFEwDRaVpAGjut5bsaRC4qreH gdy1iafK1rqTWTU9CJ+eot1jdpLVABPY3FnYE3bI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Qian Cai , Kees Cook , Andrew Morton , Linus Torvalds Subject: [PATCH 4.19 19/50] mm/usercopy.c: no check page span for stack objects Date: Tue, 15 Jan 2019 17:35:55 +0100 Message-Id: <20190115154911.052979872@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190115154909.933241945@linuxfoundation.org> References: <20190115154909.933241945@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Qian Cai commit 7bff3c06997374fb9b9991536a547b840549a813 upstream. It is easy to trigger this with CONFIG_HARDENED_USERCOPY_PAGESPAN=y, usercopy: Kernel memory overwrite attempt detected to spans multiple pages (offset 0, size 23)! kernel BUG at mm/usercopy.c:102! For example, print_worker_info char name[WQ_NAME_LEN] = { }; char desc[WORKER_DESC_LEN] = { }; probe_kernel_read(name, wq->name, sizeof(name) - 1); probe_kernel_read(desc, worker->desc, sizeof(desc) - 1); __copy_from_user_inatomic check_object_size check_heap_object check_page_span This is because on-stack variables could cross PAGE_SIZE boundary, and failed this check, if (likely(((unsigned long)ptr & (unsigned long)PAGE_MASK) == ((unsigned long)end & (unsigned long)PAGE_MASK))) ptr = FFFF889007D7EFF8 end = FFFF889007D7F00E Hence, fix it by checking if it is a stack object first. [keescook@chromium.org: improve comments after reorder] Link: http://lkml.kernel.org/r/20190103165151.GA32845@beast Link: http://lkml.kernel.org/r/20181231030254.99441-1-cai@lca.pw Signed-off-by: Qian Cai Signed-off-by: Kees Cook Acked-by: Kees Cook Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/usercopy.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -247,7 +247,8 @@ static DEFINE_STATIC_KEY_FALSE_RO(bypass /* * Validates that the given object is: * - not bogus address - * - known-safe heap or stack object + * - fully contained by stack (or stack frame, when available) + * - fully within SLAB object (or object whitelist area, when available) * - not in kernel text */ void __check_object_size(const void *ptr, unsigned long n, bool to_user) @@ -262,9 +263,6 @@ void __check_object_size(const void *ptr /* Check for invalid addresses. */ check_bogus_address((const unsigned long)ptr, n, to_user); - /* Check for bad heap object. */ - check_heap_object(ptr, n, to_user); - /* Check for bad stack object. */ switch (check_stack_object(ptr, n)) { case NOT_STACK: @@ -282,6 +280,9 @@ void __check_object_size(const void *ptr usercopy_abort("process stack", NULL, to_user, 0, n); } + /* Check for bad heap object. */ + check_heap_object(ptr, n, to_user); + /* Check for object in kernel to avoid text exposure. */ check_kernel_text_object((const unsigned long)ptr, n, to_user); }