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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 9C6B9C432C3 for ; Sat, 16 Nov 2019 16:06:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 625462089D for ; Sat, 16 Nov 2019 16:06:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573920373; bh=XRbu216x41VlCbMrwQejgg8e7awRwMdwlAm6BBlFN/k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=KVssT8O6EIwLv422WjJKYhbPn2V/SbLKUD3vPugh3Eqrq5ERi1TRPRnAZRh7PS3vz u9DoqU24mCy2bjYRCcAsdOsgkRS/HvkwtcR1Phzmnzv8Z+L2OPPZrVdT6yoP/QUKy0 daPnQXejIUvZ/yt/O8hG9CHqgtPtoxzcEZKrDOAE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728762AbfKPPu7 (ORCPT ); Sat, 16 Nov 2019 10:50:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:58784 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730570AbfKPPug (ORCPT ); Sat, 16 Nov 2019 10:50:36 -0500 Received: from sasha-vm.mshome.net (unknown [50.234.116.4]) (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 CE94E20729; Sat, 16 Nov 2019 15:50:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573919436; bh=XRbu216x41VlCbMrwQejgg8e7awRwMdwlAm6BBlFN/k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y/9olmtIKOjkubydXzt6BJlDFyVJV7M8d5wpgBBKTYuo+4yPPP7txi4I5kyVv74I4 YkeGtTXiDR5I4KrCY67d2aI4oEZ15j4uOf3hI1bnrEqYqOhLqGQRlmfD/PWbiNOfiy fa4+fAnZ9jQoxszc51+Y4lueYT+kCoGOzF/lXy6k= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Tycho Andersen , David Teigland , Sasha Levin , cluster-devel@redhat.com Subject: [PATCH AUTOSEL 4.14 135/150] dlm: don't leak kernel pointer to userspace Date: Sat, 16 Nov 2019 10:47:13 -0500 Message-Id: <20191116154729.9573-135-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191116154729.9573-1-sashal@kernel.org> References: <20191116154729.9573-1-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: Tycho Andersen [ Upstream commit 9de30f3f7f4d31037cfbb7c787e1089c1944b3a7 ] In copy_result_to_user(), we first create a struct dlm_lock_result, which contains a struct dlm_lksb, the last member of which is a pointer to the lvb. Unfortunately, we copy the entire struct dlm_lksb to the result struct, which is then copied to userspace at the end of the function, leaking the contents of sb_lvbptr, which is a valid kernel pointer in some cases (indeed, later in the same function the data it points to is copied to userspace). It is an error to leak kernel pointers to userspace, as it undermines KASLR protections (see e.g. 65eea8edc31 ("floppy: Do not copy a kernel pointer to user memory in FDGETPRM ioctl") for another example of this). Signed-off-by: Tycho Andersen Signed-off-by: David Teigland Signed-off-by: Sasha Levin --- fs/dlm/user.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/dlm/user.c b/fs/dlm/user.c index d18e7a539f116..1f0c071d4a861 100644 --- a/fs/dlm/user.c +++ b/fs/dlm/user.c @@ -702,7 +702,7 @@ static int copy_result_to_user(struct dlm_user_args *ua, int compat, result.version[0] = DLM_DEVICE_VERSION_MAJOR; result.version[1] = DLM_DEVICE_VERSION_MINOR; result.version[2] = DLM_DEVICE_VERSION_PATCH; - memcpy(&result.lksb, &ua->lksb, sizeof(struct dlm_lksb)); + memcpy(&result.lksb, &ua->lksb, offsetof(struct dlm_lksb, sb_lvbptr)); result.user_lksb = ua->user_lksb; /* FIXME: dlm1 provides for the user's bastparam/addr to not be updated -- 2.20.1