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=unavailable 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 B9861C432C3 for ; Sat, 16 Nov 2019 15:56:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 847772168B for ; Sat, 16 Nov 2019 15:56:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573919769; bh=lZr7US6FaeThTI/d26sQnxKvcAV50nPIC10UNTCyzG4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Lrdmy0h94SqMBIv/QND0YSFMom+71nUwzpv74K4sSuatfk0TuNMZi4Fye5su1cCXr JkNT5acKyxHMsDlvgSqCHN5hNkRWhmvc0Tq+YLppTdAZxpl8bdC9/Zyikmp7eZAKfs WnDMw1zR2kvH6uwAjtLbQxMgonJIHoECnWjbeDUM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731086AbfKPP4H (ORCPT ); Sat, 16 Nov 2019 10:56:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:37612 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731621AbfKPPza (ORCPT ); Sat, 16 Nov 2019 10:55:30 -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 439EA2192D; Sat, 16 Nov 2019 15:55:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573919729; bh=lZr7US6FaeThTI/d26sQnxKvcAV50nPIC10UNTCyzG4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CNBb+FUgoa7fe5aE6ksvqB+lnIdt5tC89237WDac3+/XTdhfhrcwPMSeN8pLcFADy pqJIKgIBPdzr+3jTFYAt1dYQF0Fxgo9sf52iWzZ24SaN9TLmmR/Wc48VKe1pwfRMow 8Tz+rkuiNgjvYJMZyAQjmKL31Spo5DdVciUSG3oE= 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 4.4 71/77] dlm: don't leak kernel pointer to userspace Date: Sat, 16 Nov 2019 10:53:33 -0500 Message-Id: <20191116155339.11909-71-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191116155339.11909-1-sashal@kernel.org> References: <20191116155339.11909-1-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 e40c440a45552..dd2b7416e40ae 100644 --- a/fs/dlm/user.c +++ b/fs/dlm/user.c @@ -705,7 +705,7 @@ 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