From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935615AbbGHP4f (ORCPT ); Wed, 8 Jul 2015 11:56:35 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:47818 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758841AbbGHPk4 (ORCPT ); Wed, 8 Jul 2015 11:40:56 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Sasha Levin , Al Viro , Linus Torvalds , Moritz Muehlenhoff , Kamal Mostafa Subject: [PATCH 3.13.y-ckt 03/56] vfs: read file_handle only once in handle_to_path Date: Wed, 8 Jul 2015 08:39:44 -0700 Message-Id: <1436370037-25874-4-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1436370037-25874-1-git-send-email-kamal@canonical.com> References: <1436370037-25874-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11-ckt23 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Sasha Levin commit 161f873b89136eb1e69477c847d5a5033239d9ba upstream. We used to read file_handle twice. Once to get the amount of extra bytes, and once to fetch the entire structure. This may be problematic since we do size verifications only after the first read, so if the number of extra bytes changes in userspace between the first and second calls, we'll have an incoherent view of file_handle. Instead, read the constant size once, and copy that over to the final structure without having to re-read it again. Signed-off-by: Sasha Levin Cc: Al Viro Signed-off-by: Linus Torvalds Reference: CVE-2015-1420 Cc: Moritz Muehlenhoff Signed-off-by: Kamal Mostafa --- fs/fhandle.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/fhandle.c b/fs/fhandle.c index 999ff5c..d59712d 100644 --- a/fs/fhandle.c +++ b/fs/fhandle.c @@ -195,8 +195,9 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh, goto out_err; } /* copy the full handle */ - if (copy_from_user(handle, ufh, - sizeof(struct file_handle) + + *handle = f_handle; + if (copy_from_user(&handle->f_handle, + &ufh->f_handle, f_handle.handle_bytes)) { retval = -EFAULT; goto out_handle; -- 1.9.1