From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753266AbeA3Wis (ORCPT ); Tue, 30 Jan 2018 17:38:48 -0500 Received: from terminus.zytor.com ([65.50.211.136]:52983 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753169AbeA3Wip (ORCPT ); Tue, 30 Jan 2018 17:38:45 -0500 Date: Tue, 30 Jan 2018 14:37:38 -0800 From: tip-bot for Dan Williams Message-ID: Cc: tglx@linutronix.de, viro@zeniv.linux.org.uk, dan.j.williams@intel.com, hpa@zytor.com, mingo@kernel.org, linux-kernel@vger.kernel.org, elena.reshetova@intel.com Reply-To: linux-kernel@vger.kernel.org, elena.reshetova@intel.com, mingo@kernel.org, hpa@zytor.com, dan.j.williams@intel.com, viro@zeniv.linux.org.uk, tglx@linutronix.de In-Reply-To: <151727418500.33451.17392199002892248656.stgit@dwillia2-desk3.amr.corp.intel.com> References: <151727418500.33451.17392199002892248656.stgit@dwillia2-desk3.amr.corp.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/pti] vfs, fdtable: Prevent bounds-check bypass via speculative execution Git-Commit-ID: 56c30ba7b348b90484969054d561f711ba196507 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 56c30ba7b348b90484969054d561f711ba196507 Gitweb: https://git.kernel.org/tip/56c30ba7b348b90484969054d561f711ba196507 Author: Dan Williams AuthorDate: Mon, 29 Jan 2018 17:03:05 -0800 Committer: Thomas Gleixner CommitDate: Tue, 30 Jan 2018 21:54:32 +0100 vfs, fdtable: Prevent bounds-check bypass via speculative execution 'fd' is a user controlled value that is used as a data dependency to read from the 'fdt->fd' array. In order to avoid potential leaks of kernel memory values, block speculative execution of the instruction stream that could issue reads based on an invalid 'file *' returned from __fcheck_files. Co-developed-by: Elena Reshetova Signed-off-by: Dan Williams Signed-off-by: Thomas Gleixner Cc: linux-arch@vger.kernel.org Cc: kernel-hardening@lists.openwall.com Cc: gregkh@linuxfoundation.org Cc: Al Viro Cc: torvalds@linux-foundation.org Cc: alan@linux.intel.com Link: https://lkml.kernel.org/r/151727418500.33451.17392199002892248656.stgit@dwillia2-desk3.amr.corp.intel.com --- include/linux/fdtable.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index 1c65817..41615f3 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -82,8 +83,10 @@ static inline struct file *__fcheck_files(struct files_struct *files, unsigned i { struct fdtable *fdt = rcu_dereference_raw(files->fdt); - if (fd < fdt->max_fds) + if (fd < fdt->max_fds) { + fd = array_index_nospec(fd, fdt->max_fds); return rcu_dereference_raw(fdt->fd[fd]); + } return NULL; }