From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932328AbcHHT2F (ORCPT ); Mon, 8 Aug 2016 15:28:05 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36672 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932454AbcHHTTl (ORCPT ); Mon, 8 Aug 2016 15:19:41 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pengfei Wang , Dan Carpenter , Kees Cook , Gwendal Grignou , Olof Johansson Subject: [PATCH 4.6 66/96] platform/chrome: cros_ec_dev - double fetch bug in ioctl Date: Mon, 8 Aug 2016 21:11:29 +0200 Message-Id: <20160808180246.776341753@linuxfoundation.org> X-Mailer: git-send-email 2.9.2 In-Reply-To: <20160808180243.898163389@linuxfoundation.org> References: <20160808180243.898163389@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Carpenter commit 096cdc6f52225835ff503f987a0d68ef770bb78e upstream. We verify "u_cmd.outsize" and "u_cmd.insize" but we need to make sure that those values have not changed between the two copy_from_user() calls. Otherwise it could lead to a buffer overflow. Additionally, cros_ec_cmd_xfer() can set s_cmd->insize to a lower value. We should use the new smaller value so we don't copy too much data to the user. Reported-by: Pengfei Wang Fixes: a841178445bb ('mfd: cros_ec: Use a zero-length array for command data') Signed-off-by: Dan Carpenter Reviewed-by: Kees Cook Tested-by: Gwendal Grignou Signed-off-by: Olof Johansson Signed-off-by: Greg Kroah-Hartman --- drivers/platform/chrome/cros_ec_dev.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/drivers/platform/chrome/cros_ec_dev.c +++ b/drivers/platform/chrome/cros_ec_dev.c @@ -147,13 +147,19 @@ static long ec_device_ioctl_xcmd(struct goto exit; } + if (u_cmd.outsize != s_cmd->outsize || + u_cmd.insize != s_cmd->insize) { + ret = -EINVAL; + goto exit; + } + s_cmd->command += ec->cmd_offset; ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd); /* Only copy data to userland if data was received. */ if (ret < 0) goto exit; - if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + u_cmd.insize)) + if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + s_cmd->insize)) ret = -EFAULT; exit: kfree(s_cmd);