From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Gustavo A. R. Silva" Subject: [PATCH] atm: zatm: Fix potential Spectre v1 Date: Fri, 29 Jun 2018 13:28:07 -0500 Message-ID: <20180629182807.GA26287@embeddedor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-atm-general@lists.sourceforge.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" To: Chas Williams <3chas3@gmail.com>, "David S. Miller" Return-path: Received: from gateway33.websitewelcome.com ([192.185.146.80]:22468 "EHLO gateway33.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753796AbeF2S2K (ORCPT ); Fri, 29 Jun 2018 14:28:10 -0400 Received: from cm11.websitewelcome.com (cm11.websitewelcome.com [100.42.49.5]) by gateway33.websitewelcome.com (Postfix) with ESMTP id 570B85CCB10 for ; Fri, 29 Jun 2018 13:28:09 -0500 (CDT) Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: pool can be indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: drivers/atm/zatm.c:1491 zatm_ioctl() warn: potential spectre issue 'zatm_dev->pool_info' (local cap) Fix this by sanitizing pool before using it to index zatm_dev->pool_info Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva --- drivers/atm/zatm.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/atm/zatm.c b/drivers/atm/zatm.c index a8d2eb0..2c288d1 100644 --- a/drivers/atm/zatm.c +++ b/drivers/atm/zatm.c @@ -1483,6 +1483,8 @@ static int zatm_ioctl(struct atm_dev *dev,unsigned int cmd,void __user *arg) return -EFAULT; if (pool < 0 || pool > ZATM_LAST_POOL) return -EINVAL; + pool = array_index_nospec(pool, + ZATM_LAST_POOL + 1); if (copy_from_user(&info, &((struct zatm_pool_req __user *) arg)->info, sizeof(info))) return -EFAULT; -- 2.7.4