From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Gustavo A. R. Silva" Subject: [PATCH] atm: zatm: Fix potential Spectre v1 Date: Thu, 3 May 2018 13:17:12 -0500 Message-ID: <20180503181712.GA7443@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 gateway22.websitewelcome.com ([192.185.47.129]:22710 "EHLO gateway22.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750969AbeECSiw (ORCPT ); Thu, 3 May 2018 14:38:52 -0400 Received: from cm16.websitewelcome.com (cm16.websitewelcome.com [100.42.49.19]) by gateway22.websitewelcome.com (Postfix) with ESMTP id C38887F2E for ; Thu, 3 May 2018 13:17:14 -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:1462 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 | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/atm/zatm.c b/drivers/atm/zatm.c index 1ef67db..9c9a229 100644 --- a/drivers/atm/zatm.c +++ b/drivers/atm/zatm.c @@ -28,6 +28,7 @@ #include #include #include +#include #include "uPD98401.h" #include "uPD98402.h" @@ -1458,6 +1459,8 @@ 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); spin_lock_irqsave(&zatm_dev->lock, flags); info = zatm_dev->pool_info[pool]; if (cmd == ZATM_GETPOOLZ) { -- 2.7.4