From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=0.4 required=3.0 tests=BIGNUM_EMAILS,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0A7AC43331 for ; Sat, 7 Sep 2019 13:04:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 715E321835 for ; Sat, 7 Sep 2019 13:04:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="JzG0ZR/v" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405962AbfIGNEo (ORCPT ); Sat, 7 Sep 2019 09:04:44 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:36978 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732838AbfIGNEo (ORCPT ); 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Sat, 7 Sep 2019 13:02:40 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 2uv3wj99y4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 07 Sep 2019 13:02:40 +0000 Received: from abhmp0017.oracle.com (abhmp0017.oracle.com [141.146.116.23]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x87D2eBg031247; Sat, 7 Sep 2019 13:02:40 GMT Received: from mwanda (/41.57.98.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sat, 07 Sep 2019 06:02:39 -0700 Date: Sat, 7 Sep 2019 16:02:34 +0300 From: Dan Carpenter To: masashi.honma@gmail.com Cc: linux-wireless@vger.kernel.org Subject: [bug report] nl80211: Fix possible Spectre-v1 for CQM RSSI thresholds Message-ID: <20190907130234.GA32057@mwanda> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9372 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=793 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1909070140 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9372 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=857 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1909070141 Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Hello Masashi Honma, The patch 1222a1601488: "nl80211: Fix possible Spectre-v1 for CQM RSSI thresholds" from Sep 25, 2018, leads to the following static checker warning: net/wireless/nl80211.c:10820 cfg80211_cqm_rssi_update() warn: disabling speculation after use: 'i' net/wireless/nl80211.c 10804 last = wdev->cqm_config->last_rssi_event_value; 10805 hyst = wdev->cqm_config->rssi_hyst; 10806 n = wdev->cqm_config->n_rssi_thresholds; 10807 10808 for (i = 0; i < n; i++) 10809 if (last < wdev->cqm_config->rssi_thresholds[i]) ^^^^^^^^^^^^^^^^^^ We've already used "i" as an index. 10810 break; 10811 10812 low_index = i - 1; 10813 if (low_index >= 0) { 10814 low_index = array_index_nospec(low_index, n); ^^^^^^^^^^^^^^^^^^ 10815 low = wdev->cqm_config->rssi_thresholds[low_index] - hyst; 10816 } else { 10817 low = S32_MIN; 10818 } 10819 if (i < n) { 10820 i = array_index_nospec(i, n); ^^^^^^^^^^^^^^^^^^ So this seems like closing the barn door after the horses have left. 10821 high = wdev->cqm_config->rssi_thresholds[i] + hyst - 1; 10822 } else { 10823 high = S32_MAX; 10824 } regards, dan carpenter