Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753415AbeAFOXs (ORCPT + 1 other); Sat, 6 Jan 2018 09:23:48 -0500 Received: from mail-wr0-f196.google.com ([209.85.128.196]:39038 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753215AbeAFOXo (ORCPT ); Sat, 6 Jan 2018 09:23:44 -0500 X-Google-Smtp-Source: ACJfBotUT4o/L5pXC+48gKiGQomVPBHkikRaur9PuKkfcDkr0lJ1OqM81svPhnOEKRJvZqdmXwLfaA== From: Christian Lamparter X-Google-Original-From: Christian Lamparter To: Dan Williams Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, peterz@infradead.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, Elena Reshetova , gregkh@linuxfoundation.org, tglx@linutronix.de, torvalds@linux-foundation.org, Kalle Valo , alan@linux.intel.com Subject: Re: [PATCH 08/18] carl9170: prevent bounds-check bypass via speculative execution Date: Sat, 06 Jan 2018 15:23:40 +0100 Message-ID: <3586343.KJymplWpZW@debian64> In-Reply-To: <151520103755.32271.6819511294540882298.stgit@dwillia2-desk3.amr.corp.intel.com> References: <151520099201.32271.4677179499894422956.stgit@dwillia2-desk3.amr.corp.intel.com> <151520103755.32271.6819511294540882298.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Saturday, January 6, 2018 2:10:37 AM CET Dan Williams wrote: > Static analysis reports that 'queue' may be a user controlled value that > is used as a data dependency to read from the 'ar9170_qmap' 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 result of 'ar9170_qmap[queue]'. In this case the > value of 'ar9170_qmap[queue]' is immediately reused as an index to the > 'ar->edcf' array. > > Based on an original patch by Elena Reshetova. > > Cc: Christian Lamparter > Cc: Kalle Valo > Cc: linux-wireless@vger.kernel.org > Cc: netdev@vger.kernel.org > Signed-off-by: Elena Reshetova > Signed-off-by: Dan Williams > --- > drivers/net/wireless/ath/carl9170/main.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/wireless/ath/carl9170/main.c b/drivers/net/wireless/ath/carl9170/main.c > index 988c8857d78c..0ff34cbe2b62 100644 > --- a/drivers/net/wireless/ath/carl9170/main.c > +++ b/drivers/net/wireless/ath/carl9170/main.c > @@ -41,6 +41,7 @@ > #include > #include > #include > +#include > #include > #include > #include "hw.h" > @@ -1384,11 +1385,12 @@ static int carl9170_op_conf_tx(struct ieee80211_hw *hw, > const struct ieee80211_tx_queue_params *param) > { > struct ar9170 *ar = hw->priv; > + const u8 *elem; > int ret; > > mutex_lock(&ar->mutex); > - if (queue < ar->hw->queues) { > - memcpy(&ar->edcf[ar9170_qmap[queue]], param, sizeof(*param)); > + if ((elem = nospec_array_ptr(ar9170_qmap, queue, ar->hw->queues))) { > + memcpy(&ar->edcf[*elem], param, sizeof(*param)); > ret = carl9170_set_qos(ar); > } else { > ret = -EINVAL; > > About the "queue" in carl9170_op_conf_tx, p54_conf_tx and cw1200_conf_tx: The only way a user can set this in any meaningful way would be via a NL80211_CMD_SET_WIPHY netlink message. However, the value will get vetted there by cfg80211's parse_txq_params [0]. This is long before it reaches any of the *_op_conf_tx functions. And Furthermore a invalid queue (param->ac) would cause a crash in this line in mac80211 before it even reaches the driver [1]: | sdata->tx_conf[params->ac] = p; | ^^^^^^^^ | if (drv_conf_tx(local, sdata, >>>> params->ac <<<<, &p)) { | ^^ (this is a wrapper for the *_op_conf_tx) I don't think these chin-up exercises are needed. [0] [1]