netdev - [PATCH 08/18] carl9170: prevent bounds-check bypass via speculative execution

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Message-ID: <151520103755.32271.6819511294540882298.stgit@dwillia2-desk3.amr.corp.intel.com>
Date:   Fri, 05 Jan 2018 17:10:37 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-arch@...r.kernel.org, peterz@...radead.org,
        netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
        Elena Reshetova <elena.reshetova@...el.com>,
        gregkh@...uxfoundation.org,
        Christian Lamparter <chunkeey@...glemail.com>,
        tglx@...utronix.de, torvalds@...ux-foundation.org,
        Kalle Valo <kvalo@...eaurora.org>, alan@...ux.intel.com
Subject: [PATCH 08/18] carl9170: prevent bounds-check bypass via speculative
 execution

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 <chunkeey@...glemail.com>
Cc: Kalle Valo <kvalo@...eaurora.org>
Cc: linux-wireless@...r.kernel.org
Cc: netdev@...r.kernel.org
Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 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 <linux/module.h>
 #include <linux/etherdevice.h>
 #include <linux/random.h>
+#include <linux/compiler.h>
 #include <net/mac80211.h>
 #include <net/cfg80211.h>
 #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;