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

Dan Williams
2018-01-06T01:18:56Z

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@googlemail.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.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;