4.4-stable review patch.  If anyone has any objections, please let me know.


From: Dan Williams <dan.j.willi...@intel.com>

(cherry picked from commit 259d8c1e984318497c84eef547bbb6b1d9f4eb05)

Wireless drivers rely on parse_txq_params to validate that txq_params->ac
is less than NL80211_NUM_ACS by the time the low-level driver's ->conf_tx()
handler is called. Use a new helper, array_index_nospec(), to sanitize
txq_params->ac with respect to speculation. I.e. ensure that any
speculation into ->conf_tx() handlers is done with a value of
txq_params->ac that is within the bounds of [0, NL80211_NUM_ACS).

Reported-by: Christian Lamparter <chunk...@gmail.com>
Reported-by: Elena Reshetova <elena.reshet...@intel.com>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Acked-by: Johannes Berg <johan...@sipsolutions.net>
Cc: linux-a...@vger.kernel.org
Cc: kernel-harden...@lists.openwall.com
Cc: gre...@linuxfoundation.org
Cc: linux-wirel...@vger.kernel.org
Cc: torva...@linux-foundation.org
Cc: "David S. Miller" <da...@davemloft.net>
Cc: a...@linux.intel.com
Signed-off-by: David Woodhouse <d...@amazon.co.uk>
[jwang: cherry pick to 4.4]
Signed-off-by: Jack Wang <jinpu.w...@profitbricks.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
 net/wireless/nl80211.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -16,6 +16,7 @@
 #include <linux/nl80211.h>
 #include <linux/rtnetlink.h>
 #include <linux/netlink.h>
+#include <linux/nospec.h>
 #include <linux/etherdevice.h>
 #include <net/net_namespace.h>
 #include <net/genetlink.h>
@@ -1879,20 +1880,22 @@ static const struct nla_policy txq_param
 static int parse_txq_params(struct nlattr *tb[],
                            struct ieee80211_txq_params *txq_params)
+       u8 ac;
        if (!tb[NL80211_TXQ_ATTR_AC] || !tb[NL80211_TXQ_ATTR_TXOP] ||
            !tb[NL80211_TXQ_ATTR_CWMIN] || !tb[NL80211_TXQ_ATTR_CWMAX] ||
                return -EINVAL;
-       txq_params->ac = nla_get_u8(tb[NL80211_TXQ_ATTR_AC]);
+       ac = nla_get_u8(tb[NL80211_TXQ_ATTR_AC]);
        txq_params->txop = nla_get_u16(tb[NL80211_TXQ_ATTR_TXOP]);
        txq_params->cwmin = nla_get_u16(tb[NL80211_TXQ_ATTR_CWMIN]);
        txq_params->cwmax = nla_get_u16(tb[NL80211_TXQ_ATTR_CWMAX]);
        txq_params->aifs = nla_get_u8(tb[NL80211_TXQ_ATTR_AIFS]);
-       if (txq_params->ac >= NL80211_NUM_ACS)
+       if (ac >= NL80211_NUM_ACS)
                return -EINVAL;
+       txq_params->ac = array_index_nospec(ac, NL80211_NUM_ACS);
        return 0;

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