[tip:x86/pti] nl80211: Sanitize array index in parse_txq_params

From: tip-bot for Dan Williams
Date: Tue Jan 30 2018 - 17:41:22 EST


Commit-ID: 259d8c1e984318497c84eef547bbb6b1d9f4eb05
Gitweb: https://git.kernel.org/tip/259d8c1e984318497c84eef547bbb6b1d9f4eb05
Author: Dan Williams <dan.j.williams@xxxxxxxxx>
AuthorDate: Mon, 29 Jan 2018 17:03:15 -0800
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Tue, 30 Jan 2018 21:54:32 +0100

nl80211: Sanitize array index in parse_txq_params

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 <chunkeey@xxxxxxxxx>
Reported-by: Elena Reshetova <elena.reshetova@xxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: kernel-hardening@xxxxxxxxxxxxxxxxxx
Cc: gregkh@xxxxxxxxxxxxxxxxxxx
Cc: linux-wireless@xxxxxxxxxxxxxxx
Cc: torvalds@xxxxxxxxxxxxxxxxxxxx
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: alan@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/151727419584.33451.7700736761686184303.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

---
net/wireless/nl80211.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 542a4fc..4bbcfc1 100644
--- 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>
@@ -2056,20 +2057,22 @@ static const struct nla_policy txq_params_policy[NL80211_TXQ_ATTR_MAX + 1] = {
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] ||
!tb[NL80211_TXQ_ATTR_AIFS])
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;
}