From: Masashi Honma <masashi.honma@gmail.com>
Date: Sun, 8 Sep 2019 09:56:53 +0900
Subject: nl80211: Fix possible Spectre-v1 for CQM RSSI thresholds
Git-commit: 4b2c5a14cd8005a900075f7dfec87473c6ee66fb
Patch-mainline: 5.4-rc1
References: bnc#1151927 5.3.1

commit 1222a1601488 ("nl80211: Fix possible Spectre-v1 for CQM
RSSI thresholds") was incomplete and requires one more fix to
prevent accessing to rssi_thresholds[n] because user can control
rssi_thresholds[i] values to make i reach to n. For example,
rssi_thresholds = {-400, -300, -200, -100} when last is -34.

Cc: stable@vger.kernel.org
Fixes: 1222a1601488 ("nl80211: Fix possible Spectre-v1 for CQM RSSI thresholds")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Masashi Honma <masashi.honma@gmail.com>
Link: https://lore.kernel.org/r/20190908005653.17433-1-masashi.honma@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/wireless/nl80211.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -10659,9 +10659,11 @@ static int cfg80211_cqm_rssi_update(stru
 	hyst = wdev->cqm_config->rssi_hyst;
 	n = wdev->cqm_config->n_rssi_thresholds;
 
-	for (i = 0; i < n; i++)
+	for (i = 0; i < n; i++) {
+		i = array_index_nospec(i, n);
 		if (last < wdev->cqm_config->rssi_thresholds[i])
 			break;
+	}
 
 	low_index = i - 1;
 	if (low_index >= 0) {