From a2083eeb119fb9307258baea9b7c243ca9a2e0b6 Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg@intel.com>
Date: Thu, 30 Sep 2021 13:11:21 +0200
Subject: [PATCH] cfg80211: scan: fix RCU in cfg80211_add_nontrans_list()
Git-commit: a2083eeb119fb9307258baea9b7c243ca9a2e0b6
Patch-mainline: v5.15
References: git-fixes stable-5.14.16

The SSID pointer is pointing to RCU protected data, so we
need to have it under rcu_read_lock() for the entire use.
Fix this.

Cc: stable@vger.kernel.org
Fixes: 0b8fb8235be8 ("cfg80211: Parsing of Multiple BSSID information in scanning")
Link: https://lore.kernel.org/r/20210930131120.6ddfc603aa1d.I2137344c4e2426525b1a8e4ce5fca82f8ecbfe7e@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/wireless/scan.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 11c68b159324..adc0d14cfd86 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -418,14 +418,17 @@ cfg80211_add_nontrans_list(struct cfg80211_bss *trans_bss,
 	}
 	ssid_len = ssid[1];
 	ssid = ssid + 2;
-	rcu_read_unlock();
 
 	/* check if nontrans_bss is in the list */
 	list_for_each_entry(bss, &trans_bss->nontrans_list, nontrans_list) {
-		if (is_bss(bss, nontrans_bss->bssid, ssid, ssid_len))
+		if (is_bss(bss, nontrans_bss->bssid, ssid, ssid_len)) {
+			rcu_read_unlock();
 			return 0;
+		}
 	}
 
+	rcu_read_unlock();
+
 	/* add to the list */
 	list_add_tail(&nontrans_bss->nontrans_list, &trans_bss->nontrans_list);
 	return 0;
-- 
2.26.2