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From:   Rameshkumar Sundaram <quic_ramess@quicinc.com>
To:     <johannes@sipsolutions.net>
CC:     <linux-wireless@vger.kernel.org>,
        Rameshkumar Sundaram <quic_ramess@quicinc.com>
Subject: [PATCH] cfg80211: hold bss_lock while updating nontrans_list
Date:   Mon, 11 Apr 2022 14:37:51 +0530
Message-ID: <1649668071-9370-1-git-send-email-quic_ramess@quicinc.com>
MIME-Version: 1.0
Content-Type: text/plain
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Synchronize additions to nontrans_list of transmitting BSS with
bss_lock to avoid races. Also when cfg80211_add_nontrans_list() fails
__cfg80211_unlink_bss() needs bss_lock to be held (has lockdep assert
on bss_lock). So protect the whole block with bss_lock to avoid
races and warnings. Found during code review.

Fixes: 0b8fb8235be8 ("cfg80211: Parsing of Multiple BSSID information in scanning")
Signed-off-by: Rameshkumar Sundaram <quic_ramess@quicinc.com>
---
 net/wireless/scan.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index b888522..286cfe3 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -2011,11 +2011,13 @@ cfg80211_inform_single_bss_data(struct wiphy *wiphy,
 		/* this is a nontransmitting bss, we need to add it to
 		 * transmitting bss' list if it is not there
 		 */
+		spin_lock_bh(&rdev->bss_lock);
 		if (cfg80211_add_nontrans_list(non_tx_data->tx_bss,
 					       &res->pub)) {
 			if (__cfg80211_unlink_bss(rdev, res))
 				rdev->bss_generation++;
 		}
+		spin_unlock_bh(&rdev->bss_lock);
 	}
 
 	trace_cfg80211_return_bss(&res->pub);
-- 
2.7.4