cfg80211: hold bss_lock while updating nontrans_list

[ Upstream commit a5199b5 ]

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: 0b8fb82 ("cfg80211: Parsing of Multiple BSSID information in scanning")
Signed-off-by: Rameshkumar Sundaram <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Johannes Berg <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

Author: Rameshkumar Sundaram

net/wireless/scan.c

@@ -1978,11 +1978,13 @@ 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);