linux-kernel - [PATCH 5.15 101/128] mac80211: fix locking in ieee80211_start

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Message-Id: <20211227151334.891900787@linuxfoundation.org>
Date:   Mon, 27 Dec 2021 16:31:16 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Johannes Berg <johannes.berg@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        syzbot+11c342e5e30e9539cabd@...kaller.appspotmail.com
Subject: [PATCH 5.15 101/128] mac80211: fix locking in ieee80211_start_ap error path

From: Johannes Berg <johannes.berg@...el.com>

commit 87a270625a89fc841f1a7e21aae6176543d8385c upstream.

We need to hold the local->mtx to release the channel context,
as even encoded by the lockdep_assert_held() there. Fix it.

Cc: stable@...r.kernel.org
Fixes: 295b02c4be74 ("mac80211: Add FILS discovery support")
Reported-and-tested-by: syzbot+11c342e5e30e9539cabd@...kaller.appspotmail.com
Link: https://lore.kernel.org/r/20211220090836.cee3d59a1915.I36bba9b79dc2ff4d57c3c7aa30dff9a003fe8c5c@changeid
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/mac80211/cfg.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1226,7 +1226,10 @@ static int ieee80211_start_ap(struct wip
 	return 0;
 
 error:
+	mutex_lock(&local->mtx);
 	ieee80211_vif_release_channel(sdata);
+	mutex_unlock(&local->mtx);
+
 	return err;
 }