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From:   Johannes Berg <johannes@sipsolutions.net>
To:     linux-wireless@vger.kernel.org
Cc:     Johannes Berg <johannes.berg@intel.com>,
        syzbot+4305e814f9b267131776@syzkaller.appspotmail.com
Subject: [PATCH 4/4] cfg80211: call cfg80211_destroy_ifaces() with wiphy lock held
Date:   Thu, 28 Jan 2021 18:35:28 +0100
Message-Id: <20210128183454.d31df9cbd7ce.I1beb07c9492f0ade900e864a098c57041e7a7ebf@changeid>
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From: Johannes Berg <johannes.berg@intel.com>

This is needed since it calls into the driver, which must have the
same context as if we got to destroy an interface through nl80211.
Fix this, and add a direct lockdep assertion so we don't see it
pop up only when the driver calls back to cfg80211.

Fixes: a05829a7222e ("cfg80211: avoid holding the RTNL when calling the driver")
Reported-by: syzbot+4305e814f9b267131776@syzkaller.appspotmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/wireless/core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 200cd9f5fd5f..18f9a5c214b5 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -334,6 +334,7 @@ void cfg80211_destroy_ifaces(struct cfg80211_registered_device *rdev)
 	struct wireless_dev *wdev, *tmp;
 
 	ASSERT_RTNL();
+	lockdep_assert_wiphy(&rdev->wiphy);
 
 	list_for_each_entry_safe(wdev, tmp, &rdev->wiphy.wdev_list, list) {
 		if (wdev->nl_owner_dead)
@@ -349,7 +350,9 @@ static void cfg80211_destroy_iface_wk(struct work_struct *work)
 			    destroy_work);
 
 	rtnl_lock();
+	wiphy_lock(&rdev->wiphy);
 	cfg80211_destroy_ifaces(rdev);
+	wiphy_unlock(&rdev->wiphy);
 	rtnl_unlock();
 }
 
-- 
2.26.2