From 73350424bec9c76cf42d4d502ff156c7d5daf191 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 6 Feb 2019 08:03:10 +0200 Subject: [PATCH] cfg80211: pmsr: fix abort locking When we destroy the interface we already hold the wdev->mtx while calling cfg80211_pmsr_wdev_down(), which assumes this isn't true and flushes the worker that takes the lock, thus leading to a deadlock. Fix this by refactoring the worker and calling its code in cfg80211_pmsr_wdev_down() directly. We still need to flush the work later to make sure it's not still running and will crash, but it will not do anything. Fixes: 9bb7e0f24e7e ("cfg80211: add peer measurement with FTM initiator API") Signed-off-by: Johannes Berg --- net/wireless/core.c | 2 ++ net/wireless/pmsr.c | 22 +++++++++++++++------- 2 files changed, 17 insertions(+), 7 deletions(-) diff --git a/net/wireless/core.c b/net/wireless/core.c index 623dfe5e211c..b36ad8efb5e5 100644 --- a/net/wireless/core.c +++ b/net/wireless/core.c @@ -1068,6 +1068,8 @@ static void __cfg80211_unregister_wdev(struct wireless_dev *wdev, bool sync) ASSERT_RTNL(); + flush_work(&wdev->pmsr_free_wk); + nl80211_notify_iface(rdev, wdev, NL80211_CMD_DEL_INTERFACE); list_del_rcu(&wdev->list); diff --git a/net/wireless/pmsr.c b/net/wireless/pmsr.c index f2e388e329fd..78c3f5633692 100644 --- a/net/wireless/pmsr.c +++ b/net/wireless/pmsr.c @@ -529,14 +529,14 @@ free: } EXPORT_SYMBOL_GPL(cfg80211_pmsr_report); -void cfg80211_pmsr_free_wk(struct work_struct *work) +static void cfg80211_pmsr_process_abort(struct wireless_dev *wdev) { - struct wireless_dev *wdev = container_of(work, struct wireless_dev, - pmsr_free_wk); struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy); struct cfg80211_pmsr_request *req, *tmp; LIST_HEAD(free_list); + lockdep_assert_held(&wdev->mtx); + spin_lock_bh(&wdev->pmsr_lock); list_for_each_entry_safe(req, tmp, &wdev->pmsr_list, list) { if (req->nl_portid) @@ -546,14 +546,22 @@ void cfg80211_pmsr_free_wk(struct work_struct *work) spin_unlock_bh(&wdev->pmsr_lock); list_for_each_entry_safe(req, tmp, &free_list, list) { - wdev_lock(wdev); rdev_abort_pmsr(rdev, wdev, req); - wdev_unlock(wdev); kfree(req); } } +void cfg80211_pmsr_free_wk(struct work_struct *work) +{ + struct wireless_dev *wdev = container_of(work, struct wireless_dev, + pmsr_free_wk); + + wdev_lock(wdev); + cfg80211_pmsr_process_abort(wdev); + wdev_unlock(wdev); +} + void cfg80211_pmsr_wdev_down(struct wireless_dev *wdev) { struct cfg80211_pmsr_request *req; @@ -567,8 +575,8 @@ void cfg80211_pmsr_wdev_down(struct wireless_dev *wdev) spin_unlock_bh(&wdev->pmsr_lock); if (found) - schedule_work(&wdev->pmsr_free_wk); - flush_work(&wdev->pmsr_free_wk); + cfg80211_pmsr_process_abort(wdev); + WARN_ON(!list_empty(&wdev->pmsr_list)); } -- 2.30.2