cfg80211: always check for scan end on P2P device

If a P2P device wdev is removed while it has a scan, then the
scan completion might crash later as it is already freed by
that time. To avoid the crash always check the scan completion
when the P2P device is being removed for some reason. If the
driver already canceled it, don't want and free it, otherwise
warn and leak it to avoid later crashes.

In order to do this, locking needs to be changed away from the
rdev mutex (which can't always be guaranteed). For now, use
the sched_scan_mtx instead, I'll rename it to just scan_mtx in
a later patch.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/net/wireless/wext-sme.c b/net/wireless/wext-sme.c
index fb9622f6d99c..e79cb5c0655a 100644
--- a/net/wireless/wext-sme.c
+++ b/net/wireless/wext-sme.c
@@ -89,6 +89,7 @@ int cfg80211_mgd_wext_siwfreq(struct net_device *dev,
 
         cfg80211_lock_rdev(rdev);
         mutex_lock(&rdev->devlist_mtx);
+        mutex_lock(&rdev->sched_scan_mtx);
         wdev_lock(wdev);
 
         if (wdev->sme_state != CFG80211_SME_IDLE) {
@@ -135,6 +136,7 @@ int cfg80211_mgd_wext_siwfreq(struct net_device *dev,
         err = cfg80211_mgd_wext_connect(rdev, wdev);
  out:
         wdev_unlock(wdev);
+        mutex_unlock(&rdev->sched_scan_mtx);
         mutex_unlock(&rdev->devlist_mtx);
         cfg80211_unlock_rdev(rdev);
         return err;
@@ -190,6 +192,7 @@ int cfg80211_mgd_wext_siwessid(struct net_device *dev,
 
         cfg80211_lock_rdev(rdev);
         mutex_lock(&rdev->devlist_mtx);
+        mutex_lock(&rdev->sched_scan_mtx);
         wdev_lock(wdev);
 
         err = 0;
@@ -223,6 +226,7 @@ int cfg80211_mgd_wext_siwessid(struct net_device *dev,
         err = cfg80211_mgd_wext_connect(rdev, wdev);
  out:
         wdev_unlock(wdev);
+        mutex_unlock(&rdev->sched_scan_mtx);
         mutex_unlock(&rdev->devlist_mtx);
         cfg80211_unlock_rdev(rdev);
         return err;
@@ -285,6 +289,7 @@ int cfg80211_mgd_wext_siwap(struct net_device *dev,
 
         cfg80211_lock_rdev(rdev);
         mutex_lock(&rdev->devlist_mtx);
+        mutex_lock(&rdev->sched_scan_mtx);
         wdev_lock(wdev);
 
         if (wdev->sme_state != CFG80211_SME_IDLE) {
@@ -313,6 +318,7 @@ int cfg80211_mgd_wext_siwap(struct net_device *dev,
         err = cfg80211_mgd_wext_connect(rdev, wdev);
  out:
         wdev_unlock(wdev);
+        mutex_unlock(&rdev->sched_scan_mtx);
         mutex_unlock(&rdev->devlist_mtx);
         cfg80211_unlock_rdev(rdev);
         return err;