diff options
| author | Johannes Berg <johannes.berg@intel.com> | 2023-08-16 15:38:04 +0200 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2023-09-11 16:43:35 +0200 |
| commit | 37c20b2effe987b806c8de6d12978e4ffeff026f (patch) | |
| tree | 128edc5ab795b720f25e34399b5c5415d98360b8 /net/wireless/core.c | |
| parent | 8ba438ef3cacc4808a63ed0ce24d4f0942cfe55d (diff) | |
| download | lwn-37c20b2effe987b806c8de6d12978e4ffeff026f.tar.gz lwn-37c20b2effe987b806c8de6d12978e4ffeff026f.zip | |
wifi: cfg80211: fix cqm_config access race
Max Schulze reports crashes with brcmfmac. The reason seems
to be a race between userspace removing the CQM config and
the driver calling cfg80211_cqm_rssi_notify(), where if the
data is freed while cfg80211_cqm_rssi_notify() runs it will
crash since it assumes wdev->cqm_config is set. This can't
be fixed with a simple non-NULL check since there's nothing
we can do for locking easily, so use RCU instead to protect
the pointer, but that requires pulling the updates out into
an asynchronous worker so they can sleep and call back into
the driver.
Since we need to change the free anyway, also change it to
go back to the old settings if changing the settings fails.
Reported-and-tested-by: Max Schulze <max.schulze@online.de>
Closes: https://lore.kernel.org/r/ac96309a-8d8d-4435-36e6-6d152eb31876@online.de
Fixes: 4a4b8169501b ("cfg80211: Accept multiple RSSI thresholds for CQM")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'net/wireless/core.c')
| -rw-r--r-- | net/wireless/core.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/net/wireless/core.c b/net/wireless/core.c index 25bc2e50a061..64e861617110 100644 --- a/net/wireless/core.c +++ b/net/wireless/core.c @@ -1181,16 +1181,11 @@ void wiphy_rfkill_set_hw_state_reason(struct wiphy *wiphy, bool blocked, } EXPORT_SYMBOL(wiphy_rfkill_set_hw_state_reason); -void cfg80211_cqm_config_free(struct wireless_dev *wdev) -{ - kfree(wdev->cqm_config); - wdev->cqm_config = NULL; -} - static void _cfg80211_unregister_wdev(struct wireless_dev *wdev, bool unregister_netdev) { struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy); + struct cfg80211_cqm_config *cqm_config; unsigned int link_id; ASSERT_RTNL(); @@ -1227,7 +1222,10 @@ static void _cfg80211_unregister_wdev(struct wireless_dev *wdev, kfree_sensitive(wdev->wext.keys); wdev->wext.keys = NULL; #endif - cfg80211_cqm_config_free(wdev); + wiphy_work_cancel(wdev->wiphy, &wdev->cqm_rssi_work); + /* deleted from the list, so can't be found from nl80211 any more */ + cqm_config = rcu_access_pointer(wdev->cqm_config); + kfree_rcu(cqm_config, rcu_head); /* * Ensure that all events have been processed and @@ -1379,6 +1377,8 @@ void cfg80211_init_wdev(struct wireless_dev *wdev) wdev->wext.connect.auth_type = NL80211_AUTHTYPE_AUTOMATIC; #endif + wiphy_work_init(&wdev->cqm_rssi_work, cfg80211_cqm_rssi_notify_work); + if (wdev->wiphy->flags & WIPHY_FLAG_PS_ON_BY_DEFAULT) wdev->ps = true; else |