6.6-stable review patch. If anyone has any objections, please let me know.
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From: "L�o Lam" leo@leolam.fr
Commit 008afb9f3d57 ("wifi: cfg80211: fix CQM for non-range use" backported to 6.6.x) causes nl80211_set_cqm_rssi not to release the wdev lock in some of the error paths.
Of course, the ensuing deadlock causes userland network managers to break pretty badly, and on typical systems this also causes lockups on on suspend, poweroff and reboot. See [1], [2], [3] for example reports.
The upstream commit 7e7efdda6adb ("wifi: cfg80211: fix CQM for non-range use"), committed in November 2023, is completely fine because there was another commit in August 2023 that removed the wdev lock: see commit 076fc8775daf ("wifi: cfg80211: remove wdev mutex").
The reason things broke in 6.6.5 is that commit 4338058f6009 was applied without also applying 076fc8775daf.
Commit 076fc8775daf ("wifi: cfg80211: remove wdev mutex") is a rather large commit; adjusting the error handling (which is what this commit does) yields a much simpler patch and was tested to work properly.
Fix the deadlock by releasing the lock before returning.
[1] https://bugzilla.kernel.org/show_bug.cgi?id=218247 [2] https://bbs.archlinux.org/viewtopic.php?id=290976 [3] https://lore.kernel.org/all/87sf4belmm.fsf@turtle.gmx.de/
Link: https://lore.kernel.org/stable/e374bb16-5b13-44cc-b11a-2f4eefb1ecf5@manjaro.... Fixes: 008afb9f3d57 ("wifi: cfg80211: fix CQM for non-range use") Tested-by: "L�o Lam" leo@leolam.fr Tested-by: Philip Müller philm@manjaro.org Cc: stable@vger.kernel.org Cc: Johannes Berg johannes.berg@intel.com Signed-off-by: "L�o Lam" leo@leolam.fr Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/wireless/nl80211.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)
--- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -12906,17 +12906,23 @@ static int nl80211_set_cqm_rssi(struct g lockdep_is_held(&wdev->mtx));
/* if already disabled just succeed */ - if (!n_thresholds && !old) - return 0; + if (!n_thresholds && !old) { + err = 0; + goto unlock; + }
if (n_thresholds > 1) { if (!wiphy_ext_feature_isset(&rdev->wiphy, NL80211_EXT_FEATURE_CQM_RSSI_LIST) || - !rdev->ops->set_cqm_rssi_range_config) - return -EOPNOTSUPP; + !rdev->ops->set_cqm_rssi_range_config) { + err = -EOPNOTSUPP; + goto unlock; + } } else { - if (!rdev->ops->set_cqm_rssi_config) - return -EOPNOTSUPP; + if (!rdev->ops->set_cqm_rssi_config) { + err = -EOPNOTSUPP; + goto unlock; + } }
if (n_thresholds) {