6.1-stable review patch. If anyone has any objections, please let me know.
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From: Johannes Berg johannes.berg@intel.com
[ Upstream commit 05f136220d17839eb7c155f015ace9152f603225 ]
As previously reported by Alexander, whose commit 69403bad97aa ("wifi: mac80211: sdata can be NULL during AMPDU start") I'm reverting as part of this commit, there's a race between station destruction and aggregation setup, where the aggregation setup can happen while the station is being removed and queue the work after ieee80211_sta_tear_down_BA_sessions() has already run in __sta_info_destroy_part1(), and thus the worker will run with a now freed station. In his case, this manifested in a NULL sdata pointer, but really there's no guarantee whatsoever.
The real issue seems to be that it's possible at all to have a situation where this occurs - we want to stop the BA sessions when doing _part1, but we cannot be sure, and WLAN_STA_BLOCK_BA isn't necessarily effective since we don't know that the setup isn't concurrently running and already got past the check.
Simply call ieee80211_sta_tear_down_BA_sessions() again in the second part of station destruction, since at that point really nothing else can hold a reference to the station any more.
Also revert the sdata checks since those are just misleading at this point.
Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/mac80211/agg-tx.c | 6 +----- net/mac80211/driver-ops.c | 3 --- net/mac80211/sta_info.c | 14 ++++++++++++++ 3 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c index 85d2b9e4b51ce..e26a72f3a1042 100644 --- a/net/mac80211/agg-tx.c +++ b/net/mac80211/agg-tx.c @@ -491,7 +491,7 @@ void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid) { struct tid_ampdu_tx *tid_tx; struct ieee80211_local *local = sta->local; - struct ieee80211_sub_if_data *sdata; + struct ieee80211_sub_if_data *sdata = sta->sdata; struct ieee80211_ampdu_params params = { .sta = &sta->sta, .action = IEEE80211_AMPDU_TX_START, @@ -519,7 +519,6 @@ void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid) */ synchronize_net();
- sdata = sta->sdata; params.ssn = sta->tid_seq[tid] >> 4; ret = drv_ampdu_action(local, sdata, ¶ms); tid_tx->ssn = params.ssn; @@ -533,9 +532,6 @@ void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid) */ set_bit(HT_AGG_STATE_DRV_READY, &tid_tx->state); } else if (ret) { - if (!sdata) - return; - ht_dbg(sdata, "BA request denied - HW unavailable for %pM tid %d\n", sta->sta.addr, tid); diff --git a/net/mac80211/driver-ops.c b/net/mac80211/driver-ops.c index c08d3c9a4a177..5392ffa182704 100644 --- a/net/mac80211/driver-ops.c +++ b/net/mac80211/driver-ops.c @@ -391,9 +391,6 @@ int drv_ampdu_action(struct ieee80211_local *local,
might_sleep();
- if (!sdata) - return -EIO; - sdata = get_bss_sdata(sdata); if (!check_sdata_in_driver(sdata)) return -EIO; diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c index 91768abf2d75b..dd1864f6549f2 100644 --- a/net/mac80211/sta_info.c +++ b/net/mac80211/sta_info.c @@ -1272,6 +1272,20 @@ static void __sta_info_destroy_part2(struct sta_info *sta) * after _part1 and before _part2! */
+ /* + * There's a potential race in _part1 where we set WLAN_STA_BLOCK_BA + * but someone might have just gotten past a check, and not yet into + * queuing the work/creating the data/etc. + * + * Do another round of destruction so that the worker is certainly + * canceled before we later free the station. + * + * Since this is after synchronize_rcu()/synchronize_net() we're now + * certain that nobody can actually hold a reference to the STA and + * be calling e.g. ieee80211_start_tx_ba_session(). + */ + ieee80211_sta_tear_down_BA_sessions(sta, AGG_STOP_DESTROY_STA); + might_sleep(); lockdep_assert_held(&local->sta_mtx);