6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zhao Li [ Upstream commit e588e83e5c7a0f6d7a77dbbb58927c8c8cfd598e ] Tearing down an RX BA session can leave the session timer queued on a freed tid_rx. Later timer-wheel processing and the timer callback itself then run against freed memory. An RX BAR handler can dereference tid_rx under RCU before teardown unpublishes it and stay in its read-side critical section while teardown deletes the session timer. The stale handler can then rearm the timer after timer_delete_sync() returns and before the RCU callback frees tid_rx. Use timer_shutdown_sync() so rearm attempts become ineffective once teardown starts. Keep reorder_timer unchanged: teardown marks the session removed under reorder_lock and its release path checks that state before rearming. session_timer has no equivalent guard because ieee80211_rx_h_ctrl() rearms it before taking reorder_lock. Fixes: a87f736d942c ("mac80211: use RCU for RX aggregation") Cc: stable@kernel.org # 5.15+ Assisted-by: LLM sparse kasan Signed-off-by: Zhao Li Signed-off-by: Johannes Berg [ sashal: adapted the timer replacement to target del_timer_sync() instead of timer_delete_sync() ] Signed-off-by: Sasha Levin --- net/mac80211/agg-rx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/mac80211/agg-rx.c b/net/mac80211/agg-rx.c index c6fa532304500..32c1be3096b3d 100644 --- a/net/mac80211/agg-rx.c +++ b/net/mac80211/agg-rx.c @@ -103,7 +103,7 @@ void ___ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid, if (!tid_rx) return; - del_timer_sync(&tid_rx->session_timer); + timer_shutdown_sync(&tid_rx->session_timer); /* make sure ieee80211_sta_reorder_release() doesn't re-arm the timer */ spin_lock_bh(&tid_rx->reorder_lock); -- 2.53.0