diff options
| author | Cen Zhang <zzzccc427@gmail.com> | 2026-07-06 22:08:41 +0800 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2026-07-07 09:23:23 +0200 |
| commit | f3858d5b1432098c1936e03d6e03dd0e33facf60 (patch) | |
| tree | fd8cdd766405aad89d9e26784ac8de863176c87e | |
| parent | 4a360c6e18dfa9d70006c7247a6a8cc8dfe0d60f (diff) | |
wifi: mac80211: free AP_VLAN bc_buf SKBs outside IRQ lock
ieee80211_do_stop() removes AP_VLAN packets from the parent AP
ps->bc_buf while holding ps->bc_buf.lock with IRQs disabled. It then
calls ieee80211_free_txskb() before dropping the lock.
ieee80211_free_txskb() is not just a passive SKB release. For SKBs with
TX status state it can report a dropped frame through cfg80211/nl80211,
and that path can reach netlink tap transmit. This is the same reason
the pending queue cleanup in ieee80211_do_stop() already unlinks SKBs
under the queue lock and frees them after IRQ state is restored.
The buggy scenario involves two paths, with each column showing the
order within that path:
AP_VLAN management TX: AP_VLAN stop:
1. attach ACK-status state 1. clear the running state
2. queue a multicast SKB on 2. take ps->bc_buf.lock with IRQs
parent ps->bc_buf disabled
3. unlink the AP_VLAN SKB
4. call ieee80211_free_txskb()
Unlink matching AP_VLAN SKBs from ps->bc_buf under the existing lock,
but move them to a local free queue. Drop the lock and restore IRQ state
before calling ieee80211_free_txskb().
WARNING: kernel/softirq.c:430 at __local_bh_enable_ip
Fixes: 397a7a24ef8c ("mac80211: free ps->bc_buf skbs on vlan device stop")
Assisted-by: Codex:gpt-5.5
Signed-off-by: Cen Zhang <zzzccc427@gmail.com>
Link: https://patch.msgid.link/20260706140841.581566-1-zzzccc427@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
| -rw-r--r-- | net/mac80211/iface.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c index 086272c3ec08..43460a705a6b 100644 --- a/net/mac80211/iface.c +++ b/net/mac80211/iface.c @@ -588,6 +588,7 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, bool going_do WARN_ON(!list_empty(&sdata->u.ap.vlans)); } else if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) { /* remove all packets in parent bc_buf pointing to this dev */ + __skb_queue_head_init(&freeq); ps = &sdata->bss->ps; spin_lock_irqsave(&ps->bc_buf.lock, flags); @@ -595,10 +596,15 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, bool going_do if (skb->dev == sdata->dev) { __skb_unlink(skb, &ps->bc_buf); local->total_ps_buffered--; - ieee80211_free_txskb(&local->hw, skb); + __skb_queue_tail(&freeq, skb); } } spin_unlock_irqrestore(&ps->bc_buf.lock, flags); + + skb_queue_walk_safe(&freeq, skb, tmp) { + __skb_unlink(skb, &freeq); + ieee80211_free_txskb(&local->hw, skb); + } } if (going_down) |