5.4-stable review patch. If anyone has any objections, please let me know.
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From: Dmitry Antipov dmantipov@yandex.ru
[ Upstream commit 9d301de12da6e1bb069a9835c38359b8e8135121 ]
Since '__dev_queue_xmit()' should be called with interrupts enabled, the following backtrace:
ieee80211_do_stop() ... spin_lock_irqsave(&local->queue_stop_reason_lock, flags) ... ieee80211_free_txskb() ieee80211_report_used_skb() ieee80211_report_ack_skb() cfg80211_mgmt_tx_status_ext() nl80211_frame_tx_status() genlmsg_multicast_netns() genlmsg_multicast_netns_filtered() nlmsg_multicast_filtered() netlink_broadcast_filtered() do_one_broadcast() netlink_broadcast_deliver() __netlink_sendskb() netlink_deliver_tap() __netlink_deliver_tap_skb() dev_queue_xmit() __dev_queue_xmit() ; with IRQS disabled ... spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags)
issues the warning (as reported by syzbot reproducer):
WARNING: CPU: 2 PID: 5128 at kernel/softirq.c:362 __local_bh_enable_ip+0xc3/0x120
Fix this by implementing a two-phase skb reclamation in 'ieee80211_do_stop()', where actual work is performed outside of a section with interrupts disabled.
Fixes: 5061b0c2b906 ("mac80211: cooperate more with network namespaces") Reported-by: syzbot+1a3986bbd3169c307819@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1a3986bbd3169c307819 Signed-off-by: Dmitry Antipov dmantipov@yandex.ru Link: https://patch.msgid.link/20240906123151.351647-1-dmantipov@yandex.ru Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/mac80211/iface.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c index 1f691180e13db..e49b80a9de520 100644 --- a/net/mac80211/iface.c +++ b/net/mac80211/iface.c @@ -795,6 +795,7 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, { struct ieee80211_local *local = sdata->local; unsigned long flags; + struct sk_buff_head freeq; struct sk_buff *skb, *tmp; u32 hw_reconf_flags = 0; int i, flushed; @@ -993,18 +994,32 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, skb_queue_purge(&sdata->skb_queue); }
+ /* + * Since ieee80211_free_txskb() may issue __dev_queue_xmit() + * which should be called with interrupts enabled, reclamation + * is done in two phases: + */ + __skb_queue_head_init(&freeq); + + /* unlink from local queues... */ spin_lock_irqsave(&local->queue_stop_reason_lock, flags); for (i = 0; i < IEEE80211_MAX_QUEUES; i++) { skb_queue_walk_safe(&local->pending[i], skb, tmp) { struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); if (info->control.vif == &sdata->vif) { __skb_unlink(skb, &local->pending[i]); - ieee80211_free_txskb(&local->hw, skb); + __skb_queue_tail(&freeq, skb); } } } spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags);
+ /* ... and perform actual reclamation with interrupts enabled. */ + skb_queue_walk_safe(&freeq, skb, tmp) { + __skb_unlink(skb, &freeq); + ieee80211_free_txskb(&local->hw, skb); + } + if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) ieee80211_txq_remove_vlan(local, sdata);