[ I fixed a Smatch bug and now it started warning about this code -dan ]
Hello Johannes Berg,
This is a semi-automatic email about new static checker warnings.
The patch 531682159092: "mac80211: fix VLAN handling with TXQs" from
Jun 22, 2017, leads to the following Smatch complaint:
net/mac80211/tx.c:3529 ieee80211_tx_dequeue()
error: we previously assumed 'skb' could be null (see line 3511)
net/mac80211/tx.c
3500 tx.key, skb);
3501 } else {
3502 if (invoke_tx_handlers_late(&tx))
3503 goto begin;
3504
3505 skb = __skb_dequeue(&tx.skbs);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The NULL skb would have to come from here.
3506
3507 if (!skb_queue_empty(&tx.skbs))
3508 skb_queue_splice_tail(&tx.skbs, &txqi->frags);
3509 }
3510
3511 if (skb && skb_has_frag_list(skb) &&
^^^
Old code checks
3512 !ieee80211_hw_check(&local->hw, TX_FRAG_LIST)) {
3513 if (skb_linearize(skb)) {
3514 ieee80211_free_txskb(&local->hw, skb);
3515 goto begin;
3516 }
3517 }
3518
3519 switch (tx.sdata->vif.type) {
3520 case NL80211_IFTYPE_MONITOR:
3521 if (tx.sdata->u.mntr.flags & MONITOR_FLAG_ACTIVE) {
3522 vif = &tx.sdata->vif;
3523 break;
3524 }
3525 tx.sdata = rcu_dereference(local->monitor_sdata);
3526 if (tx.sdata) {
3527 vif = &tx.sdata->vif;
3528 info->hw_queue =
3529
vif->hw_queue[skb_get_queue_mapping(skb)];
^^^
Patch adds unchecked dereference (might be a false positive).
3530 } else if (ieee80211_hw_check(&local->hw,
QUEUE_CONTROL)) {
3531 ieee80211_free_txskb(&local->hw, skb);
regards,
dan carpenter
