mac80211: validate skb->dev in the tx status path

skb->dev might contain a stale reference to a device that was already
deleted, and using it unchecked can lead to invalid pointer accesses.
Since this is only used for nl80211 tx, iterate over active interfaces
to find a match for skb->dev, and discard the tx status if the device
is gone.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 30 insertions, 18 deletions

diff --git a/net/mac80211/status.c b/net/mac80211/status.c
index b0801b7d572d..2ce89732d0f2 100644
--- a/net/mac80211/status.c
+++ b/net/mac80211/status.c
@@ -517,29 +517,41 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
 
         if (info->flags & IEEE80211_TX_INTFL_NL80211_FRAME_TX) {
                 u64 cookie = (unsigned long)skb;
+                bool found = false;
+
                 acked = info->flags & IEEE80211_TX_STAT_ACK;
 
-                if (ieee80211_is_nullfunc(hdr->frame_control) ||
-                    ieee80211_is_qos_nullfunc(hdr->frame_control)) {
-                        cfg80211_probe_status(skb->dev, hdr->addr1,
-                                              cookie, acked, GFP_ATOMIC);
-                } else if (skb->dev) {
-                        cfg80211_mgmt_tx_status(
-                                skb->dev->ieee80211_ptr, cookie, skb->data,
-                                skb->len, acked, GFP_ATOMIC);
-                } else {
-                        struct ieee80211_sub_if_data *p2p_sdata;
+                rcu_read_lock();
+
+                list_for_each_entry_rcu(sdata, &local->interfaces, list) {
+                        if (!sdata->dev)
+                                continue;
 
-                        rcu_read_lock();
+                        if (skb->dev != sdata->dev)
+                                continue;
 
-                        p2p_sdata = rcu_dereference(local->p2p_sdata);
-                        if (p2p_sdata) {
-                                cfg80211_mgmt_tx_status(
-                                        &p2p_sdata->wdev, cookie, skb->data,
-                                        skb->len, acked, GFP_ATOMIC);
-                        }
-                        rcu_read_unlock();
+                        found = true;
+                        break;
+                }
+
+                if (!skb->dev) {
+                        sdata = rcu_dereference(local->p2p_sdata);
+                        if (sdata)
+                                found = true;
+                }
+
+                if (!found)
+                        skb->dev = NULL;
+                else if (ieee80211_is_nullfunc(hdr->frame_control) ||
+                         ieee80211_is_qos_nullfunc(hdr->frame_control)) {
+                        cfg80211_probe_status(sdata->dev, hdr->addr1,
+                                              cookie, acked, GFP_ATOMIC);
+                } else {
+                        cfg80211_mgmt_tx_status(&sdata->wdev, cookie, skb->data,
+                                                skb->len, acked, GFP_ATOMIC);
                 }
+
+                rcu_read_unlock();
         }
 
         if (unlikely(info->ack_frame_id)) {