net: neigh: don't call kfree_skb() under spin_lock_irqsave()

commit d5485d9 upstream. It is not allowed to call kfree_skb() from hardware interrupt context or with interrupts being disabled. So add all skb to a tmp list, then free them after spin_unlock_irqrestore() at once. Fixes: 66ba215 ("neigh: fix possible DoS due to net iface start/stop loop") Suggested-by: Denis V. Lunev <[email protected]> Signed-off-by: Yang Yingliang <[email protected]> Reviewed-by: Nikolay Aleksandrov <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
anthraxx · Sep 5, 2022 · 123bf15 · 123bf15
1 parent ec274d8
commit 123bf15
Showing 1 changed file with 8 additions and 2 deletions.
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
@@ -309,21 +309,27 @@ static int neigh_del_timer(struct neighbour *n)
 
 static void pneigh_queue_purge(struct sk_buff_head *list, struct net *net)
 {
+	struct sk_buff_head tmp;
 	unsigned long flags;
 	struct sk_buff *skb;
 
+	skb_queue_head_init(&tmp);
 	spin_lock_irqsave(&list->lock, flags);
 	skb = skb_peek(list);
 	while (skb != NULL) {
 		struct sk_buff *skb_next = skb_peek_next(skb, list);
 		if (net == NULL || net_eq(dev_net(skb->dev), net)) {
 			__skb_unlink(skb, list);
-			dev_put(skb->dev);
-			kfree_skb(skb);
+			__skb_queue_tail(&tmp, skb);
 		}
 		skb = skb_next;
 	}
 	spin_unlock_irqrestore(&list->lock, flags);
+
+	while ((skb = __skb_dequeue(&tmp))) {
+		dev_put(skb->dev);
+		kfree_skb(skb);
+	}
 }
 
 static void neigh_flush_dev(struct neigh_table *tbl, struct net_device *dev,