l2tp: fix race in l2tp_recv_dequeue()
Misha Labjuk reported panics occurring in l2tp_recv_dequeue()
If we release reorder_q.lock, we must not keep a dangling pointer (tmp),
since another thread could manipulate reorder_q.
Instead we must restart the scan at beginning of list.
Reported-by: Misha Labjuk <spiked.yar@gmail.com>
Tested-by: Misha Labjuk <spiked.yar@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 34b2dde..bf8d50c 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -397,6 +397,7 @@
* expect to send up next, dequeue it and any other
* in-sequence packets behind it.
*/
+start:
spin_lock_bh(&session->reorder_q.lock);
skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
@@ -433,7 +434,7 @@
*/
spin_unlock_bh(&session->reorder_q.lock);
l2tp_recv_dequeue_skb(session, skb);
- spin_lock_bh(&session->reorder_q.lock);
+ goto start;
}
out: