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authorEric Dumazet <eric.dumazet@gmail.com>2011-11-02 22:47:44 +0000
committerDavid S. Miller <davem@davemloft.net>2011-11-03 18:02:13 -0400
commite2e210c0238eb7073e07af503ae743fa53977120 (patch)
treea4940a436eb0292f09a9e9c09d7bfccfc5a0d76f
parent2edcd4ca43df3c1d1d392753531cc73a53e709ba (diff)
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>
-rw-r--r--net/l2tp/l2tp_core.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 34b2ddeacb6..bf8d50c6793 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -397,6 +397,7 @@ static void l2tp_recv_dequeue(struct l2tp_session *session)
* 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 @@ static void l2tp_recv_dequeue(struct l2tp_session *session)
*/
spin_unlock_bh(&session->reorder_q.lock);
l2tp_recv_dequeue_skb(session, skb);
- spin_lock_bh(&session->reorder_q.lock);
+ goto start;
}
out: