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Commit 1425c7a4 authored by Paul Durrant's avatar Paul Durrant Committed by David S. Miller
Browse files

xen-netback: BUG_ON in xenvif_rx_action() not catching overflow 



The BUG_ON to catch ring overflow in xenvif_rx_action() makes the assumption
that meta_slots_used == ring slots used. This is not necessarily the case
for GSO packets, because the non-prefix GSO protocol consumes one more ring
slot than meta-slot for the 'extra_info'. This patch changes the test to
actually check ring slots.

Signed-off-by: default avatarPaul Durrant <paul.durrant@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a02eb473

drivers/net/xen-netback/netback.c

+7 −1
Original line number Original line Diff line number Diff line
@@ -482,6 +482,8 @@ static void xenvif_rx_action(struct xenvif *vif) 




	while ((skb = skb_dequeue(&vif->rx_queue)) != NULL) {

	while ((skb = skb_dequeue(&vif->rx_queue)) != NULL) {

		RING_IDX max_slots_needed;

		RING_IDX max_slots_needed;

		RING_IDX old_req_cons;

		RING_IDX ring_slots_used;

		int i;

		int i;





		/* We need a cheap worse case estimate for the number of

		/* We need a cheap worse case estimate for the number of
@@ -530,8 +532,12 @@ static void xenvif_rx_action(struct xenvif *vif) 
			vif->rx_last_skb_slots = 0;

			vif->rx_last_skb_slots = 0;





		sco = (struct skb_cb_overlay *)skb->cb;

		sco = (struct skb_cb_overlay *)skb->cb;



		old_req_cons = vif->rx.req_cons;

		sco->meta_slots_used = xenvif_gop_skb(skb, &npo);

		sco->meta_slots_used = xenvif_gop_skb(skb, &npo);

		BUG_ON(sco->meta_slots_used > max_slots_needed);

		ring_slots_used = vif->rx.req_cons - old_req_cons;



		BUG_ON(ring_slots_used > max_slots_needed);





		__skb_queue_tail(&rxq, skb);

		__skb_queue_tail(&rxq, skb);

	}

	}