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* [PATCH] xen/netback: Reset nr_frags before freeing skb
@ 2019-08-05 15:34 Ross Lagerwall
  2019-08-09  1:02 ` David Miller
  0 siblings, 1 reply; 2+ messages in thread
From: Ross Lagerwall @ 2019-08-05 15:34 UTC (permalink / raw)
  To: netdev; +Cc: xen-devel, David S. Miller, Paul Durrant, Wei Liu, Ross Lagerwall

At this point nr_frags has been incremented but the frag does not yet
have a page assigned so freeing the skb results in a crash. Reset
nr_frags before freeing the skb to prevent this.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
---
 drivers/net/xen-netback/netback.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 1d9940d4e8c7..c9262ffeefe4 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -925,6 +925,7 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
 			skb_shinfo(skb)->nr_frags = MAX_SKB_FRAGS;
 			nskb = xenvif_alloc_skb(0);
 			if (unlikely(nskb == NULL)) {
+				skb_shinfo(skb)->nr_frags = 0;
 				kfree_skb(skb);
 				xenvif_tx_err(queue, &txreq, extra_count, idx);
 				if (net_ratelimit())
@@ -940,6 +941,7 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
 
 			if (xenvif_set_skb_gso(queue->vif, skb, gso)) {
 				/* Failure in xenvif_set_skb_gso is fatal. */
+				skb_shinfo(skb)->nr_frags = 0;
 				kfree_skb(skb);
 				kfree_skb(nskb);
 				break;
-- 
2.17.2


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] xen/netback: Reset nr_frags before freeing skb
  2019-08-05 15:34 [PATCH] xen/netback: Reset nr_frags before freeing skb Ross Lagerwall
@ 2019-08-09  1:02 ` David Miller
  0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2019-08-09  1:02 UTC (permalink / raw)
  To: ross.lagerwall; +Cc: netdev, xen-devel, paul.durrant, wei.liu

From: Ross Lagerwall <ross.lagerwall@citrix.com>
Date: Mon, 5 Aug 2019 16:34:34 +0100

> At this point nr_frags has been incremented but the frag does not yet
> have a page assigned so freeing the skb results in a crash. Reset
> nr_frags before freeing the skb to prevent this.
> 
> Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>

Applied and queued up for -stable.

^ permalink raw reply	[flat|nested] 2+ messages in thread

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