2018-08-09 14:43:30

by Juergen Gross

Subject: [PATCH] xen/netfront: don't cache skb_shinfo()

skb_shinfo() can change when calling __pskb_pull_tail(): Don't cache
its return value.

Cc: [email protected]
Signed-off-by: Juergen Gross <[email protected]>
---
drivers/net/xen-netfront.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 2d8812dd1534..9dd2ca62d84a 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -894,7 +894,6 @@ static RING_IDX xennet_fill_frags(struct netfront_queue *queue,
struct sk_buff *skb,
struct sk_buff_head *list)
{
- struct skb_shared_info *shinfo = skb_shinfo(skb);
RING_IDX cons = queue->rx.rsp_cons;
struct sk_buff *nskb;

@@ -903,15 +902,16 @@ static RING_IDX xennet_fill_frags(struct netfront_queue *queue,
RING_GET_RESPONSE(&queue->rx, ++cons);
skb_frag_t *nfrag = &skb_shinfo(nskb)->frags[0];

- if (shinfo->nr_frags == MAX_SKB_FRAGS) {
+ if (skb_shinfo(skb)->nr_frags == MAX_SKB_FRAGS) {
unsigned int pull_to = NETFRONT_SKB_CB(skb)->pull_to;

BUG_ON(pull_to <= skb_headlen(skb));
__pskb_pull_tail(skb, pull_to - skb_headlen(skb));
}
- BUG_ON(shinfo->nr_frags >= MAX_SKB_FRAGS);
+ BUG_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS);

- skb_add_rx_frag(skb, shinfo->nr_frags, skb_frag_page(nfrag),
+ skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
+ skb_frag_page(nfrag),
rx->offset, rx->status, PAGE_SIZE);

skb_shinfo(nskb)->nr_frags = 0;
--
2.13.7

2018-08-09 14:48:34

by Wei Liu

Subject: Re: [Xen-devel] [PATCH] xen/netfront: don't cache skb_shinfo()

On Thu, Aug 09, 2018 at 04:42:16PM +0200, Juergen Gross wrote:
> skb_shinfo() can change when calling __pskb_pull_tail(): Don't cache
> its return value.
>
> Cc: [email protected]
> Signed-off-by: Juergen Gross <[email protected]>

Reviewed-by: Wei Liu <[email protected]>

2018-08-11 16:43:41

by David Miller

Subject: Re: [PATCH] xen/netfront: don't cache skb_shinfo()

From: Juergen Gross <[email protected]>
Date: Thu, 9 Aug 2018 16:42:16 +0200

> skb_shinfo() can change when calling __pskb_pull_tail(): Don't cache
> its return value.
>
> Cc: [email protected]
> Signed-off-by: Juergen Gross <[email protected]>

Applied.