diff options
| author | Dongli Zhang <dongli.zhang@oracle.com> | 2019-09-16 11:46:59 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-09-21 07:14:09 +0200 |
| commit | 08ea4ff33d782f7f2924644d122b6fcb9d43abff (patch) | |
| tree | 15d9d41d683f53e922e421245ea95a1a52f190a5 | |
| parent | f8bfa2fd7cc7114ab552a662662dfede0914903e (diff) | |
| download | linux-rt-08ea4ff33d782f7f2924644d122b6fcb9d43abff.tar.gz | |
xen-netfront: do not assume sk_buff_head list is empty in error handling
[ Upstream commit 00b368502d18f790ab715e055869fd4bb7484a9b ]
When skb_shinfo(skb) is not able to cache extra fragment (that is,
skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS), xennet_fill_frags() assumes
the sk_buff_head list is already empty. As a result, cons is increased only
by 1 and returns to error handling path in xennet_poll().
However, if the sk_buff_head list is not empty, queue->rx.rsp_cons may be
set incorrectly. That is, queue->rx.rsp_cons would point to the rx ring
buffer entries whose queue->rx_skbs[i] and queue->grant_rx_ref[i] are
already cleared to NULL. This leads to NULL pointer access in the next
iteration to process rx ring buffer entries.
Below is how xennet_poll() does error handling. All remaining entries in
tmpq are accounted to queue->rx.rsp_cons without assuming how many
outstanding skbs are remained in the list.
985 static int xennet_poll(struct napi_struct *napi, int budget)
... ...
1032 if (unlikely(xennet_set_skb_gso(skb, gso))) {
1033 __skb_queue_head(&tmpq, skb);
1034 queue->rx.rsp_cons += skb_queue_len(&tmpq);
1035 goto err;
1036 }
It is better to always have the error handling in the same way.
Fixes: ad4f15dc2c70 ("xen/netfront: don't bug in case of too many frags")
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/net/xen-netfront.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 14ceeaaa7fe5..c31c564b8eab 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -907,7 +907,7 @@ static RING_IDX xennet_fill_frags(struct netfront_queue *queue, __pskb_pull_tail(skb, pull_to - skb_headlen(skb)); } if (unlikely(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS)) { - queue->rx.rsp_cons = ++cons; + queue->rx.rsp_cons = ++cons + skb_queue_len(list); kfree_skb(nskb); return ~0U; } |