4.18-stable review patch. If anyone has any objections, please let me know.
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From: Juergen Gross jgross@suse.com
commit ad4f15dc2c70b1de5e0a64d27335962fbc9cf71c upstream.
Commit 57f230ab04d291 ("xen/netfront: raise max number of slots in xennet_get_responses()") raised the max number of allowed slots by one. This seems to be problematic in some configurations with netback using a larger MAX_SKB_FRAGS value (e.g. old Linux kernel with MAX_SKB_FRAGS defined as 18 instead of nowadays 17).
Instead of BUG_ON() in this case just fall back to retransmission.
Fixes: 57f230ab04d291 ("xen/netfront: raise max number of slots in xennet_get_responses()") Cc: stable@vger.kernel.org Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/net/xen-netfront.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
--- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -907,7 +907,11 @@ static RING_IDX xennet_fill_frags(struct BUG_ON(pull_to <= skb_headlen(skb)); __pskb_pull_tail(skb, pull_to - skb_headlen(skb)); } - BUG_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS); + if (unlikely(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS)) { + queue->rx.rsp_cons = ++cons; + kfree_skb(nskb); + return ~0U; + }
skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, skb_frag_page(nfrag), @@ -1044,6 +1048,8 @@ err: skb->len += rx->status;
i = xennet_fill_frags(queue, skb, &tmpq); + if (unlikely(i == ~0U)) + goto err;
if (rx->flags & XEN_NETRXF_csum_blank) skb->ip_summed = CHECKSUM_PARTIAL;