From: Juergen Gross Date: Tue, 11 Sep 2018 07:04:48 +0000 (+0200) Subject: xen/netfront: don't bug in case of too many frags X-Git-Tag: v4.14.73~35 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7eced4478f4ec6ff0a603ddfd6e24a5d3831fca7;p=users%2Fjedix%2Flinux-maple.git xen/netfront: don't bug in case of too many frags 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 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index d80343429de5..1a40fc3517a8 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -907,7 +907,11 @@ static RING_IDX xennet_fill_frags(struct netfront_queue *queue, 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;