[PATCH net-next v2 13/15] xen-netfront: don't BUG() when skb_copy_bits() fails in bounce_skb()

bounce_skb() is an open-coded skb_copy() for skbs whose data isn't
page-aligned, and it has the same BUG_ON(skb_copy_bits()).
skb_copy_bits() only fails when the skb's lengths don't add up.

bounce_skb() already frees the new skb and returns NULL when the
allocation comes back misaligned, and xennet_start_xmit() drops the
packet in that case.  Take the same path, with a
DEBUG_NET_WARN_ON_ONCE() for debug kernels.

Assisted-by: LLM
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 drivers/net/xen-netfront.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index fdcb91042f29..17811d81937c 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c

@@ -695,7 +695,12 @@ static struct sk_buff *bounce_skb(const struct sk_buff *skb)
 	/* Set the tail pointer and length */
 	skb_put(n, skb->len);
 
-	BUG_ON(skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len));
+	if (unlikely(skb_copy_bits(skb, -headerlen, n->head,
+				   headerlen + skb->len))) {
+		DEBUG_NET_WARN_ON_ONCE(1);
+		kfree_skb(n);
+		return NULL;
+	}
 
 	skb_copy_header(n, skb);
 	return n;

-- 
2.55.0