[PATCH 4.14 04/52] net: dsa: add error handling for pskb_trim_rcsum

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Zhouyang Jia <jiazhouyang09@gmail.com>

[ Upstream commit 349b71d6f427ff8211adf50839dbbff3f27c1805 ]

When pskb_trim_rcsum fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling pskb_trim_rcsum.

Signed-off-by: Zhouyang Jia <jiazhouyang09@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/dsa/tag_trailer.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/dsa/tag_trailer.c
+++ b/net/dsa/tag_trailer.c
@@ -79,7 +79,8 @@ static struct sk_buff *trailer_rcv(struc
 	if (unlikely(ds->cpu_port_mask & BIT(source_port)))
 		return NULL;
 
-	pskb_trim_rcsum(skb, skb->len - 4);
+	if (pskb_trim_rcsum(skb, skb->len - 4))
+		return NULL;
 
 	skb->dev = ds->ports[source_port].netdev;