[PATCH v3 1/3] net: dsa: ksz: Check return value

[Artem Chernyshev]

Return NULL if we got unexpected value from skb_trim_rcsum() 
in ksz_common_rcv()

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: bafe9ba7d908 ("net: dsa: ksz: Factor out common tag code")
Signed-off-by: Artem Chernyshev <artem.chernyshev@xxxxxxxxxxx>
Reviewed-by: Vladimir Oltean <olteanv@xxxxxxxxx>
---
V1->V2 Fixes for tag_hellcreek.c and tag_sja1105.c
V2->V3 Split patch in 3 separate parts

 net/dsa/tag_ksz.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index 38fa19c1e2d5..429250298ac4 100644
--- a/net/dsa/tag_ksz.c
+++ b/net/dsa/tag_ksz.c
@@ -21,7 +21,8 @@ static struct sk_buff *ksz_common_rcv(struct sk_buff *skb,
 	if (!skb->dev)
 		return NULL;
 
-	pskb_trim_rcsum(skb, skb->len - len);
+	if (pskb_trim_rcsum(skb, skb->len - len))
+		return NULL;
 
 	dsa_default_offload_fwd_mark(skb);
 
-- 
2.30.3