From e9156cd26a495a18706e796f02a81fee41ec14f4 Mon Sep 17 00:00:00 2001 From: James Hughes <james.hughes@raspberrypi.org> Date: Wed, 19 Apr 2017 11:13:40 +0100 Subject: [PATCH] smsc95xx: Use skb_cow_head to deal with cloned skbs The driver was failing to check that the SKB wasn't cloned before adding checksum data. Replace existing handling to extend/copy the header buffer with skb_cow_head. Signed-off-by: James Hughes <james.hughes@raspberrypi.org> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Woojung Huh <Woojung.Huh@microchip.com> Signed-off-by: David S. Miller <davem@davemloft.net> --- drivers/net/usb/smsc95xx.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/drivers/net/usb/smsc95xx.c +++ b/drivers/net/usb/smsc95xx.c @@ -1835,13 +1835,13 @@ static struct sk_buff *smsc95xx_tx_fixup /* We do not advertise SG, so skbs should be already linearized */ BUG_ON(skb_shinfo(skb)->nr_frags); - if (skb_headroom(skb) < overhead) { - struct sk_buff *skb2 = skb_copy_expand(skb, - overhead, 0, flags); + /* Make writable and expand header space by overhead if required */ + if (skb_cow_head(skb, overhead)) { + /* Must deallocate here as returning NULL to indicate error + * means the skb won't be deallocated in the caller. + */ dev_kfree_skb_any(skb); - skb = skb2; - if (!skb) - return NULL; + return NULL; } if (csum) {