ch9200: use skb_cow_head() to deal with cloned skbs

commit 6bc6895bdd6744e0136eaa4a11fbdb20a7db4e40 upstream.

We need to ensure there is enough headroom to push extra header,
but we also need to check if we are allowed to change headers.

skb_cow_head() is the proper helper to deal with this.

Fixes: 4a476bd6d1d9 ("usbnet: New driver for QinHeng CH9200 devices")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: James Hughes <james.hughes@raspberrypi.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/usb/ch9200.c b/drivers/net/usb/ch9200.c
index 5e151e6..3c7715e 100644 (file)
--- a/drivers/net/usb/ch9200.c
+++ b/drivers/net/usb/ch9200.c
@@ -255,14 +255,9 @@ static struct sk_buff *ch9200_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
        tx_overhead = 0x40;
 
        len = skb->len;
-       if (skb_headroom(skb) < tx_overhead) {
-               struct sk_buff *skb2;
-
-               skb2 = skb_copy_expand(skb, tx_overhead, 0, flags);
+       if (skb_cow_head(skb, tx_overhead)) {
                dev_kfree_skb_any(skb);
-               skb = skb2;
-               if (!skb)
-                       return NULL;
+               return NULL;
        }
 
        __skb_push(skb, tx_overhead);