The driver was making changes to the skb_header without
ensuring it was writable (i.e. uncloned).
This patch also removes some boiler plate header size
checking/adjustment code as that is also handled by the
skb_cow_header function used to make header writable.

This patch depends on
brcmfmac: Ensure pointer correctly set if skb data location changes

Signed-off-by: James Hughes <james.hug...@raspberrypi.org>
---
Changes in v2
  Makes the _cow_ call at the entry point of the skb in to the
  stack, means only needs to be done once, and error handling
  is easier.
  Split a separate minor bug fix off to a separate patch (which
  this patch depends on)



 .../net/wireless/broadcom/brcm80211/brcmfmac/core.c   | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c 
b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
index 9b7c19a508ac..88f8675a94c2 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
@@ -211,22 +211,11 @@ static netdev_tx_t brcmf_netdev_start_xmit(struct sk_buff 
*skb,
                goto done;
        }
 
-       /* Make sure there's enough room for any header */
-       if (skb_headroom(skb) < drvr->hdrlen) {
-               struct sk_buff *skb2;
-
-               brcmf_dbg(INFO, "%s: insufficient headroom\n",
-                         brcmf_ifname(ifp));
-               drvr->bus_if->tx_realloc++;
-               skb2 = skb_realloc_headroom(skb, drvr->hdrlen);
+       /* Make sure there's enough room for any header, and make it writable */
+       if (skb_cow_head(skb, drvr->hdrlen)) {
                dev_kfree_skb(skb);
-               skb = skb2;
-               if (skb == NULL) {
-                       brcmf_err("%s: skb_realloc_headroom failed\n",
-                                 brcmf_ifname(ifp));
-                       ret = -ENOMEM;
-                       goto done;
-               }
+               ret = -ENOMEM;
+               goto done;
        }
 
        /* validate length for ether packet */
-- 
2.11.0

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