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. Please apply to 4.12, important fix. This patch depends on brcmfmac: Ensure pointer correctly set if skb data location changes Signed-off-by: James Hughes <james.hughes@xxxxxxxxxxxxxxx> Acked-by: Arend van Spriel <arend.vanspriel@xxxxxxxxxxxx> --- 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) Changes in v3 Minor change to the 'if' logic to reduce patch size as per maintainers request. Flagged as important fix for 4.12 in commit message .../net/wireless/broadcom/brcm80211/brcmfmac/core.c | 21 ++++++--------------- 1 file changed, 6 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..433f2c8408e9 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c @@ -211,22 +211,13 @@ 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 writable headroom*/ + ret = skb_cow_head(skb, drvr->hdrlen); + if (ret < 0) { + brcmf_err("%s: skb_cow_head failed\n", + brcmf_ifname(ifp)); dev_kfree_skb(skb); - skb = skb2; - if (skb == NULL) { - brcmf_err("%s: skb_realloc_headroom failed\n", - brcmf_ifname(ifp)); - ret = -ENOMEM; - goto done; - } + goto done; } /* validate length for ether packet */ -- 2.11.0