[PATCH 4.4 046/101] bgmac: fix a missing check for build_skb

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: wangweidong <wangweidong1@xxxxxxxxxx>

commit f1640c3ddeec12804bc9a21feee85fc15aca95f6 upstream.

when build_skb failed, it may occure a NULL pointer.
So add a 'NULL check' for it.

Signed-off-by: Weidong Wang <wangweidong1@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Amit Pundir <amit.pundir@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/ethernet/broadcom/bgmac.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/net/ethernet/broadcom/bgmac.c
+++ b/drivers/net/ethernet/broadcom/bgmac.c
@@ -469,6 +469,11 @@ static int bgmac_dma_rx_read(struct bgma
 			len -= ETH_FCS_LEN;
 
 			skb = build_skb(buf, BGMAC_RX_ALLOC_SIZE);
+			if (unlikely(skb)) {
+				bgmac_err(bgmac, "build_skb failed\n");
+				put_page(virt_to_head_page(buf));
+				break;
+			}
 			skb_put(skb, BGMAC_RX_FRAME_OFFSET +
 				BGMAC_RX_BUF_OFFSET + len);
 			skb_pull(skb, BGMAC_RX_FRAME_OFFSET +