[PATCH][net-next v1] gianfar: Fix alloc_skb_resources on -ENOMEM cleanup path

Should gfar_init_bds() return with -ENOMEM inside gfar_alloc_skb_resources(),
free_skb_resources() will be called twice in a row on the "cleanup" path,
leading to duplicate kfree() calls for rx_|tx_queue->rx_|tx_skbuff resulting
in segmentation fault.
This patch prevents the segmentation fault to happen in the future
(rx_|tx_sbkbuff set to NULL), and corrects the error path handling
for gfar_init_bds().

Cc: Paul Gortmaker <redacted>
Cc: "David S. Miller" <davem@davemloft.net>

Signed-off-by: Claudiu Manoil <redacted>
---
v1: do free_skb_resources() on the cleanup path of gfar_init_bds()'s parent

 drivers/net/ethernet/freescale/gianfar.c |   16 ++++++++++------
 1 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c
index 1d03dcd..ce2007f 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c

@@ -210,7 +210,7 @@ static int gfar_init_bds(struct net_device *ndev)
 				skb = gfar_new_skb(ndev);
 				if (!skb) {
 					netdev_err(ndev, "Can't allocate RX buffers\n");
-					goto err_rxalloc_fail;
+					return -ENOMEM;
 				}
 				rx_queue->rx_skbuff[j] = skb;
 

@@ -223,10 +223,6 @@ static int gfar_init_bds(struct net_device *ndev)
 	}
 
 	return 0;
-
-err_rxalloc_fail:
-	free_skb_resources(priv);
-	return -ENOMEM;
 }
 
 static int gfar_alloc_skb_resources(struct net_device *ndev)

@@ -1356,7 +1352,9 @@ static int gfar_restore(struct device *dev)
 	if (!netif_running(ndev))
 		return 0;
 
-	gfar_init_bds(ndev);
+	if (gfar_init_bds(ndev))
+		goto cleanup;
+

 	init_registers(ndev);
 	gfar_set_mac_address(ndev);
 	gfar_init_mac(ndev);

@@ -1373,6 +1371,10 @@ static int gfar_restore(struct device *dev)
 	enable_napi(priv);
 
 	return 0;
+
+cleanup:
+	free_skb_resources(priv);
+	return -ENOMEM;
 }
 
 static struct dev_pm_ops gfar_pm_ops = {

@@ -1709,6 +1711,7 @@ static void free_skb_tx_queue(struct gfar_priv_tx_q *tx_queue)
 		tx_queue->tx_skbuff[i] = NULL;
 	}
 	kfree(tx_queue->tx_skbuff);
+	tx_queue->tx_skbuff = NULL;
 }
 
 static void free_skb_rx_queue(struct gfar_priv_rx_q *rx_queue)

@@ -1732,6 +1735,7 @@ static void free_skb_rx_queue(struct gfar_priv_rx_q *rx_queue)
 		rxbdp++;
 	}
 	kfree(rx_queue->rx_skbuff);
+	rx_queue->rx_skbuff = NULL;
 }
 
 /* If there are any tx skbs or rx skbs still around, free them.