[PATCH] net: dwc-xlgmac: set skb to NULL after freeing it

[Pan Bian]

The buffer skb is freed via dev_kfree_skb in a loop. After freeing skb,
the value of packet_count is updated via packet_count++. If packet_count
happens to equal the upper bound (i.e., budget), the loop will be broken
and skb may be assigned to desc_data->state.skb. Resulting that
desc_data->state.skb may point to a freed memory chunk. To fix this, the
patch sets skb to NULL after dev_kfree_skb(skb).

Signed-off-by: Pan Bian <bianpan2...@163.com>
---
 drivers/net/ethernet/synopsys/dwc-xlgmac-net.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/synopsys/dwc-xlgmac-net.c 
b/drivers/net/ethernet/synopsys/dwc-xlgmac-net.c
index 1f8e960..a0d28c4 100644
--- a/drivers/net/ethernet/synopsys/dwc-xlgmac-net.c
+++ b/drivers/net/ethernet/synopsys/dwc-xlgmac-net.c
@@ -1180,6 +1180,7 @@ static int xlgmac_rx_poll(struct xlgmac_channel *channel, 
int budget)
                                netif_err(pdata, rx_err, netdev,
                                          "error in received packet\n");
                        dev_kfree_skb(skb);
+                       skb = NULL;
                        goto next_packet;
                }
 
@@ -1227,6 +1228,7 @@ static int xlgmac_rx_poll(struct xlgmac_channel *channel, 
int budget)
                        netif_err(pdata, rx_err, netdev,
                                  "packet length exceeds configured MTU\n");
                        dev_kfree_skb(skb);
+                       skb = NULL;
                        goto next_packet;
                }
 
-- 
2.7.4