linux-kernel - [PATCH] amd-xgbe: set skb to NULL after freeing it

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Date:   Wed, 28 Nov 2018 16:09:45 +0800
From:   Pan Bian <bianpan2016@....com>
To:     Tom Lendacky <thomas.lendacky@....com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pan Bian <bianpan2016@....com>
Subject: [PATCH] amd-xgbe: set skb to NULL after freeing it

The buffer skb is freed via dev_kfree_skb in a loop. skb may be used
again in the next iteration, resulting in a use-after-free bug. To fix
this, the patch set skb to NULL after dev_kfree_skb(skb).

Signed-off-by: Pan Bian <bianpan2016@....com>
---
 drivers/net/ethernet/amd/xgbe/xgbe-drv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
index 0cc911f..ac6b82d 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -2754,6 +2754,7 @@ static int xgbe_rx_poll(struct xgbe_channel *channel, int budget)
 				netif_err(pdata, rx_err, netdev,
 					  "error in received packet\n");
 			dev_kfree_skb(skb);
+			skb = NULL;
 			goto next_packet;
 		}
 
@@ -2806,6 +2807,7 @@ static int xgbe_rx_poll(struct xgbe_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