netdev - [PATCH net 5/5] e100: Fix possible use after free in e100_xmit

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Date:   Wed, 23 Nov 2022 15:04:06 -0800
From:   Tony Nguyen <anthony.l.nguyen@...el.com>
To:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        edumazet@...gle.com
Cc:     Wang Hai <wanghai38@...wei.com>, netdev@...r.kernel.org,
        anthony.l.nguyen@...el.com, baijiaju1990@....com,
        Alexander Duyck <alexanderduyck@...com>
Subject: [PATCH net 5/5] e100: Fix possible use after free in e100_xmit_prepare

From: Wang Hai <wanghai38@...wei.com>

In e100_xmit_prepare(), if we can't map the skb, then return -ENOMEM, so
e100_xmit_frame() will return NETDEV_TX_BUSY and the upper layer will
resend the skb. But the skb is already freed, which will cause UAF bug
when the upper layer resends the skb.

Remove the harmful free.

Fixes: 5e5d49422dfb ("e100: Release skb when DMA mapping is failed in e100_xmit_prepare")
Signed-off-by: Wang Hai <wanghai38@...wei.com>
Reviewed-by: Alexander Duyck <alexanderduyck@...com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 drivers/net/ethernet/intel/e100.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/e100.c b/drivers/net/ethernet/intel/e100.c
index 560d1d442232..d3fdc290937f 100644
--- a/drivers/net/ethernet/intel/e100.c
+++ b/drivers/net/ethernet/intel/e100.c
@@ -1741,11 +1741,8 @@ static int e100_xmit_prepare(struct nic *nic, struct cb *cb,
 	dma_addr = dma_map_single(&nic->pdev->dev, skb->data, skb->len,
 				  DMA_TO_DEVICE);
 	/* If we can't map the skb, have the upper layer try later */
-	if (dma_mapping_error(&nic->pdev->dev, dma_addr)) {
-		dev_kfree_skb_any(skb);
-		skb = NULL;
+	if (dma_mapping_error(&nic->pdev->dev, dma_addr))
 		return -ENOMEM;
-	}
 
 	/*
 	 * Use the last 4 bytes of the SKB payload packet as the CRC, used for
-- 
2.35.1