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From:   Wang Hai <wanghai38@huawei.com>
To:     <jesse.brandeburg@intel.com>, <anthony.l.nguyen@intel.com>,
        <baijiaju1990@163.com>, <jeffrey.t.kirsher@intel.com>,
        <davem@davemloft.net>, <edumazet@google.com>, <kuba@kernel.org>,
        <pabeni@redhat.com>
CC:     <linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>,
        <intel-wired-lan@lists.osuosl.org>
Subject: [PATCH net] e100: Fix possible use after free in e100_xmit_prepare
Date:   Wed, 16 Nov 2022 01:24:07 +0800
Message-ID: <20221115172407.72863-1-wanghai38@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

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@huawei.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
-- 
2.17.1