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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Pavel Skripkin <paskripkin@gmail.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.13 126/156] net: moxa: fix UAF in moxart_mac_probe
Date:   Thu, 22 Jul 2021 18:31:41 +0200
Message-Id: <20210722155632.436280693@linuxfoundation.org>
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References: <20210722155628.371356843@linuxfoundation.org>
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From: Pavel Skripkin <paskripkin@gmail.com>

commit c78eaeebe855fd93f2e77142ffd0404a54070d84 upstream.

In case of netdev registration failure the code path will
jump to init_fail label:

init_fail:
	netdev_err(ndev, "init failed\n");
	moxart_mac_free_memory(ndev);
irq_map_fail:
	free_netdev(ndev);
	return ret;

So, there is no need to call free_netdev() before jumping
to error handling path, since it can cause UAF or double-free
bug.

Fixes: 6c821bd9edc9 ("net: Add MOXA ART SoCs ethernet driver")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/moxa/moxart_ether.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/drivers/net/ethernet/moxa/moxart_ether.c
+++ b/drivers/net/ethernet/moxa/moxart_ether.c
@@ -540,10 +540,8 @@ static int moxart_mac_probe(struct platf
 	SET_NETDEV_DEV(ndev, &pdev->dev);
 
 	ret = register_netdev(ndev);
-	if (ret) {
-		free_netdev(ndev);
+	if (ret)
 		goto init_fail;
-	}
 
 	netdev_dbg(ndev, "%s: IRQ=%d address=%pM\n",
 		   __func__, ndev->irq, ndev->dev_addr);