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net: mediatek: Fix potential NULL pointer dereference in dummy net_de…
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…vice handling

Move the freeing of the dummy net_device from mtk_free_dev() to
mtk_remove().

Previously, if alloc_netdev_dummy() failed in mtk_probe(),
eth->dummy_dev would be NULL. The error path would then call
mtk_free_dev(), which in turn called free_netdev() assuming dummy_dev
was allocated (but it was not), potentially causing a NULL pointer
dereference.

By moving free_netdev() to mtk_remove(), we ensure it's only called when
mtk_probe() has succeeded and dummy_dev is fully allocated. This
addresses a potential NULL pointer dereference detected by Smatch[1].

Fixes: b209bd6 ("net: mediatek: mtk_eth_sock: allocate dummy net_device dynamically")
Reported-by: Dan Carpenter <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/ [1]
Suggested-by: Dan Carpenter <[email protected]>
Reviewed-by: Dan Carpenter <[email protected]>
Signed-off-by: Breno Leitao <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>
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leitao authored and Paolo Abeni committed Jul 25, 2024
1 parent e6d08d7 commit 16f3a28
Showing 1 changed file with 1 addition and 2 deletions.
3 changes: 1 addition & 2 deletions drivers/net/ethernet/mediatek/mtk_eth_soc.c
Original file line number Diff line number Diff line change
Expand Up @@ -4223,8 +4223,6 @@ static int mtk_free_dev(struct mtk_eth *eth)
metadata_dst_free(eth->dsa_meta[i]);
}

free_netdev(eth->dummy_dev);

return 0;
}

Expand Down Expand Up @@ -5090,6 +5088,7 @@ static void mtk_remove(struct platform_device *pdev)
netif_napi_del(&eth->tx_napi);
netif_napi_del(&eth->rx_napi);
mtk_cleanup(eth);
free_netdev(eth->dummy_dev);
mtk_mdio_cleanup(eth);
}

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