net: nixge: Fix error path for obtaining mac address

Fix issue where nixge_get_nvmem_address() returns a non-NULL
return value on a failed nvmem_cell_get() that causes an invalid
access when error value encoded in pointer is dereferenced.

Furthermore ensure that buffer allocated by nvmem_cell_read()
actually gets kfreed() if the function succeeds.

Fixes commit 492caffa8a1a ("net: ethernet: nixge: Add support for
National Instruments XGE netdev")
Reported-by: Alex Williams <alex.williams@ni.com>
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/ni/nixge.c b/drivers/net/ethernet/ni/nixge.c
index 27364b7572fc157dad85ddddc905510b1c96701c..c41fea9253e35ac2dfb435ed32ea211d996af0dc 100644 (file)
--- a/drivers/net/ethernet/ni/nixge.c
+++ b/drivers/net/ethernet/ni/nixge.c
@@ -1170,7 +1170,7 @@ static void *nixge_get_nvmem_address(struct device *dev)
 
        cell = nvmem_cell_get(dev, "address");
        if (IS_ERR(cell))
-               return cell;
+               return NULL;
 
        mac = nvmem_cell_read(cell, &cell_size);
        nvmem_cell_put(cell);
@@ -1202,10 +1202,12 @@ static int nixge_probe(struct platform_device *pdev)
        ndev->max_mtu = NIXGE_JUMBO_MTU;
 
        mac_addr = nixge_get_nvmem_address(&pdev->dev);
-       if (mac_addr && is_valid_ether_addr(mac_addr))
+       if (mac_addr && is_valid_ether_addr(mac_addr)) {
                ether_addr_copy(ndev->dev_addr, mac_addr);
-       else
+               kfree(mac_addr);
+       } else {
                eth_hw_addr_random(ndev);
+       }
 
        priv = netdev_priv(ndev);
        priv->ndev = ndev;