net: ll_temac: Fix potential NULL dereference in temac_probe()

[ Upstream commit cc6596fc72 ]

platform_get_resource() may fail and in this case a NULL dereference
will occur.

Fix it to use devm_platform_ioremap_resource() instead of calling
platform_get_resource() and devm_ioremap().

This is detected by Coccinelle semantic patch.

@@
expression pdev, res, n, t, e, e1, e2;
@@

res = \(platform_get_resource\|platform_get_resource_byname\)(pdev, t, n);
+ if (!res)
+   return -EINVAL;
... when != res == NULL
e = devm_ioremap(e1, res->start, e2);

Fixes: 8425c41d1e ("net: ll_temac: Extend support to non-device-tree platforms")
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Acked-by: Esben Haabendal <esben@geanix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/xilinx/ll_temac_main.c

@@ -1425,9 +1425,7 @@ static int temac_probe(struct platform_device *pdev)
 		of_node_put(dma_np);
 	} else if (pdata) {
 		/* 2nd memory resource specifies DMA registers */
-		res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
-		lp->sdma_regs = devm_ioremap_nocache(&pdev->dev, res->start,
-						     resource_size(res));
+		lp->sdma_regs = devm_platform_ioremap_resource(pdev, 1);
 		if (IS_ERR(lp->sdma_regs)) {
 			dev_err(&pdev->dev,
 				"could not map DMA registers\n");