mmc: moxart: Fix null pointer dereference on pointer host

There are several error return paths that dereference the null pointer
host because the pointer has not yet been set to a valid value.
Fix this by adding a new out_mmc label and exiting via this label
to avoid the host clean up and hence the null pointer dereference.

Addresses-Coverity: ("Explicit null dereference")
Fixes: 8105c2ab ("mmc: moxart: Fix reference count leaks in moxart_probe")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20211013100052.125461-1-colin.king@canonical.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/moxart-mmc.c

@@ -566,37 +566,37 @@ static int moxart_probe(struct platform_device *pdev)
 	if (!mmc) {
 		dev_err(dev, "mmc_alloc_host failed\n");
 		ret = -ENOMEM;
-		goto out;
+		goto out_mmc;
 	}
 
 	ret = of_address_to_resource(node, 0, &res_mmc);
 	if (ret) {
 		dev_err(dev, "of_address_to_resource failed\n");
-		goto out;
+		goto out_mmc;
 	}
 
 	irq = irq_of_parse_and_map(node, 0);
 	if (irq <= 0) {
 		dev_err(dev, "irq_of_parse_and_map failed\n");
 		ret = -EINVAL;
-		goto out;
+		goto out_mmc;
 	}
 
 	clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(clk)) {
 		ret = PTR_ERR(clk);
-		goto out;
+		goto out_mmc;
 	}
 
 	reg_mmc = devm_ioremap_resource(dev, &res_mmc);
 	if (IS_ERR(reg_mmc)) {
 		ret = PTR_ERR(reg_mmc);
-		goto out;
+		goto out_mmc;
 	}
 
 	ret = mmc_of_parse(mmc);
 	if (ret)
-		goto out;
+		goto out_mmc;
 
 	host = mmc_priv(mmc);
 	host->mmc = mmc;
@@ -687,6 +687,7 @@ static int moxart_probe(struct platform_device *pdev)
 		dma_release_channel(host->dma_chan_tx);
 	if (!IS_ERR_OR_NULL(host->dma_chan_rx))
 		dma_release_channel(host->dma_chan_rx);
+out_mmc:
 	if (mmc)
 		mmc_free_host(mmc);
 	return ret;