PCI: j721e: Initialize pcie->cdns_pcie before using it

Christian reported a NULL pointer dereference in j721e_pcie_probe() caused
by 19e863828acf ("PCI: j721e: Drop redundant struct device *"), which
removed struct j721e_pcie.dev since there's another copy in struct
cdns_pcie.dev reachable via j721e_pcie->cdns_pcie->dev.

The problem is that j721e_pcie->cdns_pcie was dereferenced before being
initialized:

  j721e_pcie_probe
    pcie = devm_kzalloc()             # struct j721e_pcie
    j721e_pcie_ctrl_init(pcie)
      dev = pcie->cdns_pcie->dev      <-- dereference cdns_pcie
    switch (mode) {
    case PCI_MODE_RC:
      cdns_pcie = ...                 # alloc as part of pci_host_bridge
      pcie->cdns_pcie = cdns_pcie     <-- initialize pcie->cdns_pcie

Move the cdns_pcie initialization earlier so it is done before it is used.
This also simplifies the error exits.

Fixes: 19e863828acf ("PCI: j721e: Drop redundant struct device *")
Link: https://lore.kernel.org/r/20220127222951.GA144828@bhelgaas
Link: https://lore.kernel.org/r/20220124122132.435743-1-christian.gmeiner@gmail.com
Reported-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Tested-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c
index 489586a4cdc7b8443eda32f63f84819ebaa89e74..768d33f9ebc87569d4e247bba2588a958e529b40 100644 (file)
--- a/drivers/pci/controller/cadence/pci-j721e.c
+++ b/drivers/pci/controller/cadence/pci-j721e.c
@@ -356,8 +356,8 @@ static int j721e_pcie_probe(struct platform_device *pdev)
        const struct j721e_pcie_data *data;
        struct cdns_pcie *cdns_pcie;
        struct j721e_pcie *pcie;
-       struct cdns_pcie_rc *rc;
-       struct cdns_pcie_ep *ep;
+       struct cdns_pcie_rc *rc = NULL;
+       struct cdns_pcie_ep *ep = NULL;
        struct gpio_desc *gpiod;
        void __iomem *base;
        struct clk *clk;
@@ -376,6 +376,46 @@ static int j721e_pcie_probe(struct platform_device *pdev)
        if (!pcie)
                return -ENOMEM;
 
+       switch (mode) {
+       case PCI_MODE_RC:
+               if (!IS_ENABLED(CONFIG_PCIE_CADENCE_HOST))
+                       return -ENODEV;
+
+               bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
+               if (!bridge)
+                       return -ENOMEM;
+
+               if (!data->byte_access_allowed)
+                       bridge->ops = &cdns_ti_pcie_host_ops;
+               rc = pci_host_bridge_priv(bridge);
+               rc->quirk_retrain_flag = data->quirk_retrain_flag;
+               rc->quirk_detect_quiet_flag = data->quirk_detect_quiet_flag;
+
+               cdns_pcie = &rc->pcie;
+               cdns_pcie->dev = dev;
+               cdns_pcie->ops = &j721e_pcie_ops;
+               pcie->cdns_pcie = cdns_pcie;
+               break;
+       case PCI_MODE_EP:
+               if (!IS_ENABLED(CONFIG_PCIE_CADENCE_EP))
+                       return -ENODEV;
+
+               ep = devm_kzalloc(dev, sizeof(*ep), GFP_KERNEL);
+               if (!ep)
+                       return -ENOMEM;
+
+               ep->quirk_detect_quiet_flag = data->quirk_detect_quiet_flag;
+
+               cdns_pcie = &ep->pcie;
+               cdns_pcie->dev = dev;
+               cdns_pcie->ops = &j721e_pcie_ops;
+               pcie->cdns_pcie = cdns_pcie;
+               break;
+       default:
+               dev_err(dev, "INVALID device type %d\n", mode);
+               return 0;
+       }
+
        pcie->mode = mode;
        pcie->linkdown_irq_regfield = data->linkdown_irq_regfield;
 
@@ -426,28 +466,6 @@ static int j721e_pcie_probe(struct platform_device *pdev)
 
        switch (mode) {
        case PCI_MODE_RC:
-               if (!IS_ENABLED(CONFIG_PCIE_CADENCE_HOST)) {
-                       ret = -ENODEV;
-                       goto err_get_sync;
-               }
-
-               bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
-               if (!bridge) {
-                       ret = -ENOMEM;
-                       goto err_get_sync;
-               }
-
-               if (!data->byte_access_allowed)
-                       bridge->ops = &cdns_ti_pcie_host_ops;
-               rc = pci_host_bridge_priv(bridge);
-               rc->quirk_retrain_flag = data->quirk_retrain_flag;
-               rc->quirk_detect_quiet_flag = data->quirk_detect_quiet_flag;
-
-               cdns_pcie = &rc->pcie;
-               cdns_pcie->dev = dev;
-               cdns_pcie->ops = &j721e_pcie_ops;
-               pcie->cdns_pcie = cdns_pcie;
-
                gpiod = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
                if (IS_ERR(gpiod)) {
                        ret = PTR_ERR(gpiod);
@@ -497,23 +515,6 @@ static int j721e_pcie_probe(struct platform_device *pdev)
 
                break;
        case PCI_MODE_EP:
-               if (!IS_ENABLED(CONFIG_PCIE_CADENCE_EP)) {
-                       ret = -ENODEV;
-                       goto err_get_sync;
-               }
-
-               ep = devm_kzalloc(dev, sizeof(*ep), GFP_KERNEL);
-               if (!ep) {
-                       ret = -ENOMEM;
-                       goto err_get_sync;
-               }
-               ep->quirk_detect_quiet_flag = data->quirk_detect_quiet_flag;
-
-               cdns_pcie = &ep->pcie;
-               cdns_pcie->dev = dev;
-               cdns_pcie->ops = &j721e_pcie_ops;
-               pcie->cdns_pcie = cdns_pcie;
-
                ret = cdns_pcie_init_phy(dev, cdns_pcie);
                if (ret) {
                        dev_err(dev, "Failed to init phy\n");
@@ -525,8 +526,6 @@ static int j721e_pcie_probe(struct platform_device *pdev)
                        goto err_pcie_setup;
 
                break;
-       default:
-               dev_err(dev, "INVALID device type %d\n", mode);
        }
 
        return 0;