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SubjectRe: [PATCH] Revert "PCI: j721e: Drop redundant struct device *"
On Mon, Jan 24, 2022 at 01:21:22PM +0100, Christian Gmeiner wrote:
> This reverts commit 19e863828acf6d8ac8475ba1fd93c0fe17fdc4ef.
>
> Fixes the following oops:
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010

Hi Christian,

Would you mind trying this patch?

commit 9d36a93af8fe ("PCI: j721e: Initialize pcie->cdns_pcie before using it")
Author: Bjorn Helgaas <bhelgaas@google.com>
Date: Thu Jan 27 15:49:49 2022 -0600

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

Initialize pcie->cdns_pcie before it is used.

Fixes: 19e863828acf ("PCI: j721e: Drop redundant struct device *")
Reported-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Link: https://lore.kernel.org/r/20220124122132.435743-1-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 489586a4cdc7..5d950c1d9fd0 100644
--- a/drivers/pci/controller/cadence/pci-j721e.c
+++ b/drivers/pci/controller/cadence/pci-j721e.c
@@ -372,10 +372,48 @@ static int j721e_pcie_probe(struct platform_device *pdev)

mode = (u32)data->mode;

+ 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;
+ 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;
+ break;
+ default:
+ dev_err(dev, "INVALID device type %d\n", mode);
+ return 0;
+ }
+
+ cdns_pcie->dev = dev;
+ cdns_pcie->ops = &j721e_pcie_ops;
+
pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
if (!pcie)
return -ENOMEM;

+ pcie->cdns_pcie = cdns_pcie;
pcie->mode = mode;
pcie->linkdown_irq_regfield = data->linkdown_irq_regfield;

@@ -426,28 +464,6 @@ 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 +513,6 @@ 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 +524,6 @@ 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;
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