[PATCH] ACPI: PCI: Clear driver_data on all error paths in acpi_pci_root_add()

[Chen Pei]

acpi_pci_root_add() assigns the freshly allocated root to
device->driver_data before dmar_device_add() and pci_acpi_scan_root().
Both failure paths reach the end: label where root is kfree()'d, but
only the pci_acpi_scan_root() path clears driver_data first.

When dmar_device_add() fails during a hot-add, root is freed while
device->driver_data still points at it.  The ACPI core does not clear
driver_data on attach failure, so a later acpi_pci_find_root() call
may dereference this dangling pointer.

Move the NULL assignment to the shared end: label so every error path
clears driver_data before freeing root.

Fixes: db89b4f0dbab ("ACPI: catch calls of acpi_driver_data on pointer of wrong type")
Reported-by: Sashiko AI review <sashiko-bot@xxxxxxxxxx>
Link: https://sashiko.dev/#/patchset/20260526025118.38935-1-cp0613@xxxxxxxxxxxxxxxxx
Signed-off-by: Chen Pei <cp0613@xxxxxxxxxxxxxxxxx>
---
 drivers/acpi/pci_root.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 4c06c3ffd0cb..f6cddd11075c 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -725,7 +725,6 @@ static int acpi_pci_root_add(struct acpi_device *device,
 		dev_err(&device->dev,
 			"Bus %04x:%02x not present in PCI namespace\n",
 			root->segment, (unsigned int)root->secondary.start);
-		device->driver_data = NULL;
 		result = -ENODEV;
 		goto remove_dmar;
 	}
@@ -765,6 +764,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	if (hotadd)
 		dmar_device_remove(handle);
 end:
+	device->driver_data = NULL;
 	kfree(root);
 	return result;
 }
-- 
2.50.1