[bug report] PCI/ACPI: Fix allocated memory release on error in pci_acpi_scan_root()

[Dan Carpenter <dan.carpenter@linaro.org>]

Hello Zhe Qiao,

Commit 631b2af2f357 ("PCI/ACPI: Fix allocated memory release on error
in pci_acpi_scan_root()") from Apr 30, 2025 (linux-next), leads to
the following Smatch static checker warning:

	drivers/pci/pci-acpi.c:1712 pci_acpi_scan_root()
	error: double free of 'root_ops' (line 1711)

drivers/pci/pci-acpi.c
    1667 struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
    1668 {
    1669         struct acpi_pci_generic_root_info *ri;
    1670         struct pci_bus *bus, *child;
    1671         struct acpi_pci_root_ops *root_ops;
    1672         struct pci_host_bridge *host;
    1673 
    1674         ri = kzalloc(sizeof(*ri), GFP_KERNEL);
    1675         if (!ri)
    1676                 return NULL;
    1677 
    1678         root_ops = kzalloc(sizeof(*root_ops), GFP_KERNEL);
    1679         if (!root_ops)
    1680                 goto free_ri;
    1681 
    1682         ri->cfg = pci_acpi_setup_ecam_mapping(root);
    1683         if (!ri->cfg)
    1684                 goto free_root_ops;
    1685 
    1686         root_ops->release_info = pci_acpi_generic_release_info;
    1687         root_ops->prepare_resources = pci_acpi_root_prepare_resources;
    1688         root_ops->pci_ops = (struct pci_ops *)&ri->cfg->ops->pci_ops;
    1689         bus = acpi_pci_root_create(root, root_ops, &ri->common, ri->cfg);
    1690         if (!bus)
    1691                 goto free_cfg;

The acpi_pci_root_create() function frees root_ops on error in
pci_acpi_generic_release_info().  I think there is only one error
path where it frees "ri->cfg".  I probably would advise you to re-write
the the error handling in acpi_pci_root_create().

    1692 
    1693         /* If we must preserve the resource configuration, claim now */
    1694         host = pci_find_host_bridge(bus);
    1695         if (host->preserve_config)
    1696                 pci_bus_claim_resources(bus);
    1697 
    1698         /*
    1699          * Assign whatever was left unassigned. If we didn't claim above,
    1700          * this will reassign everything.
    1701          */
    1702         pci_assign_unassigned_root_bus_resources(bus);
    1703 
    1704         list_for_each_entry(child, &bus->children, node)
    1705                 pcie_bus_configure_settings(child);
    1706 
    1707         return bus;
    1708 
    1709 free_cfg:
    1710         pci_ecam_free(ri->cfg);
    1711 free_root_ops:
--> 1712         kfree(root_ops);
    1713 free_ri:
    1714         kfree(ri);
    1715         return NULL;
    1716 }

regards,
dan carpenter