Re: [PATCH AUTOSEL 5.15 25/47] PCI: al: Check IORESOURCE_BUS existence during probe

Pavel Machek
2024-08-27T12:23:28Z

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Hi!

> [ Upstream commit a9927c2cac6e9831361e43a14d91277818154e6a ]
>
> If IORESOURCE_BUS is not provided in Device Tree it will be fabricated in
> of_pci_parse_bus_range(), so NULL pointer dereference should not happen
> here.
>
> But that's hard to verify, so check for NULL anyway.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.

If the NULL can't happen, we should not really apply this to -stable.

Best regards,
Pavel

> +++ b/drivers/pci/controller/dwc/pcie-al.c
> @@ -242,18 +242,24 @@ static struct pci_ops al_child_pci_ops = {
> .write = pci_generic_config_write,
> };
>
> -static void al_pcie_config_prepare(struct al_pcie *pcie)
> +static int al_pcie_config_prepare(struct al_pcie *pcie)
> {
> struct al_pcie_target_bus_cfg *target_bus_cfg;
> struct pcie_port *pp = &pcie->pci->pp;
> unsigned int ecam_bus_mask;
> + struct resource_entry *ft;
> u32 cfg_control_offset;
> + struct resource *bus;
> u8 subordinate_bus;
> u8 secondary_bus;
> u32 cfg_control;
> u32 reg;
> - struct resource *bus = resource_list_first_type(&pp->bridge->windows, IORESOURCE_BUS)->res;
>
> + ft = resource_list_first_type(&pp->bridge->windows, IORESOURCE_BUS);
> + if (!ft)
> + return -ENODEV;
> +
> + bus = ft->res;
> target_bus_cfg = &pcie->target_bus_cfg;
>
> ecam_bus_mask = (pcie->ecam_size >> PCIE_ECAM_BUS_SHIFT) - 1;
> @@ -287,6 +293,8 @@ static void al_pcie_config_prepare(struct al_pcie *pcie)
> FIELD_PREP(CFG_CONTROL_SEC_BUS_MASK, secondary_bus);
>
> al_pcie_controller_writel(pcie, cfg_control_offset, reg);
> +
> + return 0;
> }
>
> static int al_pcie_host_init(struct pcie_port *pp)
> @@ -305,7 +313,9 @@ static int al_pcie_host_init(struct pcie_port *pp)
> if (rc)
> return rc;
>
> - al_pcie_config_prepare(pcie);
> + rc = al_pcie_config_prepare(pcie);
> + if (rc)
> + return rc;
>
> return 0;
> }

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