PCI: keystone: Fix NULL pointer dereference in case of DT error in ks_pcie_setup_rc_a...

If IORESOURCE_MEM is not provided in Device Tree due to
any error, resource_list_first_type() will return NULL and
pci_parse_request_of_pci_ranges() will just emit a warning.

This will cause a NULL pointer dereference. Fix this bug by adding NULL
return check.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 0f71c60ffd26 ("PCI: dwc: Remove storing of PCI resources")
Link: https://lore.kernel.org/linux-pci/20240505061517.11527-1-amishin@t-argos.ru
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Suggested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
index 57135eee2d7d17cdf89f08b9edb8c04f2f98cb10..cd0e0022f91d67af33c62b447aec86460de6d0cd 100644 (file)
--- a/drivers/pci/controller/dwc/pci-keystone.c
+++ b/drivers/pci/controller/dwc/pci-keystone.c
@@ -400,17 +400,22 @@ static const struct irq_domain_ops ks_pcie_intx_irq_domain_ops = {
        .xlate = irq_domain_xlate_onetwocell,
 };
 
-static void ks_pcie_setup_rc_app_regs(struct keystone_pcie *ks_pcie)
+static int ks_pcie_setup_rc_app_regs(struct keystone_pcie *ks_pcie)
 {
        u32 val;
        u32 num_viewport = ks_pcie->num_viewport;
        struct dw_pcie *pci = ks_pcie->pci;
        struct dw_pcie_rp *pp = &pci->pp;
-       u64 start, end;
+       struct resource_entry *entry;
        struct resource *mem;
+       u64 start, end;
        int i;
 
-       mem = resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM)->res;
+       entry = resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM);
+       if (!entry)
+               return -ENODEV;
+
+       mem = entry->res;
        start = mem->start;
        end = mem->end;
 
@@ -421,7 +426,7 @@ static void ks_pcie_setup_rc_app_regs(struct keystone_pcie *ks_pcie)
        ks_pcie_clear_dbi_mode(ks_pcie);
 
        if (ks_pcie->is_am6)
-               return;
+               return 0;
 
        val = ilog2(OB_WIN_SIZE);
        ks_pcie_app_writel(ks_pcie, OB_SIZE, val);
@@ -438,6 +443,8 @@ static void ks_pcie_setup_rc_app_regs(struct keystone_pcie *ks_pcie)
        val = ks_pcie_app_readl(ks_pcie, CMD_STATUS);
        val |= OB_XLAT_EN_VAL;
        ks_pcie_app_writel(ks_pcie, CMD_STATUS, val);
+
+       return 0;
 }
 
 static void __iomem *ks_pcie_other_map_bus(struct pci_bus *bus,
@@ -798,7 +805,10 @@ static int __init ks_pcie_host_init(struct dw_pcie_rp *pp)
                return ret;
 
        ks_pcie_stop_link(pci);
-       ks_pcie_setup_rc_app_regs(ks_pcie);
+       ret = ks_pcie_setup_rc_app_regs(ks_pcie);
+       if (ret)
+               return ret;
+
        writew(PCI_IO_RANGE_TYPE_32 | (PCI_IO_RANGE_TYPE_32 << 8),
                        pci->dbi_base + PCI_IO_BASE);