[PATCH v2] PCI: dwc: keystone: Fix potential NULL dereference

[Aleksandr Mishin <amishin@t-argos.ru>]

In ks_pcie_setup_rc_app_regs() resource_list_first_type() may return
NULL which is later dereferenced. Fix this bug by adding NULL check.

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

Fixes: 0f71c60ffd26 ("PCI: dwc: Remove storing of PCI resources")
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
---
v2: Add return code processing

 drivers/pci/controller/dwc/pci-keystone.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
index 844de4418724..5c6786d9f3e9 100644
--- a/drivers/pci/controller/dwc/pci-keystone.c
+++ b/drivers/pci/controller/dwc/pci-keystone.c
@@ -382,17 +382,22 @@ static void ks_pcie_clear_dbi_mode(struct keystone_pcie *ks_pcie)
 	} while (val & DBI_CS2);
 }
 
-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 *ft;
 	struct resource *mem;
+	u64 start, end;
 	int i;
 
-	mem = resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM)->res;
+	ft = resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM);
+	if (!ft)
+		return -EINVAL;
+
+	mem = ft->res;
 	start = mem->start;
 	end = mem->end;
 
@@ -403,7 +408,7 @@ 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);
@@ -420,6 +425,8 @@ 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,
@@ -814,7 +821,10 @@ 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 < 0)
+		return ret;
+
 	writew(PCI_IO_RANGE_TYPE_32 | (PCI_IO_RANGE_TYPE_32 << 8),
 			pci->dbi_base + PCI_IO_BASE);
 
-- 
2.30.2