[PATCH] PCI: dwc: Fix potential NULL dereference

[Aleksandr Mishin]

In al_pcie_config_prepare() 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@xxxxxxxxxx>
---
 drivers/pci/controller/dwc/pcie-al.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-al.c b/drivers/pci/controller/dwc/pcie-al.c
index 6dfdda59f328..29bc99d48295 100644
--- a/drivers/pci/controller/dwc/pcie-al.c
+++ b/drivers/pci/controller/dwc/pcie-al.c
@@ -252,7 +252,12 @@ static void al_pcie_config_prepare(struct al_pcie *pcie)
 	u8 secondary_bus;
 	u32 cfg_control;
 	u32 reg;
-	struct resource *bus = resource_list_first_type(&pp->bridge->windows, IORESOURCE_BUS)->res;
+
+	struct resource_entry *ft = resource_list_first_type(&pp->bridge->windows, IORESOURCE_BUS); 
+	if (!ft)
+		return;
+
+	struct resource *bus = ft->res;
 
 	target_bus_cfg = &pcie->target_bus_cfg;
 
-- 
2.30.2