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Subject[PATCH v4] PCI: dwc: keystone: Fix NULL pointer dereference in case of DT error in ks_pcie_setup_rc_app_regs()
Date
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")
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Suggested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
v1->v2: Add return code processing as suggested by Bjorn
v2->v3: Return -ENODEV instead of -EINVAL as suggested by Manivannan
v3->v4: Change variable name as suggested by Manivannan,
add "Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>"

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..67415c1a93ff 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 *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;

@@ -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)
+ return ret;
+
writew(PCI_IO_RANGE_TYPE_32 | (PCI_IO_RANGE_TYPE_32 << 8),
pci->dbi_base + PCI_IO_BASE);

--
2.30.2

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