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From: Aleksandr Mishin <amishin@t-argos.ru>
To: Rob Herring <robh@kernel.org>
CC: Aleksandr Mishin <amishin@t-argos.ru>, Lorenzo Pieralisi
	<lpieralisi@kernel.org>, =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?=
	<kw@linux.com>, Bjorn Helgaas <bhelgaas@google.com>, Manivannan Sadhasivam
	<manivannan.sadhasivam@linaro.org>, =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?=
	<u.kleine-koenig@pengutronix.de>, Serge Semin <fancer.lancer@gmail.com>,
	Niklas Cassel <cassel@kernel.org>, Yoshihiro Shimoda
	<yoshihiro.shimoda.uh@renesas.com>, Damien Le Moal <dlemoal@kernel.org>,
	Siddharth Vadapalli <s-vadapalli@ti.com>, <linux-pci@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <lvc-project@linuxtesting.org>, Bjorn Helgaas
	<helgaas@kernel.org>
Subject: [PATCH v4] PCI: dwc: keystone: Fix NULL pointer dereference in case  of DT error in ks_pcie_setup_rc_app_regs()
Date: Sun, 5 May 2024 09:15:17 +0300
Message-ID: <20240505061517.11527-1-amishin@t-argos.ru>
In-Reply-To: <20240329051947.28900-1-amishin@t-argos.ru>
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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