linux-kernel - [PATCH 3.16 025/134] PCI: dwc: Fix uninitialized variable in dw_handle_msi

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Date:   Fri, 18 Aug 2017 14:13:20 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Dan Carpenter" <dan.carpenter@...cle.com>,
        "Bjorn Helgaas" <bhelgaas@...gle.com>
Subject: [PATCH 3.16 025/134] PCI: dwc: Fix uninitialized variable in
 dw_handle_msi_irq()

3.16.47-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@...cle.com>

commit 1b497e6493c49bbb55c89f53562f7f853495e90d upstream.

The bug is that "val" is unsigned long but we only initialize 32 bits of
it.  Then we test "if (val)" and that might be true not because we set the
bits but because some were never initialized.

Fixes: f342d940ee0e ("PCI: exynos: Add support for MSI")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
[bwh: Backported to 3.16: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/pci/host/pcie-designware.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/pci/host/pcie-designware.c
+++ b/drivers/pci/host/pcie-designware.c
@@ -158,19 +158,20 @@ static struct irq_chip dw_msi_irq_chip =
 /* MSI int handler */
 irqreturn_t dw_handle_msi_irq(struct pcie_port *pp)
 {
-	unsigned long val;
+	u32 val;
 	int i, pos, irq;
 	irqreturn_t ret = IRQ_NONE;
 
 	for (i = 0; i < MAX_MSI_CTRLS; i++) {
 		dw_pcie_rd_own_conf(pp, PCIE_MSI_INTR0_STATUS + i * 12, 4,
-				(u32 *)&val);
+				    &val);
 		if (!val)
 			continue;
 
 		ret = IRQ_HANDLED;
 		pos = 0;
-		while ((pos = find_next_bit(&val, 32, pos)) != 32) {
+		while ((pos = find_next_bit((unsigned long *) &val, 32,
+					    pos)) != 32) {
 			irq = irq_find_mapping(pp->irq_domain, i * 32 + pos);
 			dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_STATUS + i * 12,
 					    4, 1 << pos);