From 1137e61dcb99f7f8b54e77ed83f68b5b485a3e34 Mon Sep 17 00:00:00 2001
From: Niklas Cassel <niklas.cassel@linaro.org>
Date: Wed, 4 Sep 2019 18:03:38 +0200
Subject: [PATCH] PCI: dwc: Fix find_next_bit() usage
Git-commit: 1137e61dcb99f7f8b54e77ed83f68b5b485a3e34
Patch-mainline: v5.5-rc1
References: bsc#1051510

find_next_bit() takes a parameter of size long, and performs arithmetic
that assumes that the argument is of size long.

Therefore we cannot pass a u32, since this will cause find_next_bit()
to read outside the stack buffer and will produce the following print:
Bug: KASAN: stack-out-of-bounds in find_next_bit+0x38/0xb0

Fixes: 1b497e6493c4 ("PCI: dwc: Fix uninitialized variable in dw_handle_msi_irq()")
Tested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Acked-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/pci/dwc/pcie-designware-host.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- a/drivers/pci/dwc/pcie-designware-host.c
+++ b/drivers/pci/dwc/pcie-designware-host.c
@@ -67,20 +67,21 @@ static struct irq_chip dw_msi_irq_chip =
 /* MSI int handler */
 irqreturn_t dw_handle_msi_irq(struct pcie_port *pp)
 {
-	u32 val;
+	unsigned long val;
+	u32 status;
 	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,
-				    &val);
-		if (!val)
+				    &status);
+		if (!status)
 			continue;
 
 		ret = IRQ_HANDLED;
+		val = status;
 		pos = 0;
-		while ((pos = find_next_bit((unsigned long *) &val, 32,
-					    pos)) != 32) {
+		while ((pos = find_next_bit(&val, 32, pos)) != 32) {
 			irq = irq_find_mapping(pp->irq_domain, i * 32 + pos);
 			generic_handle_irq(irq);
 			pos++;