[PATCH AUTOSEL 5.10 128/176] usb: chipidea: host: fix port index underflow and UBSAN complains

[Sasha Levin]

From: Li Jun <jun.li@xxxxxxx>

[ Upstream commit e5d6a7c6cfae9e714a0e8ff64facd1ac68a784c6 ]

If wIndex is 0 (and it often is), these calculations underflow and
UBSAN complains, here resolve this by not decrementing the index when
it is equal to 0, this copies the solution from commit 85e3990bea49
("USB: EHCI: avoid undefined pointer arithmetic and placate UBSAN")

Reported-by: Zhipeng Wang <zhipeng.wang_1@xxxxxxx>
Signed-off-by: Li Jun <jun.li@xxxxxxx>
Link: https://lore.kernel.org/r/1624004938-2399-1-git-send-email-jun.li@xxxxxxx
Signed-off-by: Peter Chen <peter.chen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/usb/chipidea/host.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/chipidea/host.c b/drivers/usb/chipidea/host.c
index 48e4a5ca1835..f5f56ee07729 100644
--- a/drivers/usb/chipidea/host.c
+++ b/drivers/usb/chipidea/host.c
@@ -233,18 +233,26 @@ static int ci_ehci_hub_control(
 )
 {
 	struct ehci_hcd	*ehci = hcd_to_ehci(hcd);
+	unsigned int	ports = HCS_N_PORTS(ehci->hcs_params);
 	u32 __iomem	*status_reg;
-	u32		temp;
+	u32		temp, port_index;
 	unsigned long	flags;
 	int		retval = 0;
 	struct device *dev = hcd->self.controller;
 	struct ci_hdrc *ci = dev_get_drvdata(dev);
 
-	status_reg = &ehci->regs->port_status[(wIndex & 0xff) - 1];
+	port_index = wIndex & 0xff;
+	port_index -= (port_index > 0);
+	status_reg = &ehci->regs->port_status[port_index];
 
 	spin_lock_irqsave(&ehci->lock, flags);
 
 	if (typeReq == SetPortFeature && wValue == USB_PORT_FEAT_SUSPEND) {
+		if (!wIndex || wIndex > ports) {
+			retval = -EPIPE;
+			goto done;
+		}
+
 		temp = ehci_readl(ehci, status_reg);
 		if ((temp & PORT_PE) == 0 || (temp & PORT_RESET) != 0) {
 			retval = -EPIPE;
@@ -273,7 +281,7 @@ static int ci_ehci_hub_control(
 			ehci_writel(ehci, temp, status_reg);
 		}
 
-		set_bit((wIndex & 0xff) - 1, &ehci->suspended_ports);
+		set_bit(port_index, &ehci->suspended_ports);
 		goto done;
 	}
 
-- 
2.30.2