[PATCH 4.19 036/425] xhci: fix potential array out of bounds with several interrupters

[Greg Kroah-Hartman]

From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>

[ Upstream commit 286fd02fd54b6acab65809549cf5fb3f2a886696 ]

The Max Interrupters supported by the controller is given in a 10bit
wide bitfield, but the driver uses a fixed 128 size array to index these
interrupters.

Klockwork reports a possible array out of bounds case which in theory
is possible. In practice this hasn't been hit as a common number of Max
Interrupters for new controllers is 8, not even close to 128.

This needs to be fixed anyway

Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210406070208.3406266-4-mathias.nyman@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/usb/host/xhci.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index fc07d68fdd15..9ca59f3fffde 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -227,6 +227,7 @@ static void xhci_zero_64b_regs(struct xhci_hcd *xhci)
 	struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
 	int err, i;
 	u64 val;
+	u32 intrs;
 
 	/*
 	 * Some Renesas controllers get into a weird state if they are
@@ -265,7 +266,10 @@ static void xhci_zero_64b_regs(struct xhci_hcd *xhci)
 	if (upper_32_bits(val))
 		xhci_write_64(xhci, 0, &xhci->op_regs->cmd_ring);
 
-	for (i = 0; i < HCS_MAX_INTRS(xhci->hcs_params1); i++) {
+	intrs = min_t(u32, HCS_MAX_INTRS(xhci->hcs_params1),
+		      ARRAY_SIZE(xhci->run_regs->ir_set));
+
+	for (i = 0; i < intrs; i++) {
 		struct xhci_intr_reg __iomem *ir;
 
 		ir = &xhci->run_regs->ir_set[i];
-- 
2.30.2