[PATCH] USB: gadget: max3420: validate endpoint index in set_clear_feature

[Kery Qi <qikeyu2017@gmail.com>]

Assure that the host may not manipulate the index to point past the
endpoint array.

In max3420_set_clear_feature(), the driver derives the endpoint
index from the wIndex field of the setup packet. However, there is
no check to ensure this index is within the valid bounds of the
udc->ep[] array.

A malicious host could send a USB_REQ_SET_FEATURE or
USB_REQ_CLEAR_FEATURE request with a large endpoint index, leading
to an out-of-bounds memory access when accessing udc->ep[id].

This patch adds a validation check against MAX3420_MAX_EPS. If the
endpoint index is invalid, we simply break the switch statement
to invoke the existing error handling path.

Signed-off-by: Kery Qi <qikeyu2017@gmail.com>
---
 drivers/usb/gadget/udc/max3420_udc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/gadget/udc/max3420_udc.c b/drivers/usb/gadget/udc/max3420_udc.c
index ac11ddf3fcbc..f4f549d88d6d 100644
--- a/drivers/usb/gadget/udc/max3420_udc.c
+++ b/drivers/usb/gadget/udc/max3420_udc.c
@@ -600,6 +600,8 @@ static void max3420_set_clear_feature(struct max3420_udc *udc)
 			break;
 
 		id = udc->setup.wIndex & USB_ENDPOINT_NUMBER_MASK;
+		if (id >= MAX3420_MAX_EPS)
+			break;
 		ep = &udc->ep[id];
 
 		spin_lock_irqsave(&ep->lock, flags);
-- 
2.34.1