[PATCH v2 2/2] usb: gadget: max3420_udc: Fix out-of-bounds endpoint index access

[Seungjin Bae]

Similar to max3420_set_clear_feature() function, the max3420_getstatus() function also fails to validate the endpoint index
from wIndex before using it to access the udc->ep array.

The udc->ep array is initialized to handle 4 endpoints, but the index derived from the `wIndex & USB_ENDPOINT_NUMBER_MASK`
can be up to 15. This can lead to an out-of-bounds access, causing memory corruption or a potential kernel crash.
This bug was found by code inspection and has not been tested on hardware.

Fixes: 48ba02b2e2b1a ("usb: gadget: add udc driver for max3420")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Seungjin Bae <eeodqql09@xxxxxxxxx>
---
 v1 -> v2: Added a second patch to fix an out-of-bounds bug in the max3420_getstatus() function.
 
 drivers/usb/gadget/udc/max3420_udc.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/udc/max3420_udc.c b/drivers/usb/gadget/udc/max3420_udc.c
index e4ecc7f7f3be..ff6c7f9d71d8 100644
--- a/drivers/usb/gadget/udc/max3420_udc.c
+++ b/drivers/usb/gadget/udc/max3420_udc.c
@@ -536,6 +536,7 @@ static void max3420_getstatus(struct max3420_udc *udc)
 {
 	struct max3420_ep *ep;
 	u16 status = 0;
+	int id;
 
 	switch (udc->setup.bRequestType & USB_RECIP_MASK) {
 	case USB_RECIP_DEVICE:
@@ -548,7 +549,10 @@ static void max3420_getstatus(struct max3420_udc *udc)
 			goto stall;
 		break;
 	case USB_RECIP_ENDPOINT:
-		ep = &udc->ep[udc->setup.wIndex & USB_ENDPOINT_NUMBER_MASK];
+		id = udc->setup.wIndex & USB_ENDPOINT_NUMBER_MASK;
+		if (id >= MAX3420_MAX_EPS)
+			goto stall;
+		ep = &udc->ep[id];
 		if (udc->setup.wIndex & USB_DIR_IN) {
 			if (!ep->ep_usb.caps.dir_in)
 				goto stall;
-- 
2.43.0