usb: musb: Fix musb_gadget.c rxstate overflow bug

The usb function device call musb_gadget_queue() adds the passed
request to musb_ep::req_list,If the (request->length > musb_ep->packet_sz)
and (is_buffer_mapped(req) return false),the rxstate() will copy all data
in fifo to request->buf which may cause request->buf out of bounds.

Fix it by add the length check :
fifocnt = min_t(unsigned, request->length - request->actual, fifocnt);

Signed-off-by: Robin Guo <guoweibin@inspur.com>
Link: https://lore.kernel.org/r/20220906102119.1b071d07a8391ff115e6d1ef@inspur.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/musb_gadget.c

@@ -760,6 +760,9 @@ static void rxstate(struct musb *musb, struct musb_request *req)
 			musb_writew(epio, MUSB_RXCSR, csr);
 
 buffer_aint_mapped:
+			fifo_count = min_t(unsigned int,
+					request->length - request->actual,
+					(unsigned int)fifo_count);
 			musb_read_fifo(musb_ep->hw_ep, fifo_count, (u8 *)
 					(request->buf + request->actual));
 			request->actual += fifo_count;