usb: xhci-mtk: fix issue of out-of-bounds array access

commit de5107f upstream.

Bus bandwidth array access is based on esit, increase one
will cause out-of-bounds issue; for example, when esit is
XHCI_MTK_MAX_ESIT, will overstep boundary.

Fixes: 7c986fb ("usb: xhci-mtk: get the microframe boundary for ESIT")
Cc: <stable@vger.kernel.org>
Reported-by: Stan Lu <stan.lu@mediatek.com>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1629189389-18779-5-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-mtk-sch.c

@@ -590,10 +590,12 @@ static u32 get_esit_boundary(struct mu3h_sch_ep_info *sch_ep)
 	u32 boundary = sch_ep->esit;
 
 	if (sch_ep->sch_tt) { /* LS/FS with TT */
-		/* tune for CS */
-		if (sch_ep->ep_type != ISOC_OUT_EP)
-			boundary++;
-		else if (boundary > 1) /* normally esit >= 8 for FS/LS */
+		/*
+		 * tune for CS, normally esit >= 8 for FS/LS,
+		 * not add one for other types to avoid access array
+		 * out of boundary
+		 */
+		if (sch_ep->ep_type == ISOC_OUT_EP && boundary > 1)
 			boundary--;
 	}