Re: [PATCH 09/11] usb: xhci-mtk: check boundary before check tt

On Mon, 2021-08-09 at 15:32 +0800, Ikjoon Jang wrote:

Hi Chunfeng,

On Fri, Jul 30, 2021 at 4:50 PM Chunfeng Yun <
chunfeng.yun@mediatek.com> wrote:

quoted

check_sch_tt() will access fs_bus_bw[] array, check boundary
firstly to avoid out-of-bounds issue.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
 drivers/usb/host/xhci-mtk-sch.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/host/xhci-mtk-sch.c

b/drivers/usb/host/xhci-mtk-sch.c
index 10c0f0f6461f..c2f13d69c607 100644

--- a/drivers/usb/host/xhci-mtk-sch.c
+++ b/drivers/usb/host/xhci-mtk-sch.c

@@ -600,13 +600,14 @@ static int check_sch_bw(struct

mu3h_sch_bw_info *sch_bw,
         * and find a microframe where its worst bandwidth is
minimum.
         */
        for (offset = 0; offset < sch_ep->esit; offset++) {
-               ret = check_sch_tt(sch_ep, offset);
-               if (ret)
-                       continue;

                if ((offset + sch_ep->num_budget_microframes) >
esit_boundary)
                        break;

Instead of dropping it,
I'm wondering if it should be checked against (offset & 63) == 0 when
it's 64?

No, sch_ep->esit already ensure it, it's <= 64, see get_esit()

quoted

+               ret = check_sch_tt(sch_ep, offset);
+               if (ret)
+                       continue;
+
                worst_bw = get_max_bw(sch_bw, sch_ep, offset);
                if (worst_bw > bw_boundary)
                        continue;
--
2.18.0