drm/amd/display: Ensure index calculation will not overflow

From Alex Hung
3dc6bb57dab36b38b7374af0ac916174c146b6ed in linux-6.6.y/6.6.50
8e2734bf444767fed787305ccdcb36a2be5301a2 in mainline linux

diff --git a/sys/dev/pci/drm/amd/display/dc/dml/calcs/dcn_calcs.c b/sys/dev/pci/drm/amd/display/dc/dml/calcs/dcn_calcs.c
index 50b0434..c08169d 100644 (file)
--- a/sys/dev/pci/drm/amd/display/dc/dml/calcs/dcn_calcs.c
+++ b/sys/dev/pci/drm/amd/display/dc/dml/calcs/dcn_calcs.c
@@ -1453,10 +1453,9 @@ void dcn_bw_update_from_pplib_fclks(
        ASSERT(fclks->num_levels);
 
        vmin0p65_idx = 0;
-       vmid0p72_idx = fclks->num_levels -
-               (fclks->num_levels > 2 ? 3 : (fclks->num_levels > 1 ? 2 : 1));
-       vnom0p8_idx = fclks->num_levels - (fclks->num_levels > 1 ? 2 : 1);
-       vmax0p9_idx = fclks->num_levels - 1;
+       vmid0p72_idx = fclks->num_levels > 2 ? fclks->num_levels - 3 : 0;
+       vnom0p8_idx = fclks->num_levels > 1 ? fclks->num_levels - 2 : 0;
+       vmax0p9_idx = fclks->num_levels > 0 ? fclks->num_levels - 1 : 0;
 
        dc->dcn_soc->fabric_and_dram_bandwidth_vmin0p65 =
                32 * (fclks->data[vmin0p65_idx].clocks_in_khz / 1000.0) / 1000.0;