In sys/dev/pci/drm/amd/display/dc/dml/dcn20/display_mode_vba_20.c,
the function dml20_ModeSupportAndSystemConfigurationFull has the
following code:
(link to code location:
https://github.com/openbsd/src/blob/master/sys/dev/pci/drm/amd/display/dc/dml/dcn20/display_mode_vba_20.c#L4257)
/*DSC Delay per state*/
for (i = 0; i <= mode_lib->vba.soc.num_states; i++) {
for (k = 0; k <= mode_lib->vba.NumberOfActivePlanes - 1; k++) {
if (mode_lib->vba.BlendingAndTiming[k] != k) {
mode_lib->vba.slices = 0;
} else if (locals->RequiresDSC[i][k] == 0
|| locals->RequiresDSC[i][k] == false) {
mode_lib->vba.slices = 0;
}
...
if (locals->RequiresDSC[i][k] == true && mode_lib->vba.bpp != 0.0) {
dml_ceil(mode_lib->vba.HActive[k] / mode_lib->vba.slices, 1.0);
}
...
The variable mode_lib->vba.slices is used as a divisor, but its value
may be equal to zero, leading to a divide by zero problem.
Similar issues also appear in the file display_mode_vba_20v2.c and
display_mode_vba_21.c.
