drm/amdgpu: Clamp the ATIF backlight curve to its 99 points

amdgpu_atif_query_backlight_caps() stores the firmware's number_of_points
as data_points but copies only the 99 points that luminance_data[] holds.
number_of_points is a u8, so a firmware table that claims more makes the
custom curve code in amdgpu_dm index past the array, and
dm_query_extended_brightness_caps() copy past the end of the
data_points[] buffer it fills

Clamp the count to ATIF_QBTC_MAX_DATA_POINTS and warn, since a table
that claims more is a firmware bug

Fixes: f729e63743f0 ("drm/amd: Pass luminance data to amdgpu_dm_backlight_caps")
Signed-off-by: Hugo Sales <hugo@hsal.es>
Link: https://patch.msgid.link/20261031153948.127016-1-hugo@hsal.es
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit af8a1c2b7d3de4960e10f94e8ba2fc0ccd168072)
Cc: stable@vger.kernel.org

0 files changed, 0 insertions, 0 deletions