drm/amd/display: fix dereference of pointer fs_params before it is null checked

Currently there are several instances of pointer fs_params being
dereferenced before fs_params is being null checked.  Fix this by
only dereferencing fs_params after the null check.

Detected by CoverityScan, CID#1475565 ("Dereference before null check")

Fixes: e1e8a020c6b8 ("drm/amd/display: Add support for Freesync 2 HDR and Content to Display Mapping")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
index 7480f07..bbecbae 100644 (file)
--- a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
+++ b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
@@ -813,20 +813,26 @@ static bool build_freesync_hdr(struct pwl_float_data_ex *rgb_regamma,
        const struct hw_x_point *coord_x = coordinate_x;
        struct fixed31_32 scaledX = dc_fixpt_zero;
        struct fixed31_32 scaledX1 = dc_fixpt_zero;
-       struct fixed31_32 max_display = dc_fixpt_from_int(fs_params->max_display);
-       struct fixed31_32 min_display = dc_fixpt_from_fraction(fs_params->min_display, 10000);
-       struct fixed31_32 max_content = dc_fixpt_from_int(fs_params->max_content);
-       struct fixed31_32 min_content = dc_fixpt_from_fraction(fs_params->min_content, 10000);
+       struct fixed31_32 max_display;
+       struct fixed31_32 min_display;
+       struct fixed31_32 max_content;
+       struct fixed31_32 min_content;
        struct fixed31_32 clip = dc_fixpt_one;
        struct fixed31_32 output;
        bool use_eetf = false;
        bool is_clipped = false;
-       struct fixed31_32 sdr_white_level = dc_fixpt_from_int(fs_params->sdr_white_level);
+       struct fixed31_32 sdr_white_level;
 
        if (fs_params == NULL || fs_params->max_content == 0 ||
                        fs_params->max_display == 0)
                return false;
 
+       max_display = dc_fixpt_from_int(fs_params->max_display);
+       min_display = dc_fixpt_from_fraction(fs_params->min_display, 10000);
+       max_content = dc_fixpt_from_int(fs_params->max_content);
+       min_content = dc_fixpt_from_fraction(fs_params->min_content, 10000);
+       sdr_white_level = dc_fixpt_from_int(fs_params->sdr_white_level);
+
        if (fs_params->min_display > 1000) // cap at 0.1 at the bottom
                min_display = dc_fixpt_from_fraction(1, 10);
        if (fs_params->max_display < 100) // cap at 100 at the top