drm: Use drm_mode_init() for on-stack modes

Initialize on-stack modes with drm_mode_init() to guarantee
no stack garbage in the list head, or that we aren't copying
over another mode's list head.

Based on the following cocci script, with manual fixups:
@decl@
identifier M;
expression E;
@@
- struct drm_display_mode M = E;
+ struct drm_display_mode M;

@@
identifier decl.M;
expression decl.E;
statement S, S1;
@@
struct drm_display_mode M;
... when != S
+ drm_mode_init(&M, &E);
+
S1

@@
expression decl.E;
@@
- &*E
+ E

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220218100403.7028-22-ville.syrjala@linux.intel.com
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>

3 files changed, 13 insertions, 7 deletions

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index bff917531f33..a34aa009725f 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -297,8 +297,8 @@ bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
 		return false;
 	}
 
-	saved_mode = crtc->mode;
-	saved_hwmode = crtc->hwmode;
+	drm_mode_init(&saved_mode, &crtc->mode);
+	drm_mode_init(&saved_hwmode, &crtc->hwmode);
 	saved_x = crtc->x;
 	saved_y = crtc->y;
 
@@ -411,8 +411,8 @@ done:
 	drm_mode_destroy(dev, adjusted_mode);
 	if (!ret) {
 		crtc->enabled = saved_enabled;
-		crtc->mode = saved_mode;
-		crtc->hwmode = saved_hwmode;
+		drm_mode_copy(&crtc->mode, &saved_mode);
+		drm_mode_copy(&crtc->hwmode, &saved_hwmode);
 		crtc->x = saved_x;
 		crtc->y = saved_y;
 	}
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 04e818ecd662..dbca588474c3 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3551,9 +3551,11 @@ static u8 drm_match_cea_mode_clock_tolerance(const struct drm_display_mode *to_m
 		match_flags |= DRM_MODE_MATCH_ASPECT_RATIO;
 
 	for (vic = 1; vic < cea_num_vics(); vic = cea_next_vic(vic)) {
-		struct drm_display_mode cea_mode = *cea_mode_for_vic(vic);
+		struct drm_display_mode cea_mode;
 		unsigned int clock1, clock2;
 
+		drm_mode_init(&cea_mode, cea_mode_for_vic(vic));
+
 		/* Check both 60Hz and 59.94Hz */
 		clock1 = cea_mode.clock;
 		clock2 = cea_mode_alternate_clock(&cea_mode);
@@ -3590,9 +3592,11 @@ u8 drm_match_cea_mode(const struct drm_display_mode *to_match)
 		match_flags |= DRM_MODE_MATCH_ASPECT_RATIO;
 
 	for (vic = 1; vic < cea_num_vics(); vic = cea_next_vic(vic)) {
-		struct drm_display_mode cea_mode = *cea_mode_for_vic(vic);
+		struct drm_display_mode cea_mode;
 		unsigned int clock1, clock2;
 
+		drm_mode_init(&cea_mode, cea_mode_for_vic(vic));
+
 		/* Check both 60Hz and 59.94Hz */
 		clock1 = cea_mode.clock;
 		clock2 = cea_mode_alternate_clock(&cea_mode);
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 6e7e10f16ec0..e699950cc34d 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -837,7 +837,9 @@ EXPORT_SYMBOL(drm_mode_vrefresh);
 void drm_mode_get_hv_timing(const struct drm_display_mode *mode,
 			    int *hdisplay, int *vdisplay)
 {
-	struct drm_display_mode adjusted = *mode;
+	struct drm_display_mode adjusted;
+
+	drm_mode_init(&adjusted, mode);
 
 	drm_mode_set_crtcinfo(&adjusted, CRTC_STEREO_DOUBLE_ONLY);
 	*hdisplay = adjusted.crtc_hdisplay;