[PATCH] drm/mediatek: Check CRTC state before freeing

[Ruoyu Wang <ruoyuw560@gmail.com>]

mtk_crtc_reset() destroys the current CRTC state only when crtc->state
is non-NULL, but it always converts crtc->state to struct mtk_crtc_state
and passes the result to kfree().

When reset is called without an existing state, container_of(NULL, ...)
does not produce NULL. Keep the mtk state free in the same crtc->state
guard as the helper state destruction.

This issue was found by a static analysis checker and confirmed by
manual source review.

Fixes: 2d267b81898e ("drm/mtk: Use __drm_atomic_helper_crtc_reset")
Signed-off-by: Ruoyu Wang <ruoyuw560@gmail.com>
---
 drivers/gpu/drm/mediatek/mtk_crtc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_crtc.c b/drivers/gpu/drm/mediatek/mtk_crtc.c
index 8e552cdc3b53b..97e3ff412e6ee 100644
--- a/drivers/gpu/drm/mediatek/mtk_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_crtc.c
@@ -154,10 +154,10 @@ static void mtk_crtc_reset(struct drm_crtc *crtc)
 {
 	struct mtk_crtc_state *state;
 
-	if (crtc->state)
+	if (crtc->state) {
 		__drm_atomic_helper_crtc_destroy_state(crtc->state);
-
-	kfree(to_mtk_crtc_state(crtc->state));
+		kfree(to_mtk_crtc_state(crtc->state));
+	}
 	crtc->state = NULL;
 
 	state = kzalloc_obj(*state);
-- 
2.51.0