drm/mediatek: Check CRTC state before freeing

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>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20260707150528.2270739-1-ruoyuw560@gmail.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

diff --git a/drivers/gpu/drm/mediatek/mtk_crtc.c b/drivers/gpu/drm/mediatek/mtk_crtc.c
index 8e552cdc3b53b97303a1f642152d06b11899e9cf..97e3ff412e6ee5abb1dff4d118fb65a6e2336101 100644 (file)
--- 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);