Add error handling to check NULL input in
mtk_drm_crtc_dma_dev_get function.

While display path is not configured correctly, none of crtc is
established. So the caller of mtk_drm_crtc_dma_dev_get may pass
input parameter *crtc as NULL, Which may cause coredump when
we try to get the container of NULL pointer.

Stuart Lee (1):
  drm/mediatek: Fix access violation in mtk_drm_crtc_dma_dev_get

 drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

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2.18.0