[PATCH] drm/msm/dpu: reorder pointer operations after sanity checks to avoid NULL deref

[Qasim Ijaz]

_dpu_encoder_trigger_start dereferences "struct dpu_encoder_phys *phys" 
before the sanity checks which can lead to a NULL pointer dereference if 
phys is NULL. 

Fix this by reordering the dereference after the sanity checks.

Signed-off-by: Qasim Ijaz <qasde...@gmail.com>
Fixes: 8144d17a81d9 ("drm/msm/dpu: Skip trigger flush and start for CWB")
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c 
b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index 0eed93a4d056..ba8b2a163232 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -1667,8 +1667,6 @@ static void _dpu_encoder_trigger_flush(struct drm_encoder 
*drm_enc,
  */
 static void _dpu_encoder_trigger_start(struct dpu_encoder_phys *phys)
 {
-       struct dpu_encoder_virt *dpu_enc = to_dpu_encoder_virt(phys->parent);
-
        if (!phys) {
                DPU_ERROR("invalid argument(s)\n");
                return;
@@ -1679,6 +1677,8 @@ static void _dpu_encoder_trigger_start(struct 
dpu_encoder_phys *phys)
                return;
        }
 
+       struct dpu_encoder_virt *dpu_enc = to_dpu_encoder_virt(phys->parent);
+
        if (phys->parent->encoder_type == DRM_MODE_ENCODER_VIRTUAL &&
            dpu_enc->cwb_mask) {
                DPU_DEBUG("encoder %d CWB enabled, skipping\n", 
DRMID(phys->parent));
-- 
2.39.5