[PATCH 5.15 496/917] drm/msm: Fix potential NULL dereference in DPU SSPP

[Greg Kroah-Hartman]

From: Jessica Zhang <jesszhan@xxxxxxxxxxxxxx>

[ Upstream commit 8bf71a5719b6cc5b6ba358096081e5d50ea23ab6 ]

Move initialization of sblk in _sspp_subblk_offset() after NULL check to
avoid potential NULL pointer dereference.

Fixes: 25fdd5933e4c ("drm/msm: Add SDM845 DPU support")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Jessica Zhang <jesszhan@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211020175733.3379-1-jesszhan@xxxxxxxxxxxxxx
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c
index 69eed79324865..f9460672176aa 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c
@@ -138,11 +138,13 @@ static int _sspp_subblk_offset(struct dpu_hw_pipe *ctx,
 		u32 *idx)
 {
 	int rc = 0;
-	const struct dpu_sspp_sub_blks *sblk = ctx->cap->sblk;
+	const struct dpu_sspp_sub_blks *sblk;
 
-	if (!ctx)
+	if (!ctx || !ctx->cap || !ctx->cap->sblk)
 		return -EINVAL;
 
+	sblk = ctx->cap->sblk;
+
 	switch (s_id) {
 	case DPU_SSPP_SRC:
 		*idx = sblk->src_blk.base;
@@ -419,7 +421,7 @@ static void _dpu_hw_sspp_setup_scaler3(struct dpu_hw_pipe *ctx,
 
 	(void)pe;
 	if (_sspp_subblk_offset(ctx, DPU_SSPP_SCALER_QSEED3, &idx) || !sspp
-		|| !scaler3_cfg || !ctx || !ctx->cap || !ctx->cap->sblk)
+		|| !scaler3_cfg)
 		return;
 
 	dpu_hw_setup_scaler3(&ctx->hw, scaler3_cfg, idx,
-- 
2.33.0