linux-kernel - [PATCH] drm/msm/dpu: invalid parameter check in dpu_setup_dspp

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Date:   Sun,  9 Jan 2022 20:24:31 +0100
From:   José Expósito <jose.exposito89@...il.com>
To:     kalyan_t@...eaurora.org
Cc:     robdclark@...il.com, sean@...rly.run, airlied@...ux.ie,
        daniel@...ll.ch, dmitry.baryshkov@...aro.org,
        abhinavk@...eaurora.org, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        José Expósito <jose.exposito89@...il.com>
Subject: [PATCH] drm/msm/dpu: invalid parameter check in dpu_setup_dspp_pcc

The function performs a check on the "ctx" input parameter, however, it
is used before the check.

Initialize the "base" variable after the sanity check to avoid a
possible NULL pointer dereference.

Fixes: 4259ff7ae509e ("drm/msm/dpu: add support for pcc color block in dpu driver")
Addresses-Coverity-ID: 1493866 ("Null pointer dereference")
Signed-off-by: José Expósito <jose.exposito89@...il.com>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.c
index a98e964c3b6f..355894a3b48c 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.c
@@ -26,9 +26,16 @@ static void dpu_setup_dspp_pcc(struct dpu_hw_dspp *ctx,
 		struct dpu_hw_pcc_cfg *cfg)
 {
 
-	u32 base = ctx->cap->sblk->pcc.base;
+	u32 base;
 
-	if (!ctx || !base) {
+	if (!ctx) {
+		DRM_ERROR("invalid ctx %pK\n", ctx);
+		return;
+	}
+
+	base = ctx->cap->sblk->pcc.base;
+
+	if (!base) {
 		DRM_ERROR("invalid ctx %pK pcc base 0x%x\n", ctx, base);
 		return;
 	}
-- 
2.25.1