drm/msm/dpu: invalid parameter check in dpu_setup_dspp_pcc

stable inclusion
from stable-v5.10.96
commit 93a6e920d8ccb4df846c03b6e72f7e08843d294c
bugzilla: https://gitee.com/openeuler/kernel/issues/I55NWB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=93a6e920d8ccb4df846c03b6e72f7e08843d294c

--------------------------------

[ Upstream commit 170b2223 ]

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: 4259ff7a ("drm/msm/dpu: add support for pcc color block in dpu driver")
Addresses-Coverity-ID: 1493866 ("Null pointer dereference")
Signed-off-by: NJosé Expósito <jose.exposito89@gmail.com>
Link: https://lore.kernel.org/r/20220109192431.135949-1-jose.exposito89@gmail.comSigned-off-by: NDmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYu Liao <liaoyu15@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

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;
 	}