iommu/msm: Add a check for the return of kzalloc()

kzalloc() is a memory allocation function which can return NULL when
some internal memory errors happen. So it is better to check it to
prevent potential wrong memory access.

Besides, to propagate the error to the caller, the type of
insert_iommu_master() is changed to `int`. Several instructions related
to it are also updated.

Signed-off-by: Xiaoke Wang <xkernel.wang@foxmail.com>
Link: https://lore.kernel.org/r/tencent_EDB94B1C7E14B4E1974A66FF4D2029CC6D08@qq.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/msm_iommu.c

@@ -583,7 +583,7 @@ static void print_ctx_regs(void __iomem *base, int ctx)
 	       GET_SCTLR(base, ctx), GET_ACTLR(base, ctx));
 }
 
-static void insert_iommu_master(struct device *dev,
+static int insert_iommu_master(struct device *dev,
 				struct msm_iommu_dev **iommu,
 				struct of_phandle_args *spec)
 {
@@ -592,6 +592,10 @@ static void insert_iommu_master(struct device *dev,
 
 	if (list_empty(&(*iommu)->ctx_list)) {
 		master = kzalloc(sizeof(*master), GFP_ATOMIC);
+		if (!master) {
+			dev_err(dev, "Failed to allocate iommu_master\n");
+			return -ENOMEM;
+		}
 		master->of_node = dev->of_node;
 		list_add(&master->list, &(*iommu)->ctx_list);
 		dev_iommu_priv_set(dev, master);
@@ -601,10 +605,11 @@ static void insert_iommu_master(struct device *dev,
 		if (master->mids[sid] == spec->args[0]) {
 			dev_warn(dev, "Stream ID 0x%hx repeated; ignoring\n",
 				 sid);
-			return;
+			return 0;
 		}
 
 	master->mids[master->num_mids++] = spec->args[0];
+	return 0;
 }
 
 static int qcom_iommu_of_xlate(struct device *dev,
@@ -624,7 +629,7 @@ static int qcom_iommu_of_xlate(struct device *dev,
 		goto fail;
 	}
 
-	insert_iommu_master(dev, &iommu, spec);
+	ret = insert_iommu_master(dev, &iommu, spec);
 fail:
 	spin_unlock_irqrestore(&msm_iommu_lock, flags);