virtio-mmio: fix memory leak of vm_dev

With the recent removal of vm_dev from devres its memory is only freed
via the callback virtio_mmio_release_dev. However, this only takes
effect after device_add is called by register_virtio_device. Until then
it's an unmanaged resource and must be explicitly freed on error exit.

This bug was discovered and resolved using Coverity Static Analysis
Security Testing (SAST) by Synopsys, Inc.

Cc: stable@vger.kernel.org
Fixes: 55c91fed ("virtio-mmio: don't break lifecycle of vm_dev")
Signed-off-by: Maximilian Heyne <mheyne@amazon.de>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>

Message-Id: <20230911090328.40538-1-mheyne@amazon.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

drivers/virtio/virtio_mmio.c

@@ -631,14 +631,17 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 	spin_lock_init(&vm_dev->lock);
 
 	vm_dev->base = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(vm_dev->base))
-		return PTR_ERR(vm_dev->base);
+	if (IS_ERR(vm_dev->base)) {
+		rc = PTR_ERR(vm_dev->base);
+		goto free_vm_dev;
+	}
 
 	/* Check magic value */
 	magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
 	if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)) {
 		dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
-		return -ENODEV;
+		rc = -ENODEV;
+		goto free_vm_dev;
 	}
 
 	/* Check device version */
@@ -646,7 +649,8 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 	if (vm_dev->version < 1 || vm_dev->version > 2) {
 		dev_err(&pdev->dev, "Version %ld not supported!\n",
 				vm_dev->version);
-		return -ENXIO;
+		rc = -ENXIO;
+		goto free_vm_dev;
 	}
 
 	vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
@@ -655,7 +659,8 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 		 * virtio-mmio device with an ID 0 is a (dummy) placeholder
 		 * with no function. End probing now with no error reported.
 		 */
-		return -ENODEV;
+		rc = -ENODEV;
+		goto free_vm_dev;
 	}
 	vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
 
@@ -685,6 +690,10 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 		put_device(&vm_dev->vdev.dev);
 
 	return rc;
+
+free_vm_dev:
+	kfree(vm_dev);
+	return rc;
 }
 
 static int virtio_mmio_remove(struct platform_device *pdev)