[PATCH] drm/virtio: fix vbuf->objs double-free, fence NULL deref, and sgt error path

[Hui Peng <benquike@gmail.com>]

Fix three error-handling bugs in drivers/gpu/drm/virtio/:

1. In virtio_gpu_dequeue_ctrl_func() and vbuf cleanup (virtgpu_vq.c),
   clear entry->objs after freeing so objects are not double-released,
   and fix the vmalloc_to_sgt() error path.
2. In virtio_gpu_cleanup_submit() (virtgpu_submit.c), cancel and free
   out_fence->e when submit fails before drm_event_reserve_init()
   completes.

Fixes: dc5698e80cf7 ("Add virtio gpu driver.")
Assisted-by: LLM
Signed-off-by: Hui Peng <benquike@gmail.com>
---
diff --git a/drivers/gpu/drm/virtio/virtgpu_submit.c b/drivers/gpu/drm/virtio/virtgpu_submit.c
index 32cb1e4aa425..84aeea58c700 100644
--- a/drivers/gpu/drm/virtio/virtgpu_submit.c
+++ b/drivers/gpu/drm/virtio/virtgpu_submit.c
@@ -343,8 +343,14 @@ static void virtio_gpu_cleanup_submit(struct virtio_gpu_submit *submit)
 	if (submit->out_fence_fd >= 0)
 		put_unused_fd(submit->out_fence_fd);
 
-	if (submit->out_fence)
+	if (submit->out_fence) {
+		if (submit->out_fence->e && !submit->out_fence->f.seqno) {
+			drm_event_cancel_free(submit->vgdev->ddev,
+					      &submit->out_fence->e->base);
+			submit->out_fence->e = NULL;
+		}
 		dma_fence_put(&submit->out_fence->f);
+	}
 
 	if (submit->sync_file)
 		fput(submit->sync_file->file);
@@ -415,6 +421,9 @@ static int virtio_gpu_init_submit(struct virtio_gpu_submit *submit,
 	if (err)
 		return err;
 
+	if (!exbuf->size)
+		return -EINVAL;
+
 	submit->buf = vmemdup_user(u64_to_user_ptr(exbuf->command), exbuf->size);
 	if (IS_ERR(submit->buf))
 		return PTR_ERR(submit->buf);
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index c02c03c10d92..115156a680bc 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -202,6 +202,10 @@ static void *virtio_gpu_alloc_cmd_cb(struct virtio_gpu_device *vgdev,
 static void free_vbuf(struct virtio_gpu_device *vgdev,
 		      struct virtio_gpu_vbuffer *vbuf)
 {
+	if (vbuf->objs) {
+		virtio_gpu_array_put_free_delayed(vgdev, vbuf->objs);
+		vbuf->objs = NULL;
+	}
 	if (vbuf->resp_size > MAX_INLINE_RESP_SIZE)
 		kfree(vbuf->resp_buf);
 	kvfree(vbuf->data_buf);
@@ -282,8 +286,6 @@ void virtio_gpu_dequeue_ctrl_func(struct work_struct *work)
 	wake_up(&vgdev->ctrlq.ack_queue);
 
 	list_for_each_entry_safe(entry, tmp, &reclaim_list, list) {
-		if (entry->objs)
-			virtio_gpu_array_put_free_delayed(vgdev, entry->objs);
 		list_del(&entry->list);
 		free_vbuf(vgdev, entry);
 	}
@@ -517,6 +519,7 @@ static int virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
 			if (!sgt) {
 				if (fence && vbuf->objs)
 					virtio_gpu_array_unlock_resv(vbuf->objs);
+				free_vbuf(vgdev, vbuf);
 				return -ENOMEM;
 			}
 
@@ -1409,8 +1412,7 @@ virtio_gpu_cmd_resource_assign_uuid(struct virtio_gpu_device *vgdev,
 	cmd_p->resource_id = cpu_to_le32(bo->hw_res_handle);
 
 	vbuf->objs = objs;
-	virtio_gpu_queue_ctrl_buffer(vgdev, vbuf);
-	return 0;
+	return virtio_gpu_queue_ctrl_buffer(vgdev, vbuf);
 }
 
 static void virtio_gpu_cmd_resource_map_cb(struct virtio_gpu_device *vgdev,