drm/msm: Fix submit error-path leaks

For errors after msm_submitqueue_get(), we need to drop the submitqueue
reference.  Additionally after get_unused_fd() we need to drop the fd.
The ordering for dropping the queue lock and put_unused_fd() is not
important, so just move this all into out_post_unlock.

v2: Only drop queue ref if submit doesn't take it
v3: Fix unitialized submit ref in error path
v4: IS_ERR_OR_NULL()

Reported-by: pinkperfect2021@gmail.com
Fixes: f0de40a1 drm/msm: ("Reorder lock vs submit alloc")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/536073/
Link: https://lore.kernel.org/r/20230509203041.440619-1-robdclark@gmail.com

drivers/gpu/drm/msm/msm_gem_submit.c

@@ -722,7 +722,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 	struct msm_drm_private *priv = dev->dev_private;
 	struct drm_msm_gem_submit *args = data;
 	struct msm_file_private *ctx = file->driver_priv;
-	struct msm_gem_submit *submit;
+	struct msm_gem_submit *submit = NULL;
 	struct msm_gpu *gpu = priv->gpu;
 	struct msm_gpu_submitqueue *queue;
 	struct msm_ringbuffer *ring;
@@ -769,13 +769,15 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 		out_fence_fd = get_unused_fd_flags(O_CLOEXEC);
 		if (out_fence_fd < 0) {
 			ret = out_fence_fd;
-			return ret;
+			goto out_post_unlock;
 		}
 	}
 
 	submit = submit_create(dev, gpu, queue, args->nr_bos, args->nr_cmds);
-	if (IS_ERR(submit))
-		return PTR_ERR(submit);
+	if (IS_ERR(submit)) {
+		ret = PTR_ERR(submit);
+		goto out_post_unlock;
+	}
 
 	trace_msm_gpu_submit(pid_nr(submit->pid), ring->id, submit->ident,
 		args->nr_bos, args->nr_cmds);
@@ -962,11 +964,20 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 	if (has_ww_ticket)
 		ww_acquire_fini(&submit->ticket);
 out_unlock:
-	if (ret && (out_fence_fd >= 0))
-		put_unused_fd(out_fence_fd);
 	mutex_unlock(&queue->lock);
 out_post_unlock:
-	msm_gem_submit_put(submit);
+	if (ret && (out_fence_fd >= 0))
+		put_unused_fd(out_fence_fd);
+
+	if (!IS_ERR_OR_NULL(submit)) {
+		msm_gem_submit_put(submit);
+	} else {
+		/*
+		 * If the submit hasn't yet taken ownership of the queue
+		 * then we need to drop the reference ourself:
+		 */
+		msm_submitqueue_put(queue);
+	}
 	if (!IS_ERR_OR_NULL(post_deps)) {
 		for (i = 0; i < args->nr_out_syncobjs; ++i) {
 			kfree(post_deps[i].chain);