[PATCH] drm/syncobj: Fix syncobj leak in drm_syncobj_eventfd_ioctl

["T.J. Mercier" <tjmercier@xxxxxxxxxx>]

A syncobj reference is taken in drm_syncobj_find, but not released if
eventfd_ctx_fdget or kzalloc fails. Put the reference in these error
paths.

Reported-by: Xingyu Jin <xingyuj@xxxxxxxxxx>
Fixes: c7a472297169 ("drm/syncobj: add IOCTL to register an eventfd")
Signed-off-by: T.J. Mercier <tjmercier@xxxxxxxxxx>
---
 drivers/gpu/drm/drm_syncobj.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index a0e94217b511..4fcfc0b9b386 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -1464,6 +1464,7 @@ drm_syncobj_eventfd_ioctl(struct drm_device *dev, void *data,
 	struct drm_syncobj *syncobj;
 	struct eventfd_ctx *ev_fd_ctx;
 	struct syncobj_eventfd_entry *entry;
+	int ret;
 
 	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
 		return -EOPNOTSUPP;
@@ -1479,13 +1480,15 @@ drm_syncobj_eventfd_ioctl(struct drm_device *dev, void *data,
 		return -ENOENT;
 
 	ev_fd_ctx = eventfd_ctx_fdget(args->fd);
-	if (IS_ERR(ev_fd_ctx))
-		return PTR_ERR(ev_fd_ctx);
+	if (IS_ERR(ev_fd_ctx)) {
+		ret = PTR_ERR(ev_fd_ctx);
+		goto err_fdget;
+	}
 
 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 	if (!entry) {
-		eventfd_ctx_put(ev_fd_ctx);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto err_kzalloc;
 	}
 	entry->syncobj = syncobj;
 	entry->ev_fd_ctx = ev_fd_ctx;
@@ -1496,6 +1499,12 @@ drm_syncobj_eventfd_ioctl(struct drm_device *dev, void *data,
 	drm_syncobj_put(syncobj);
 
 	return 0;
+
+err_kzalloc:
+	eventfd_ctx_put(ev_fd_ctx);
+err_fdget:
+	drm_syncobj_put(syncobj);
+	return ret;
 }
 
 int
-- 
2.46.0.598.g6f2099f65c-goog