[PATCH] drm/gem-atomic-helper: fix fence leak on dma_fence_chain_alloc() failure

[Chengyu Liu <lui2012qwq@gmail.com>]

In drm_gem_plane_helper_prepare_fb(), when both "new" (the plane's GEM
singleton fence) and "fence" (explicit or previous plane's) exist, they
are wrapped in a freshly allocated chain.  If dma_fence_chain_alloc()
fails, the error path runs before dma_fence_chain_init() adopts "new",
and error: only puts "fence" - leaking one fence reference per failure.

Put "new" in the allocation-failure branch.

Found by static analysis.

Signed-off-by: Chengyu Liu <lui2012qwq@gmail.com>
---
 drivers/gpu/drm/drm_gem_atomic_helper.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/drm_gem_atomic_helper.c b/drivers/gpu/drm/drm_gem_atomic_helper.c
index abef865c5f2c..1e484f26ab31 100644
--- a/drivers/gpu/drm/drm_gem_atomic_helper.c
+++ b/drivers/gpu/drm/drm_gem_atomic_helper.c
@@ -153,6 +153,7 @@
 		if (new && fence) {
 			struct dma_fence_chain *chain = dma_fence_chain_alloc();
 
 			if (!chain) {
+				dma_fence_put(new);
 				ret = -ENOMEM;
 				goto error;
 			}
-- 
2.25.1