dma-buf: fix an error pointer vs NULL bug

Smatch detected potential error pointer dereference.

    drivers/gpu/drm/drm_syncobj.c:888 drm_syncobj_transfer_to_timeline()
    error: 'fence' dereferencing possible ERR_PTR()

The error pointer comes from dma_fence_allocate_private_stub().  One
caller expected error pointers and one expected NULL pointers.  Change
it to return NULL and update the caller which expected error pointers,
drm_syncobj_assign_null_handle(), to check for NULL instead.

Fixes: f781f661e8c9 ("dma-buf: keep the signaling time of merged fences v3")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/b09f1996-3838-4fa2-9193-832b68262e43@moroto.mountain

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index ad076f208760f94ac3beeef115ff676b90bf97a4..8aa8f8cb7071efcce29b62cf5ac3bd96c7308056 100644 (file)
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -160,7 +160,7 @@ struct dma_fence *dma_fence_allocate_private_stub(ktime_t timestamp)
 
        fence = kzalloc(sizeof(*fence), GFP_KERNEL);
        if (fence == NULL)
-               return ERR_PTR(-ENOMEM);
+               return NULL;
 
        dma_fence_init(fence,
                       &dma_fence_stub_ops,

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 04589a35eb09d79c4db24ecacf2c62f1840020bf..e592c5da70ceec781240572812a15b40a47eddf5 100644 (file)
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -355,8 +355,8 @@ static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
 {
        struct dma_fence *fence = dma_fence_allocate_private_stub(ktime_get());
 
-       if (IS_ERR(fence))
-               return PTR_ERR(fence);
+       if (!fence)
+               return -ENOMEM;
 
        drm_syncobj_replace_fence(syncobj, fence);
        dma_fence_put(fence);