[PATCH] drm/prime: Ensure mmap offset is initialized

[Rob Clark <robdclark@gmail.com>]

From: Rob Clark <robdclark@chromium.org>

If a GEM object is allocated, and then exported as a dma-buf fd which is
mmap'd before or without the GEM buffer being directly mmap'd, the
vma_node could be unitialized.  This leads to a situation where the CPU
mapping is not correctly torn down in drm_vma_node_unmap().

Fixes: e5516553999f ("drm: call drm_gem_object_funcs.mmap with fake offset")
Signed-off-by: Rob Clark <robdclark@chromium.org>
---
Note, it's possible the issue existed in some related form prior to the
commit tagged with Fixes.

 drivers/gpu/drm/drm_prime.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index e3f09f18110c..849eea154dfc 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -716,6 +716,11 @@ int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
 	struct file *fil;
 	int ret;
 
+	/* Ensure that the vma_node is initialized: */
+	ret = drm_gem_create_mmap_offset(obj);
+	if (ret)
+		return ret;
+
 	/* Add the fake offset */
 	vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
 
-- 
2.35.3