From: Brad Spengler <[email protected]>
The kref_put() call uses (void *)kvfree as the release callback, which
is incorrect. kref_put() expects a function with signature
void (*release)(struct kref *), but kvfree has signature
void (*)(const void *). Calling through an incompatible function pointer
is undefined behavior.
The code only worked by accident because ref_count is the first member
of vmw_bo_dirty, making the kref pointer equal to the struct pointer.
Fix this by adding a proper release callback that uses container_of()
to retrieve the containing structure before freeing.
Fixes: c1962742ffff ("drm/vmwgfx: Use kref in vmw_bo_dirty")
Signed-off-by: Brad Spengler <[email protected]>
Signed-off-by: Zack Rusin <[email protected]>
Cc: Ian Forbes <[email protected]>
---
drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c
b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c
index fd4e76486f2d..45561bc1c9ef 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c
@@ -260,6 +260,13 @@ int vmw_bo_dirty_add(struct vmw_bo *vbo)
return ret;
}
+static void vmw_bo_dirty_free(struct kref *kref)
+{
+ struct vmw_bo_dirty *dirty = container_of(kref, struct vmw_bo_dirty,
ref_count);
+
+ kvfree(dirty);
+}
+
/**
* vmw_bo_dirty_release - Release a dirty-tracking user from a buffer object
* @vbo: The buffer object
@@ -274,7 +281,7 @@ void vmw_bo_dirty_release(struct vmw_bo *vbo)
{
struct vmw_bo_dirty *dirty = vbo->dirty;
- if (dirty && kref_put(&dirty->ref_count, (void *)kvfree))
+ if (dirty && kref_put(&dirty->ref_count, vmw_bo_dirty_free))
vbo->dirty = NULL;
}
--
2.48.1
