From: Sinclair Yeh <s...@vmware.com>

When vmw_gb_surface_define_ioctl() is called with an existing buffer,
we end up returning an uninitialized variable in the backup_handle.

The fix is to first initialize backup_handle to 0 just to be sure, and
second, when a user-provided buffer is found, we will use the
req->buffer_handle as the backup_handle.

Cc: <sta...@vger.kernel.org>
Reported-by: Murray McAllister <murray.mcallis...@insomniasec.com>
Signed-off-by: Sinclair Yeh <s...@vmware.com>
Reviewed-by: Deepak Rawat <dra...@vmware.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c 
b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
index baf03d4..834bb10 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -1274,7 +1274,7 @@ int vmw_gb_surface_define_ioctl(struct drm_device *dev, 
void *data,
        struct ttm_object_file *tfile = vmw_fpriv(file_priv)->tfile;
        int ret;
        uint32_t size;
-       uint32_t backup_handle;
+       uint32_t backup_handle = 0;
 
        if (req->multisample_count != 0)
                return -EINVAL;
@@ -1317,12 +1317,16 @@ int vmw_gb_surface_define_ioctl(struct drm_device *dev, 
void *data,
                ret = vmw_user_dmabuf_lookup(tfile, req->buffer_handle,
                                             &res->backup,
                                             &user_srf->backup_base);
-               if (ret == 0 && res->backup->base.num_pages * PAGE_SIZE <
-                   res->backup_size) {
-                       DRM_ERROR("Surface backup buffer is too small.\n");
-                       vmw_dmabuf_unreference(&res->backup);
-                       ret = -EINVAL;
-                       goto out_unlock;
+               if (ret == 0) {
+                       if (res->backup->base.num_pages * PAGE_SIZE <
+                           res->backup_size) {
+                               DRM_ERROR("Surface backup buffer is too 
small.\n");
+                               vmw_dmabuf_unreference(&res->backup);
+                               ret = -EINVAL;
+                               goto out_unlock;
+                       } else {
+                               backup_handle = req->buffer_handle;
+                       }
                }
        } else if (req->drm_surface_flags & drm_vmw_surface_flag_create_buffer)
                ret = vmw_user_dmabuf_alloc(dev_priv, tfile,
-- 
2.7.4

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