The commit "drm/vmwgfx: Fix up user_dmabuf refcounting", while fixing a kernel crash introduced a NULL pointer dereference on older hardware. Fix this.

Cc: stable@vger.kernel.org Signed-off-by: Thomas Hellstrom thellstrom@vmware.com Reviewed-by: Sinclair Yeh syeh@vmware.com Reviewed-by: Brian Paul brianp@vmware.com --- drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c index 64b5040..03f63c7 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c @@ -657,7 +657,8 @@ static void vmw_user_surface_base_release(struct ttm_base_object **p_base) struct vmw_resource *res = &user_srf->srf.res;

*p_base = NULL; - ttm_base_object_unref(&user_srf->backup_base); + if (user_srf->backup_base) + ttm_base_object_unref(&user_srf->backup_base); vmw_resource_unreference(&res); }