drm/shmem-helper: Remove errant put in error path

drm_gem_shmem_mmap() doesn't own this reference, resulting in the GEM
object getting prematurely freed leading to a later use-after-free.

Link: https://syzkaller.appspot.com/bug?extid=c8ae65286134dd1b800d
Reported-by: syzbot+c8ae65286134dd1b800d@syzkaller.appspotmail.com
Fixes: 2194a63a818d ("drm: Add library for shmem backed GEM objects")
Cc: stable@vger.kernel.org
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221130185748.357410-2-robdclark@gmail.com

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 35138f8..3b7b713 100644 (file)
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -622,10 +622,8 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct
        }
 
        ret = drm_gem_shmem_get_pages(shmem);
-       if (ret) {
-               drm_gem_vm_close(vma);
+       if (ret)
                return ret;
-       }
 
        vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);