From: Rob Clark <robdclark@xxxxxxxxxxxx> commit 24013314be6ee4ee456114a671e9fa3461323de8 upstream. 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@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 2194a63a818d ("drm: Add library for shmem backed GEM objects") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx> Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20221130185748.357410-2-robdclark@xxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/drm_gem_shmem_helper.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- 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_sh } 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);
