On Thu, 16 Jan 2025 10:50:05 +0800 Liu Ye <liuye@xxxxxxxxxx> wrote: > Add VM_WARN_ON to prevent 'adjust' from accessing NULL pointers > when 'adjust' is NULL and 'expanded' is false or 'adj_start' is > not zero. > > ... > > --- a/mm/vma.c > +++ b/mm/vma.c > @@ -641,6 +641,7 @@ static int commit_merge(struct vma_merge_struct *vmg, > > init_multi_vma_prep(&vp, vmg->vma, adjust, remove, remove2); > > + VM_WARN_ON(!adjust && (!expanded || adj_start)); > VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma && > vp.anon_vma != adjust->anon_vma); > This won't prevent a null deref. It will emit a warning which duplicates all the information which we're about to emit from the oops handler. Are there any reports of an oops from a NULL deref of `adjust'?
