On Tue, Feb 15, 2022 at 12:37 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Tue, 15 Feb 2022 12:19:22 -0800 Suren Baghdasaryan <surenb@xxxxxxxxxx> wrote: > > > After exit_mmap frees all vmas in the mm, mm->mmap needs to be reset, > > otherwise it points to a vma that was freed and when reused leads to > > a use-after-free bug. > > > > ... > > > > --- a/mm/mmap.c > > +++ b/mm/mmap.c > > @@ -3186,6 +3186,7 @@ void exit_mmap(struct mm_struct *mm) > > vma = remove_vma(vma); > > cond_resched(); > > } > > + mm->mmap = NULL; > > mmap_write_unlock(mm); > > vm_unacct_memory(nr_accounted); > > } > > https://lore.kernel.org/all/00000000000072ef2c05d7f81950@xxxxxxxxxx/ > > It would be nice to have a Fixes: for this. Oh, right. Should be: Fixes: 64591e8605d6 ("mm: protect free_pgtables with mmap_lock write lock in exit_mmap") > > Is it specific to process_mrelease(), or should we backport further? The broken change is recent and was introduced in v5.17-rc1.
