Messages in this thread | | | Date | Thu, 24 Feb 2022 20:18:59 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 1/1] mm: fix use-after-free bug when mm->mmap is reused after being freed |
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On Tue, 15 Feb 2022 12:19:22 -0800 Suren Baghdasaryan <surenb@google.com> 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); > }
After the Maple tree patches, mm_struct.mmap doesn't exist. So I'll revert this fix as part of merging the maple-tree parts of linux-next. I'll be sending this fix to Linus this week.
All of which means that the thusly-resolved Maple tree patches might reintroduce this use-after-free bug.
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