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From:   Jeff Xu <jeffxu@chromium.org>
Date:   Tue, 13 Jun 2023 08:26:26 -0700
Message-ID: <CABi2SkXw6ZD-M1ZrcXNL7abtM=RzQXv716PPM_k=1Tay=5rUFA@mail.gmail.com>
Subject: Re: inconsistence in mprotect_fixup mlock_fixup madvise_update_vma
To:     linux-mm@kvack.org, linux-hardening@vger.kernel.org,
        Liam.Howlett@oracle.com, peterx@redhat.com,
        zhangpeng.00@bytedance.com, akpm@linux-foundation.org,
        koct9i@gmail.com, david@redhat.com, ak@linux.intel.com,
        hughd@google.com, emunson@akamai.com, rppt@linux.ibm.com,
        aarcange@redhat.com, linux-kernel@vger.kernel.org
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+ more ppl to the list.

On Mon, Jun 12, 2023 at 6:04=E2=80=AFPM Jeff Xu <jeffxu@chromium.org> wrote=
:
>
> Hello,
>
> There seems to be inconsistency in different VMA fixup
> implementations, for example:
> mlock_fixup will skip VMA that is hugettlb, etc, but those checks do
> not exist in mprotect_fixup and madvise_update_vma. Wouldn't this be a
> problem? the merge/split skipped by mlock_fixup, might get acted on in
> the madvice/mprotect case.
>
> mlock_fixup currently check for
> if (newflags =3D=3D oldflags || (oldflags & VM_SPECIAL) ||
> is_vm_hugetlb_page(vma) || vma =3D=3D get_gate_vma(current->mm) ||
> vma_is_dax(vma) || vma_is_secretmem(vma))
>
> Should there be a common function to handle VMA merge/split ?
>
> Best
> -Jeff