linux-kernel - Re: [PATCH 2/5] coredump: Snapshot the vmas in do

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Message-ID: <CAG48ez0uV87=myLX1X1KjQ_8q_Sgg1QZBG6vpdkGLWj==EAUBw@mail.gmail.com>
Date:   Tue, 1 Feb 2022 19:32:58 +0100
From:   Jann Horn <jannh@...gle.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Matthew Wilcox <willy@...radead.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Denys Vlasenko <vda.linux@...glemail.com>,
        Kees Cook <keescook@...omium.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Liam R . Howlett" <liam.howlett@...cle.com>
Subject: Re: [PATCH 2/5] coredump: Snapshot the vmas in do_coredump

On Mon, Jan 31, 2022 at 7:46 PM Eric W. Biederman <ebiederm@...ssion.com> wrote:
> Move the call of dump_vma_snapshot and kvfree(vma_meta) out of the
> individual coredump routines into do_coredump itself.  This makes
> the code less error prone and easier to maintain.
>
> Make the vma snapshot available to the coredump routines
> in struct coredump_params.  This makes it easier to
> change and update what is captures in the vma snapshot
> and will be needed for fixing fill_file_notes.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>

Reviewed-by: Jann Horn <jannh@...gle.com>

>         for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
>                         vma = next_vma(vma, gate_vma), i++) {
> -               struct core_vma_metadata *m = (*vma_meta) + i;
> +               struct core_vma_metadata *m = cprm->vma_meta + i;
>
>                 m->start = vma->vm_start;
>                 m->end = vma->vm_end;
>                 m->flags = vma->vm_flags;
>                 m->dump_size = vma_dump_size(vma, cprm->mm_flags);
>
> -               vma_data_size += m->dump_size;
> +               cprm->vma_data_size += m->dump_size;

FYI, this part is probably going to cause a merge conflict with the
fix https://www.ozlabs.org/~akpm/mmotm/broken-out/coredump-also-dump-first-pages-of-non-executable-elf-libraries.patch
in akpm's tree. I don't know what the right way to handle that is,
just thought I'd point it out.