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    SubjectRe: [PATCH] Restrict stack space reservation to rlimit
    Date
    > On Mon, Feb 8, 2010 at 2:05 PM, KOSAKI Motohiro
    > <kosaki.motohiro@jp.fujitsu.com> wrote:
    > >> --- linux-2.6-ozlabs.orig/fs/exec.c
    > >> +++ linux-2.6-ozlabs/fs/exec.c
    > >> @@ -627,10 +627,13 @@ int setup_arg_pages(struct linux_binprm
    > >>                       goto out_unlock;
    > >>       }
    > >>
    > >> +     stack_base = min(EXTRA_STACK_VM_PAGES * PAGE_SIZE,
    > >> +                      current->signal->rlim[RLIMIT_STACK].rlim_cur -
    > >> +                        PAGE_SIZE);
    > >
    > > This line is a bit unclear why "- PAGE_SIZE" is necessary.
    > > personally, I like following likes explicit comments.
    > >
    > >        stack_expand = EXTRA_STACK_VM_PAGES * PAGE_SIZE;
    > >        stack_lim = ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur);
    > >
    > >        /* Initial stack must not cause stack overflow. */
    > >        if (stack_expand + PAGE_SIZE > stack_lim)
    > >                stack_expand = stack_lim - PAGE_SIZE;
    > >
    > > note: accessing rlim_cur require ACCESS_ONCE.
    > >
    > >
    > > Thought?
    >
    > It's better to use the helper function: rlimit().

    AFAIK, stable tree doesn't have rlimit(). but yes, making two patch
    (for mainline and for stable) is good opinion.



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