lkml.org 
[lkml]   [2007]   [Oct]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] [RFC] brk randomization: compute RLIMIT_DATA properly (was Re: x86: randomize brk() and RLIMIT_DATA)
On Fri, 26 Oct 2007, Jiri Kosina wrote:
> On Fri, 26 Oct 2007, Hugh Dickins wrote:
>
> > > - if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim)
> > > + if (rlim < RLIM_INFINITY && brk - mm->start_data -
> > > + (mm->start_brk - mm->end_data) > rlim)
> > I find the order in that test mysterious.
>
> I agree that the order you proposed is easier to understand on the first
> sight.
>
>
> From: Jiri Kosina <jkosina@suse.cz>
>
> brk randomization: compute RLIMIT_DATA properly
>
> In cases of heap area placed at randomly-generated offset from
> mm->end_data (arch_randomize_brk()), we need to subtract the value of the
> offset for setrlimit(RLIMIT_DATA) to work properly -- otherwise we count
> the unoccupied memory between mm->end_data and mm->start_brk as occupied.
>
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Acked-by: Hugh Dickins <hugh@veritas.com>

>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index facc1a7..673ac7d 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -251,7 +251,8 @@ asmlinkage unsigned long sys_brk(unsigned long brk)
> * not page aligned -Ram Gupta
> */
> rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
> - if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim)
> + if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
> + (mm->end_data - mm->start_data) > rlim)
> goto out;
>
> newbrk = PAGE_ALIGN(brk);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-10-26 14:35    [W:0.075 / U:0.120 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site