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Message-ID: <Pine.LNX.4.64.0710261329450.27706@blonde.wat.veritas.com> Date: Fri, 26 Oct 2007 13:30:42 +0100 (BST) From: Hugh Dickins <hugh@...itas.com> To: Jiri Kosina <jikos@...os.cz> cc: Andrew Morton <akpm@...ux-foundation.org>, Sami Farin <safari-kernel@...ari.iki.fi>, Linux kernel Mailing List <linux-kernel@...r.kernel.org>, Jiri Kosina <jkosina@...e.cz>, Arjan van de Ven <arjan@...radead.org> Subject: Re: [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@...e.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@...e.cz> Acked-by: Hugh Dickins <hugh@...itas.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@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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