mm: insure topdown mmap chooses addresses above security minimum
Ingo Molnar
mingo at kernel.org
Wed Sep 25 13:44:36 EDT 2013
* Timothy Pepper <timothy.c.pepper at linux.intel.com> wrote:
> On Wed 25 Sep at 09:30:49 +0200 mingo at kernel.org said:
> > > info.flags = VM_UNMAPPED_AREA_TOPDOWN;
> > > info.length = len;
> > > - info.low_limit = PAGE_SIZE;
> > > + info.low_limit = max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));
> > > info.high_limit = mm->mmap_base;
> > > info.align_mask = filp ? get_align_mask() : 0;
> > > info.align_offset = pgoff << PAGE_SHIFT;
> >
> > There appears to be a lot of repetition in these methods - instead of
> > changing 6 places it would be more future-proof to first factor out the
> > common bits and then to apply the fix to the shared implementation.
>
> Besides that existing redundancy in the multiple somewhat similar
> arch_get_unmapped_area_topdown() functions, I was expecting people might
> question the added redundancy of the six instances of:
>
> max(PAGE_SIZE, PAGE_ALIGN(mmap_min_addr));
That redundancy would be automatically addressed by my suggestion.
Thanks,
Ingo
More information about the linux-arm-kernel
mailing list