Messages in this thread | | | Subject | Re: [PATCH v2] binfmt_elf: Use ELF_ET_DYN_BASE only for PIE | From | Rik van Riel <> | Date | Wed, 21 Jun 2017 14:24:26 -0400 |
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On Wed, 2017-06-21 at 10:32 -0700, Kees Cook wrote:
> To allow for a lower ELF_ET_DYN_BASE, loaders (ET_DYN without INTERP) > are loaded into the mmap region, leaving space available for either > an > ET_EXEC binary with a fixed location or PIE being loaded into mmap by > the > loader. Only PIE programs are loaded offset from ELF_ET_DYN_BASE, > which > means architectures can now safely lower their values without risk of > loaders colliding with their subsequently loaded programs. > > For 64-bit, ELF_ET_DYN_BASE is best set to 4GB to allow runtimes to > use > the entire 32-bit address space for 32-bit pointers. > > Thanks to PaX Team, Daniel Micay, and Rik van Riel for inspiration > and > suggestions on how to implement this solution. > > Fixes: d1fd836dcf00 ("mm: split ET_DYN ASLR from mmap ASLR") > Cc: stable@vger.kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Rik van Riel <riel@redhat.com>
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