+Jakub Jelinek, who helped us migrate asan's shadow from high addresses
to 0x7fff7000 for a significant ~5% performance and code size gain.
(a few years ago)
--kcc
On Mon, Aug 7, 2017 at 10:24 AM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
Hello,
The recent "binfmt_elf: use ELF_ET_DYN_BASE only for PIE" patch:
https://github.com/torvalds/linux/commit/ eab09532d40090698b05a07c1c87f3 9fdbc5fab5
breaks user-space AddressSanitizer. AddressSanitizer makes assumptions
about address space layout for substantial performance gains. There
are multiple people complaining about this already:
https://github.com/google/sanitizers/issues/837
https://twitter.com/kayseesee/status/894594085608013825
https://bugzilla.kernel.org/show_bug.cgi?id=196537
AddressSanitizer maps shadow memory at [0x00007fff7000-0x10007fff7fff]
expecting that non-pie binaries will be below 2GB and pie
binaries/modules will be at 0x55 or 0x7f. This is not the first time
kernel address space shuffling breaks sanitizers. The last one was the
move to 0x55.
Is it possible to make this change less aggressive and keep the
executable under 2GB?
In future please be mindful of user-space sanitizers and talk to
address-sanitizer@googlegroups.com before shuffling address space.
Thanks
