Date: Thu, 2 Feb 2017 06:21:42 -0800 From: Kees Cook <keescook@...omium.org> To: Bhupesh Sharma <bhsharma@...hat.com> Cc: "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>, "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Daniel Cashman <dcashman@...gle.com>, Michael Ellerman <mpe@...erman.id.au>, bhupesh.linux@...il.com, Alexander Graf <agraf@...e.com>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Paul Mackerras <paulus@...ba.org>, Anatolij Gustschin <agust@...x.de>, Alistair Popple <alistair@...ple.id.au>, Matt Porter <mporter@...nel.crashing.org>, Vitaly Bordug <vitb@...nel.crashing.org>, Scott Wood <oss@...error.net>, Kumar Gala <galak@...nel.crashing.org>, Daniel Cashman <dcashman@...roid.com> Subject: Re: [PATCH 0/2] RFC: Adjust powerpc ASLR elf randomness On Wed, Feb 1, 2017 at 9:42 PM, Bhupesh Sharma <bhsharma@...hat.com> wrote: > This RFC patchset tries to make the powerpc ASLR elf randomness > implementation similar to other ARCHs (like x86). > > The 1st patch introduces the support of ARCH_MMAP_RND_BITS in powerpc > mmap implementation to allow a sane balance between increased randomness > in the mmap address of ASLR elfs and increased address space > fragmentation. > > The 2nd patch increases the ELF_ET_DYN_BASE value from the current > hardcoded value of 0x2000_0000 to something more practical, > i.e. TASK_SIZE - PAGE_SHIFT (which makes sense especially for > 64-bit platforms which would like to utilize more randomization > in the load address of a PIE elf). I don't think you want this second patch. Moving ELF_ET_DYN_BASE to the top of TASK_SIZE means you'll be constantly colliding with stack and mmap randomization. 0x20000000 is way better since it randomizes up from there towards the mmap area. Is there a reason to avoid the 32-bit memory range for the ELF addresses? -Kees -- Kees Cook Pixel Security
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.