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Message-Id: <1498154792-49952-2-git-send-email-keescook@chromium.org> Date: Thu, 22 Jun 2017 11:06:29 -0700 From: Kees Cook <keescook@...omium.org> To: Andrew Morton <akpm@...ux-foundation.org> Cc: Kees Cook <keescook@...omium.org>, Russell King <linux@...linux.org.uk>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Paul Mackerras <paulus@...ba.org>, Michael Ellerman <mpe@...erman.id.au>, Martin Schwidefsky <schwidefsky@...ibm.com>, Heiko Carstens <heiko.carstens@...ibm.com>, James Hogan <james.hogan@...tec.com>, Pratyush Anand <panand@...hat.com>, Ingo Molnar <mingo@...nel.org>, linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org, kernel-hardening@...ts.openwall.com Subject: [PATCH 1/4] arm: Reduce ELF_ET_DYN_BASE Now that explicitly executed loaders are loaded in the mmap region, position PIE binaries lower in the address space to avoid possible collisions with mmap or stack regions. Signed-off-by: Kees Cook <keescook@...omium.org> --- arch/arm/include/asm/elf.h | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h index d2315ffd8f12..f13ae153fb24 100644 --- a/arch/arm/include/asm/elf.h +++ b/arch/arm/include/asm/elf.h @@ -112,12 +112,8 @@ int dump_task_regs(struct task_struct *t, elf_gregset_t *elfregs); #define CORE_DUMP_USE_REGSET #define ELF_EXEC_PAGESIZE 4096 -/* This is the location that an ET_DYN program is loaded if exec'ed. Typical - use of this is to invoke "./ld.so someprog" to test out a new version of - the loader. We need to make sure that it is out of the way of the program - that it will "exec", and that there is sufficient room for the brk. */ - -#define ELF_ET_DYN_BASE (TASK_SIZE / 3 * 2) +/* This is the base location for PIE (ET_DYN with INTERP) loads. */ +#define ELF_ET_DYN_BASE 0x400000UL /* When the program starts, a1 contains a pointer to a function to be registered with atexit, as per the SVR4 ABI. A value of 0 means we -- 2.7.4
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