The patch titled
Subject: arm64: move COMPAT_ELF_ET_DYN_BASE lower in the address space
has been added to the -mm tree. Its filename is
arm64-move-compat_elf_et_dyn_base-lower-in-the-address-space.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/arm64-move-compat_elf_et_dyn_base-lower-in-the-address-space.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/arm64-move-compat_elf_et_dyn_base-lower-in-the-address-space.patch
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------------------------------------------------------
From: Rik van Riel <riel@xxxxxxxxxx>
Subject: arm64: move COMPAT_ELF_ET_DYN_BASE lower in the address space
When setting up mmap_base, we take care to start the mmap base below the
maximum extent to which the stack will grow. However, we take no such
precautions with PIE binaries, which are placed at 2/3 of TASK_SIZE plus a
random offset. As a result, 32 bit PIE binaries can end up smack in the
middle of where the stack (which is randomized down) is supposed to go.
That problem can be avoided by putting the 32 bit ELF_ET_DYN_BASE at
256MB, which is a value linux-hardened and grsecurity have used for a long
time now without any known (to me) bug reports.
Link: http://lkml.kernel.org/r/20170602152010.2064-6-riel@xxxxxxxxxx
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Daniel Micay <danielmicay@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Larry Woodman <lwoodman@xxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Florian Weimer <fweimer@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/elf.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN arch/arm64/include/asm/elf.h~arm64-move-compat_elf_et_dyn_base-lower-in-the-address-space arch/arm64/include/asm/elf.h
--- a/arch/arm64/include/asm/elf.h~arm64-move-compat_elf_et_dyn_base-lower-in-the-address-space
+++ a/arch/arm64/include/asm/elf.h
@@ -173,7 +173,7 @@ extern int arch_setup_additional_pages(s
#ifdef CONFIG_COMPAT
-#define COMPAT_ELF_ET_DYN_BASE (2 * TASK_SIZE_32 / 3)
+#define COMPAT_ELF_ET_DYN_BASE (0x10000000UL)
/* AArch32 registers. */
#define COMPAT_ELF_NGREG 18
_
Patches currently in -mm which might be from riel@xxxxxxxxxx are
binfmt_elf-document-load_bias-a-little-bit.patch
x86-elf-move-32-bit-elf_et_dyn_base-to-256mb.patch
x86-mmap-properly-account-for-stack-randomization-in-mmap_base.patch
arm64-mmap-properly-account-for-stack-randomization-in-mmap_base.patch
arm64-move-compat_elf_et_dyn_base-lower-in-the-address-space.patch
powerpcmmap-properly-account-for-stack-randomization-in-mmap_base.patch
randomstackprotect-introduce-get_random_canary-function.patch
forkrandom-use-get_random_canary-to-set-tsk-stack_canary.patch
x86-ascii-armor-the-x86_64-boot-init-stack-canary.patch
arm64-ascii-armor-the-arm64-boot-init-stack-canary.patch
sh64-ascii-armor-the-sh64-boot-init-stack-canary.patch
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