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Revision c715b72c1ba406f133217b509044c38d8e714a37 authored by Kees Cook on 18 August 2017, 22:16:31 UTC, committed by Linus Torvalds on 18 August 2017, 22:32:02 UTC 
mm: revert x86_64 and arm64 ELF_ET_DYN_BASE base changes
 
Moving the x86_64 and arm64 PIE base from 0x555555554000 to 0x000100000000
broke AddressSanitizer.  This is a partial revert of:

  eab09532d400 ("binfmt_elf: use ELF_ET_DYN_BASE only for PIE")
  02445990a96e ("arm64: move ELF_ET_DYN_BASE to 4GB / 4MB")

The AddressSanitizer tool has hard-coded expectations about where
executable mappings are loaded.

The motivation for changing the PIE base in the above commits was to
avoid the Stack-Clash CVEs that allowed executable mappings to get too
close to heap and stack.  This was mainly a problem on 32-bit, but the
64-bit bases were moved too, in an effort to proactively protect those
systems (proofs of concept do exist that show 64-bit collisions, but
other recent changes to fix stack accounting and setuid behaviors will
minimize the impact).

The new 32-bit PIE base is fine for ASan (since it matches the ET_EXEC
base), so only the 64-bit PIE base needs to be reverted to let x86 and
arm64 ASan binaries run again.  Future changes to the 64-bit PIE base on
these architectures can be made optional once a more dynamic method for
dealing with AddressSanitizer is found.  (e.g.  always loading PIE into
the mmap region for marked binaries.)

Link: http://lkml.kernel.org/r/20170807201542.GA21271@beast
Fixes: eab09532d400 ("binfmt_elf: use ELF_ET_DYN_BASE only for PIE")
Fixes: 02445990a96e ("arm64: move ELF_ET_DYN_BASE to 4GB / 4MB")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Kostya Serebryany <kcc@google.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 704b862
Raw File
Makefile.modbuiltin 
# ==========================================================================
# Generating modules.builtin
# ==========================================================================

src := $(obj)

PHONY := __modbuiltin
__modbuiltin:

-include include/config/auto.conf
# tristate.conf sets tristate variables to uppercase 'Y' or 'M'
# That way, we get the list of built-in modules in obj-Y
-include include/config/tristate.conf

include scripts/Kbuild.include

ifneq ($(KBUILD_SRC),)
# Create output directory if not already present
_dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))
endif

# The filename Kbuild has precedence over Makefile
kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
include $(kbuild-file)

include scripts/Makefile.lib
__subdir-Y     := $(patsubst %/,%,$(filter %/, $(obj-Y)))
subdir-Y       += $(__subdir-Y)
subdir-ym      := $(sort $(subdir-y) $(subdir-Y) $(subdir-m))
subdir-ym      := $(addprefix $(obj)/,$(subdir-ym))
obj-Y          := $(addprefix $(obj)/,$(obj-Y))

modbuiltin-subdirs := $(patsubst %,%/modules.builtin, $(subdir-ym))
modbuiltin-mods    := $(filter %.ko, $(obj-Y:.o=.ko))
modbuiltin-target  := $(obj)/modules.builtin

__modbuiltin: $(modbuiltin-target) $(subdir-ym)
	@:

$(modbuiltin-target): $(subdir-ym) FORCE
	$(Q)(for m in $(modbuiltin-mods); do echo kernel/$$m; done;	\
	cat /dev/null $(modbuiltin-subdirs)) > $@

PHONY += FORCE

FORCE:

# Descending
# ---------------------------------------------------------------------------

PHONY += $(subdir-ym)
$(subdir-ym):
	$(Q)$(MAKE) $(modbuiltin)=$@


# Declare the contents of the .PHONY variable as phony.  We keep that
# information in a variable se we can use it in if_changed and friends.

.PHONY: $(PHONY)
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