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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
mkmakefile 
#!/bin/sh
# Generates a small Makefile used in the root of the output
# directory, to allow make to be started from there.
# The Makefile also allow for more convinient build of external modules

# Usage
# $1 - Kernel src directory
# $2 - Output directory
# $3 - version
# $4 - patchlevel


test ! -r $2/Makefile -o -O $2/Makefile || exit 0
# Only overwrite automatically generated Makefiles
# (so we do not overwrite kernel Makefile)
if test -e $2/Makefile && ! grep -q Automatically $2/Makefile
then
	exit 0
fi
if [ "${quiet}" != "silent_" ]; then
	echo "  GEN     $2/Makefile"
fi

cat << EOF > $2/Makefile
# Automatically generated by $0: don't edit

VERSION = $3
PATCHLEVEL = $4

lastword = \$(word \$(words \$(1)),\$(1))
makedir := \$(dir \$(call lastword,\$(MAKEFILE_LIST)))

ifeq ("\$(origin V)", "command line")
VERBOSE := \$(V)
endif
ifneq (\$(VERBOSE),1)
Q := @
endif

MAKEARGS := -C $1
MAKEARGS += O=\$(if \$(patsubst /%,,\$(makedir)),\$(CURDIR)/)\$(patsubst %/,%,\$(makedir))

MAKEFLAGS += --no-print-directory

.PHONY: __sub-make \$(MAKECMDGOALS)

__sub-make:
	\$(Q)\$(MAKE) \$(MAKEARGS) \$(MAKECMDGOALS)

\$(filter-out __sub-make, \$(MAKECMDGOALS)): __sub-make
	@:
EOF
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