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
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>
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adjust_autoksyms.sh
#!/bin/sh
# Script to create/update include/generated/autoksyms.h and dependency files
#
# Copyright: (C) 2016 Linaro Limited
# Created by: Nicolas Pitre, January 2016
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
# Create/update the include/generated/autoksyms.h file from the list
# of all module's needed symbols as recorded on the third line of
# .tmp_versions/*.mod files.
#
# For each symbol being added or removed, the corresponding dependency
# file's timestamp is updated to force a rebuild of the affected source
# file. All arguments passed to this script are assumed to be a command
# to be exec'd to trigger a rebuild of those files.
set -e
cur_ksyms_file="include/generated/autoksyms.h"
new_ksyms_file="include/generated/autoksyms.h.tmpnew"
info() {
if [ "$quiet" != "silent_" ]; then
printf " %-7s %s\n" "$1" "$2"
fi
}
info "CHK" "$cur_ksyms_file"
# Use "make V=1" to debug this script.
case "$KBUILD_VERBOSE" in
*1*)
set -x
;;
esac
# We need access to CONFIG_ symbols
case "${KCONFIG_CONFIG}" in
*/*)
. "${KCONFIG_CONFIG}"
;;
*)
# Force using a file from the current directory
. "./${KCONFIG_CONFIG}"
esac
# In case it doesn't exist yet...
if [ -e "$cur_ksyms_file" ]; then touch "$cur_ksyms_file"; fi
# Generate a new ksym list file with symbols needed by the current
# set of modules.
cat > "$new_ksyms_file" << EOT
/*
* Automatically generated file; DO NOT EDIT.
*/
EOT
[ "$(ls -A "$MODVERDIR")" ] &&
sed -ns -e '3{s/ /\n/g;/^$/!p;}' "$MODVERDIR"/*.mod | sort -u |
while read sym; do
if [ -n "$CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX" ]; then
sym="${sym#_}"
fi
echo "#define __KSYM_${sym} 1"
done >> "$new_ksyms_file"
# Special case for modversions (see modpost.c)
if [ -n "$CONFIG_MODVERSIONS" ]; then
echo "#define __KSYM_module_layout 1" >> "$new_ksyms_file"
fi
# Extract changes between old and new list and touch corresponding
# dependency files.
changed=$(
count=0
sort "$cur_ksyms_file" "$new_ksyms_file" | uniq -u |
sed -n 's/^#define __KSYM_\(.*\) 1/\1/p' | tr "A-Z_" "a-z/" |
while read sympath; do
if [ -z "$sympath" ]; then continue; fi
depfile="include/config/ksym/${sympath}.h"
mkdir -p "$(dirname "$depfile")"
touch "$depfile"
echo $((count += 1))
done | tail -1 )
changed=${changed:-0}
if [ $changed -gt 0 ]; then
# Replace the old list with tne new one
old=$(grep -c "^#define __KSYM_" "$cur_ksyms_file" || true)
new=$(grep -c "^#define __KSYM_" "$new_ksyms_file" || true)
info "KSYMS" "symbols: before=$old, after=$new, changed=$changed"
info "UPD" "$cur_ksyms_file"
mv -f "$new_ksyms_file" "$cur_ksyms_file"
# Then trigger a rebuild of affected source files
exec $@
else
rm -f "$new_ksyms_file"
fi
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