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>
1 parent 704b862
Raw File
checkincludes.pl
#!/usr/bin/env perl
#
# checkincludes: find/remove files included more than once
#
# Copyright abandoned, 2000, Niels Kristian Bech Jensen <nkbj@image.dk>.
# Copyright 2009 Luis R. Rodriguez <mcgrof@gmail.com>
#
# This script checks for duplicate includes. It also has support
# to remove them in place. Note that this will not take into
# consideration macros so you should run this only if you know
# you do have real dups and do not have them under #ifdef's. You
# could also just review the results.

use strict;

sub usage {
	print "Usage: checkincludes.pl [-r]\n";
	print "By default we just warn of duplicates\n";
	print "To remove duplicated includes in place use -r\n";
	exit 1;
}

my $remove = 0;

if ($#ARGV < 0) {
	usage();
}

if ($#ARGV >= 1) {
	if ($ARGV[0] =~ /^-/) {
		if ($ARGV[0] eq "-r") {
			$remove = 1;
			shift;
		} else {
			usage();
		}
	}
}

my $dup_counter = 0;

foreach my $file (@ARGV) {
	open(my $f, '<', $file)
	    or die "Cannot open $file: $!.\n";

	my %includedfiles = ();
	my @file_lines = ();

	while (<$f>) {
		if (m/^\s*#\s*include\s*[<"](\S*)[>"]/o) {
			++$includedfiles{$1};
		}
		push(@file_lines, $_);
	}

	close($f);

	if (!$remove) {
		foreach my $filename (keys %includedfiles) {
			if ($includedfiles{$filename} > 1) {
				print "$file: $filename is included more than once.\n";
				++$dup_counter;
			}
		}
		next;
	}

	open($f, '>', $file)
	    or die("Cannot write to $file: $!");

	my $dups = 0;
	foreach (@file_lines) {
		if (m/^\s*#\s*include\s*[<"](\S*)[>"]/o) {
			foreach my $filename (keys %includedfiles) {
				if ($1 eq $filename) {
					if ($includedfiles{$filename} > 1) {
						$includedfiles{$filename}--;
						$dups++;
						++$dup_counter;
					} else {
						print {$f} $_;
					}
				}
			}
		} else {
			print {$f} $_;
		}
	}
	if ($dups > 0) {
		print "$file: removed $dups duplicate includes\n";
	}
	close($f);
}

if ($dup_counter == 0) {
	print "No duplicate includes found.\n";
}
back to top