Add American Fuzzy Lop (afl) to third_party/afl/

third_party/afl/src/experimental/asan_cgroups/limit_memory.sh

+#!/usr/bin/env bash
+#
+# american fuzzy lop - limit memory using cgroups
+# -----------------------------------------------
+#
+# Written by Samir Khakimov <samir.hakim@nyu.edu> and
+#            David A. Wheeler <dwheeler@ida.org>
+#
+# Edits to bring the script in line with afl-cmin and other companion scripts
+# by Michal Zalewski <lcamtuf@google.com>. All bugs are my fault.
+#
+# Copyright 2015 Institute for Defense Analyses.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# This tool allows the amount of actual memory allocated to a program
+# to be limited on Linux systems using cgroups, instead of the traditional
+# setrlimit() API. This helps avoid the address space problems discussed in
+# docs/notes_for_asan.txt.
+#
+# Important: the limit covers *both* afl-fuzz and the fuzzed binary. In some
+# hopefully rare circumstances, afl-fuzz could be killed before the fuzzed
+# task.
+#
+
+echo "cgroup tool for afl-fuzz by <samir.hakim@nyu.edu> and <dwheeler@ida.org>"
+echo
+
+unset NEW_USER
+MEM_LIMIT="50"
+
+while getopts "+u:m:" opt; do
+
+  case "$opt" in
+
+    "u")
+         NEW_USER="$OPTARG"
+         ;;
+
+    "m")
+         MEM_LIMIT="$[OPTARG]"
+         ;;
+
+    "?")
+         exit 1
+         ;;
+
+   esac
+
+done
+
+if [ "$MEM_LIMIT" -lt "5" ]; then
+  echo "[-] Error: malformed or dangerously low value of -m." 1>&2
+  exit 1
+fi
+
+shift $((OPTIND-1))
+
+TARGET_BIN="$1"
+
+if [ "$TARGET_BIN" = "" -o "$NEW_USER" = "" ]; then
+
+  cat 1>&2 <<_EOF_
+Usage: $0 [ options ] -- /path/to/afl-fuzz [ ...afl options... ]
+
+Required parameters:
+
+  -u user   - run the fuzzer as a specific user after setting up limits
+
+Optional parameters:
+
+  -m megs   - set memory limit to a specified value ($MEM_LIMIT MB)
+
+This tool configures cgroups-based memory limits for a fuzzing job to simplify
+the task of fuzzing ASAN or MSAN binaries. You would normally want to use it in
+conjunction with '-m none' passed to the afl-fuzz binary itself, say:
+
+  $0 -u joe ./afl-fuzz -i input -o output -m none /path/to/target
+
+_EOF_
+
+  exit 1
+
+fi
+
+# Basic sanity checks
+
+if [ ! "`uname -s`" = "Linux" ]; then
+ echo "[-] Error: this tool does not support non-Linux systems." 1>&2
+ exit 1
+fi
+
+if [ ! "`id -u`" = "0" ]; then
+ echo "[-] Error: you need to run this script as root (sorry!)." 1>&2
+ exit 1
+fi
+
+if ! type cgcreate 2>/dev/null 1>&2; then
+
+  echo "[-] Error: you need to install cgroup tools first." 1>&2
+
+  if type apt-get 2>/dev/null 1>&2; then
+    echo "    (Perhaps 'apt-get install cgroup-bin' will work.)" 1>&2
+  elif type yum 2>/dev/null 1>&2; then
+    echo "    (Perhaps 'yum install libcgroup-tools' will work.)" 1>&2
+  fi
+
+  exit 1
+
+fi
+
+if ! id -u "$NEW_USER" 2>/dev/null 1>&2; then
+  echo "[-] Error: user '$NEW_USER' does not seem to exist." 1>&2
+  exit 1
+fi
+
+# Create a new cgroup path if necessary... We used PID-keyed groups to keep
+# parallel afl-fuzz tasks separate from each other.
+
+CID="afl-$NEW_USER-$$"
+
+CPATH="/sys/fs/cgroup/memory/$CID"
+
+if [ ! -d "$CPATH" ]; then
+
+  cgcreate -a "$NEW_USER" -g memory:"$CID" || exit 1
+
+fi
+
+# Set the appropriate limit...
+
+if [ -f "$CPATH/memory.memsw.limit_in_bytes" ]; then
+
+  echo "${MEM_LIMIT}M" > "$CPATH/memory.limit_in_bytes" 2>/dev/null
+  echo "${MEM_LIMIT}M" > "$CPATH/memory.memsw.limit_in_bytes" || exit 1
+  echo "${MEM_LIMIT}M" > "$CPATH/memory.limit_in_bytes" || exit 1
+
+elif grep -qE 'partition|file' /proc/swaps; then
+
+  echo "[-] Error: your system requires swap to be disabled first (swapoff -a)." 1>&2
+  exit 1
+
+else
+
+  echo "${MEM_LIMIT}M" > "$CPATH/memory.limit_in_bytes" || exit 1
+
+fi
+
+# All right. At this point, we can just run the command.
+
+cgexec -g "memory:$CID" su -c "$*" "$NEW_USER"
+
+cgdelete -g "memory:$CID"