exper

src/experimental/asan_cgroups/limit_memory.sh

@@ -33,24 +33,31 @@
 # task.
 #
 
+# 输出脚本的作者信息
 echo "cgroup tool for afl-fuzz by <samir.hakim@nyu.edu> and <dwheeler@ida.org>"
 echo
 
+# 清除NEW_USER变量的值
 unset NEW_USER
+# 设置默认内存限制为50MB
 MEM_LIMIT="50"
 
+# 解析命令行参数
 while getopts "+u:m:" opt; do
 
   case "$opt" in
 
+    # -u 参数用于指定运行fuzzer的用户
     "u")
          NEW_USER="$OPTARG"
          ;;
 
+    # -m 参数用于设置内存限制，单位为MB
     "m")
-         MEM_LIMIT="$[OPTARG]"
+         MEM_LIMIT="$OPTARG"
          ;;
 
+    # 如果遇到未知参数，退出脚本
     "?")
          exit 1
          ;;
@@ -59,17 +66,22 @@ while getopts "+u:m:" opt; do
 
 done
 
+# 检查内存限制是否低于安全阈值
 if [ "$MEM_LIMIT" -lt "5" ]; then
   echo "[-] Error: malformed or dangerously low value of -m." 1>&2
   exit 1
 fi
 
+# 移除已解析的选项，保留fuzz命令
 shift $((OPTIND-1))
 
+# 获取目标二进制文件路径
 TARGET_BIN="$1"
 
+# 检查是否提供了必要的参数
 if [ "$TARGET_BIN" = "" -o "$NEW_USER" = "" ]; then
 
+  # 输出使用说明
   cat 1>&2 <<_EOF_
 Usage: $0 [ options ] -- /path/to/afl-fuzz [ ...afl options... ]
 
@@ -89,75 +101,81 @@ conjunction with '-m none' passed to the afl-fuzz binary itself, say:
 
 _EOF_
 
+  # 因为缺少必要的参数，退出脚本
   exit 1
 
 fi
 
-# Basic sanity checks
-
+# 基本的系统检查
+# 检查是否为Linux系统
 if [ ! "`uname -s`" = "Linux" ]; then
  echo "[-] Error: this tool does not support non-Linux systems." 1>&2
  exit 1
 fi
 
+# 检查是否以root用户运行脚本
 if [ ! "`id -u`" = "0" ]; then
  echo "[-] Error: you need to run this script as root (sorry!)." 1>&2
  exit 1
 fi
 
+# 检查是否安装了cgroup工具
 if ! type cgcreate 2>/dev/null 1>&2; then
 
   echo "[-] Error: you need to install cgroup tools first." 1>&2
 
+  # 根据包管理器提供安装命令建议
   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
 
+  # 因为缺少必要的工具，退出脚本
   exit 1
 
 fi
 
+# 检查指定的用户是否存在
 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-$$"
+# 创建一个新的cgroup路径（如果必要），使用PID键值组来确保并行的afl-fuzz任务相互独立
+CID="afl-$NEW_USER-$"
 
 CPATH="/sys/fs/cgroup/memory/$CID"
 
+# 如果路径不存在，则创建cgroup
 if [ ! -d "$CPATH" ]; then
 
   cgcreate -a "$NEW_USER" -g memory:"$CID" || exit 1
 
 fi
 
-# Set the appropriate limit...
-
+# 设置内存限制
+# 如果系统支持交换空间限制，则同时设置内存和交换空间限制
 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
 
+# 如果系统有启用交换空间，则要求先禁用交换空间
 elif grep -qE 'partition|file' /proc/swaps; then
 
   echo "[-] Error: your system requires swap to be disabled first (swapoff -a)." 1>&2
   exit 1
 
+# 如果系统不支持交换空间限制，则仅设置内存限制
 else
 
   echo "${MEM_LIMIT}M" > "$CPATH/memory.limit_in_bytes" || exit 1
 
 fi
 
-# All right. At this point, we can just run the command.
-
+# 运行fuzz命令，并确保其在设置的cgroup内存限制下执行
 cgexec -g "memory:$CID" su -c "$*" "$NEW_USER"
 
+# 删除cgroup以清理资源
 cgdelete -g "memory:$CID"