Question

我正在运行一段代码，其中包含2个函数并运行valgrind，获取大小为1的无效读取。我们无法识别问题请帮助

RrSSystemIntf_i::RrSSystemIntf_i()
{
  RrXmlReader cfgReader;
  char* configFile = cfgFile;
  char* pss;
  U pssId;

  if (ROK != cfgReader.readConfig(configFile, (char*)"ABCD", (char*)"RR_NODES",
                                  &pss)) {
    RR_ALERT("RrSSystemIntf_i: readConfig failed. exiting...");
    _exit();
  }

  pssId = atoi(pss);
}


int RrXmlReader::readConfig(char*& confFile, char* elem_type, char* val_type,
                            char** ret_val)
{
  reader.getValue(curContext, val_type, value);

  if (NULL == value) {
    RR_ALERT("XmlFactory::rrNodes : Config Error: %s missing from %s", val_type,
             elem_type);
    return RFAILED;
  }

  string returnStr;
  returnStr = std::string(value);
  *ret_val  = (char*)(returnStr.c_str());
  return ROK;
}

Valgrind追踪：

==30007== Invalid read of size 1
==30007==    at 0x33296345CA: ____strtol_l_internal (in /lib64/libc-2.5.so)
==30007==    by 0x52D5A64: RrS7SystemIntf_i::RrS7SystemIntf_i() (stdlib.h:336)
==30007==    by 0x52AA9E7: RrObInit::initOb(int, char**) (RrObInit.cpp:360)
==30007==    by 0x52ACF6D: RrObInit::getInstance() (RrObInit.cpp:636)
==30007==    by 0x52AE909: tst (RrTst.cpp:515)
==30007==    by 0x4C12694: Init (gen.c:581)
==30007==    by 0x4C1135C: Main (mtss.c:484)
==30007==    by 0x52ADD7B: main (RrTst.cpp:225)
==30007==  Address 0x8e9dc28 is 24 bytes inside a block of size 28 free'd
==30007==    at 0x4A05743: operator delete(void*) (vg_replace_malloc.c:346)
==30007==    by 0x52FC330: RrXmlReader::readConfig(char*&, char*, char*, char**)    (basic_string.h:233)
==30007==    by 0x52D590B: RrS7SystemIntf_i::RrgS7SystemIntf_i() (RrS7System_i.cpp:325)

感谢您的帮助。

Answer 1

问题从这一行开始：

*ret_val  = (char*)(returnStr.c_str());

您将通过ret_val返回一个从readConfig返回时无效的地址。

执行时，Valgrind会捕获内存访问问题：

pssId = atoi(pss);

因为pss指向此时无效的内存。

我的建议：

将readConfig更改为

int RrXmlReader::readConfig(char*& confFile, char* elem_type, char* val_type,
                            std::string& ret_val)

valgrind中读取大小为1的读取无效

1 个答案: