Gyumeijie/c_c-memory-errors-collection

c and c++ common memory errors collection

内存分配大小类型不匹配

struct Test {
    uint64_t first; 
    uint64_t second;
    uint64_t third;
};

int main()
{
    Test* test = (Test*)malloc(sizeof(void*));
    std::cout << test << std::endl;
    std::cout <<&test->second << std::endl;
    std::cout <<&test->third << std::endl;
    test->first = 100;
    test->second = 200;
    test->third = 300;
    uint64_t* i = (uint64_t*)malloc(sizeof(void*));
    std::cout << i << std::endl;
    std::cout << *i << std::endl;
}

0x7fe08d402b60
0x7fe08d402b68
0x7fe08d402b70
0x7fe08d402b70
300

未初始话内存访问

内存申请，并不保证其值是有效的，在使用前一定一定要初始化

char *pStr = (char*) malloc(512);
char c = pStr[0]; // the contents of pStr were not initialized
void func()
{ 
    int a; 
    int b = a * 4; // uninitialized read of variable a 
}

内存泄露

特别是异常分支，容易忘记释放

char *pStr = (char*) malloc(512);
return;

不匹配内存分配释放函数

char *s = (char*) malloc(5); 
delete s;

指针使用前要判空

void foo(char* p)
{
   if (p == nullptr) {
       return;
   }
}

指针释放后应该置空，防止再次使用

   delete p;
   p = nullptr
   // ...

https://github.com/google/sanitizers/wiki/AddressSanitizer