Synopsis

Do not read uninitialized memory.

Enabled by default

Yes

Severity/Certainty

High/Medium

Full description

Uninitialized automatic variables or dynamically allocated memory has indeterminate values, which for objects of some types, can be a trap representation. Reading such trap representations is undefined behavior; it can cause a program to behave in an unexpected manner and provide an avenue for attack. This check is identical to MISRAC2004-1.2_b, MISRAC2012-Rule-9.1_d, SPC-uninit-struct-field.

Coding standards

Code examples

The following code example fails the check and will give a warning:

struct st {
  int x;
  int y;
};

void example(void) {
  int a;
  struct st str;
  a = str.x;
}

The following code example passes the check and will not give a warning about this issue:

struct st {
  int x;
  int y;
};

void example(int i) {
  int a;
  struct st str;
  str.x = i;
  a = str.x;
}