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...

int main(int argc, char *argv[]) {
  char *buff;

  buff = (char *) malloc(BUFSIZE);
  if (!buff) {
     /* handle error condition */
  }
  ...
  strncpy(buff, argv[1], BUFSIZE-1);
  ...
  free(buff);

}

...

Priority: P18 Level: L18

Reading memory that has already been freed can lead to abnormal program termination and denial-of-service attacks. Writing memory that has already been freed can lead to the execution of arbitrary code with the permissions of the vulnerable process.

References

• ISO/IEC 9899-1999 Section 7.20.3.2, The free function
• Seacord 05 Chapter 4, Dynamic Memory Management
• Kerrighan 88 Section 7.8.5, Storage Management
• OWASP, Using freed memory http://www.owasp.org/index.php/Using_freed_memory