False negative: memory leak through a pointer-to-pointer alias

[Rodri]

Hi, I found a false negative regarding the rule memleak.

Cppcheck misses the leak when the allocated buffer is accessed through a pointer-to-pointer alias.

#include <stdlib.h>

int f(void) {
  int result = 0;
  char *a = malloc(10);
  char **b = &a;
  if (*b) {
    (*b)[0] = 0;
    result = (*b)[0];
  }
  return result;
}

Actual result

Cppcheck does not report memleak. Removing b and replacing each *b access with a produces the warning.

Expected result

Cppcheck should report the missing free in both forms.

Verification

The issue was reproduced with:

cppcheck --output-format=xmlv2 --enable=all malloc_alias.c

Version: 2.21.0

[CHR]

Looks like a special case of https://trac.cppcheck.net/ticket/1606