#include <stdlib.h>
int main()
{
    void *mem = malloc(sizeof(mem));
    void **ok = mem;

    mem = malloc(sizeof(mem));
    char *warn = mem;

    mem = malloc(sizeof(char));
    void **err = mem;

    *err = NULL;

    free (ok);
    free (warn);
    free (err);
    return 0;
}

The code above contains an error on the line *err = NULL (the err has been malloced to the sizeof(char), and is being assigned a pointer). Symbiotic however does not report an error.

This may be related to this warning issued by symbiotic:

KLEE: WARNING ONCE: Alignment of memory from call "malloc" is not modelled. Using alignment of 8.

symbiotic --version
version: 6.1.0-dev