Description:
------------
In the file ext/standard/string.c, the PHP_FUNCTION wordwrap has the following
code:
PHP_FUNCTION(wordwrap)
{
    zend_long linelength = 75;
    ZEND_PARSE_PARAMETERS_START(1, 4)
    ...
    Z_PARAM_LONG(linelength)
    Z_PARAM_STRING(breakchar, breakchar_len)
    Z_PARAM_BOOL(docut)
    ZEND_PARSE_PARAMETERS_END();
    ...

    if (linelength == 0 && docut) {
	RETURN_THROWS();
    }

    if (breakchar_len == 1 && !docut) {
        ...
    } else {
        ...
        for (current = 0; current < (zend_long)ZSTR_LEN(text); current++) {
            if (chk == 0) {
	      alloced += (size_t) (((ZSTR_LEN(text) - current + 1)/linelength + 1) * breakchar_len) + 1;
	      newtext = zend_string_extend(newtext, alloced, 0);
	      chk = (size_t) ((ZSTR_LEN(text) - current)/linelength) + 1;
	    }
            ...
        }
    }
}

When the parameters satisfy linelength == 0 && docut == 0 && breakchar_len > 1,
the variable linelength may be used as a divisor in the for loop, leading to a divide by zero bug.

Here is the link to the related code location:
https://github.com/php/php-src/blob/e86a0a905dd091a82bea2ff56845297171ea7249/ext/standard/string.c#L954