Description:
------------
Zend/zend_API.h, around line 580:

#define CHECK_ZVAL_STRING(str) \
    if (ZSTR_VAL(str)[ZSTR_LEN(str)] != '\0') { zend_error(E_WARNING, "String is not zero-terminated (%s)", ZSTR_VAL(str)); }
#define CHECK_ZVAL_STRING_REL(str) \
    if (ZSTR_VAL(str)[ZSTR_LEN(str)] != '\0') { zend_error(E_WARNING, "String is not zero-terminated (%s) (source: %s:%d)", ZSTR_VAL(str) ZEND_FILE_LINE_RELAY_CC); }

Both of these macros pass unterminated C strings (as far as zend_string is concerned) to zend_error() as arguments to the %s format string conversion specifier. Regardless of whether the strings are implicitly terminated by whatever allocation method they use, this is generally a very bad practice from the common C format string usage semantics. If a truly unterminated C string wrapped in zend_string is passed to one of these macros, it will almost certainly result in delivery of SIGBUS (or SIGSEGV on some platforms).

Please make a terminated copy of the string in question with estrndup() or similar means, giving ZSTR_LEN() as an explicit length.