Description:
------------
string.c:
```
PHPAPI size_t php_strip_tags_ex(char *rbuf, size_t len, uint8_t *stateptr, const char *allow, size_t allow_len, zend_bool allow_tag_spaces)
{
	...
			case '>':
                ...
					case 2: /* PHP */
						if (!br && lc != '\"' && *(p-1) == '?') {
```

PoC:
```
<?php

$stream = fopen('php://memory', 'w+');
fputs($stream, "<?\n>");
rewind($stream);
var_dump(fgetss($stream));
var_dump(fgetss($stream));
fclose($stream);

?>
```

Fix:
```
if (!br && lc != '\"' && p >= buf + 1 && *(p-1) == '?') {
```