Fix GHSA-3qgc-jrrr-25jv

The original code is error-prone due to the "best fit mapping" that
happens with the argument parsing but not with the query string.
When we get a non-ASCII character, try to remap it and see if it becomes
a hyphen.

An alternative approach is to create a custom main `wmain` receiving
wide-character variations that does the ANSI transformation with the
best-fit mapping, but that's more error-prone and could cause unexpected
breakage.

Another alternative was just don't doing this check altogether and
always check for `cgi || fastcgi` instead, but that breaks real-world
use-cases.

Author: ndossche

sapi/cgi/cgi_main.c

@@ -1798,8 +1798,13 @@ int main(int argc, char *argv[])
 		}
 	}
 
+	/* Apache CGI will pass the query string to the command line if it doesn't contain a '='.
+	 * This can create an issue where a malicious request can pass command line arguments to
+	 * the executable. Ideally we skip argument parsing when we're in cgi or fastcgi mode,
+	 * but that breaks PHP scripts on Linux with a hashbang: `#!/php-cgi -d option=value`.
+	 * Therefore, this code only prevents passing arguments if the query string starts with a '-'.
+	 * Similarly, scripts spawned in subprocesses on Windows may have the same issue. */
 	if((query_string = getenv("QUERY_STRING")) != NULL && strchr(query_string, '=') == NULL) {
-		/* we've got query string that has no = - apache CGI will pass it to command line */
 		unsigned char *p;
 		decoded_query_string = strdup(query_string);
 		php_url_decode(decoded_query_string, strlen(decoded_query_string));
@@ -1809,6 +1814,22 @@ int main(int argc, char *argv[])
 		if(*p == '-') {
 			skip_getopt = 1;
 		}
+
+		/* On Windows we have to take into account the "best fit" mapping behaviour. */
+#ifdef PHP_WIN32
+		if (*p >= 0x80) {
+			wchar_t wide_buf[1];
+			wide_buf[0] = *p;
+			char char_buf[4];
+			size_t wide_buf_len = sizeof(wide_buf) / sizeof(wide_buf[0]);
+			size_t char_buf_len = sizeof(char_buf) / sizeof(char_buf[0]);
+			if (WideCharToMultiByte(CP_ACP, 0, wide_buf, wide_buf_len, char_buf, char_buf_len, NULL, NULL) == 0
+				|| char_buf[0] == '-') {
+				skip_getopt = 1;
+			}
+		}
+#endif
+
 		free(decoded_query_string);
 	}
 

sapi/cgi/tests/ghsa-3qgc-jrrr-25jv.phpt

@@ -0,0 +1,38 @@
+--TEST--
+GHSA-3qgc-jrrr-25jv
+--SKIPIF--
+<?php
+include 'skipif.inc';
+if (PHP_OS_FAMILY !== "Windows") die("skip Only for Windows");
+
+$codepage = trim(shell_exec("powershell Get-ItemPropertyValue HKLM:\\SYSTEM\\CurrentControlSet\\Control\\Nls\\CodePage ACP"));
+if ($codepage !== '932' && $codepage !== '936' && $codepage !== '950') die("skip Wrong codepage");
+?>
+--FILE--
+<?php
+include 'include.inc';
+
+$filename = __DIR__."/GHSA-3qgc-jrrr-25jv_tmp.php";
+$script = '<?php echo "hello "; echo "world"; ?>';
+file_put_contents($filename, $script);
+
+$php = get_cgi_path();
+reset_env_vars();
+
+putenv("SERVER_NAME=Test");
+putenv("SCRIPT_FILENAME=$filename");
+putenv("QUERY_STRING=%ads");
+putenv("REDIRECT_STATUS=1");
+
+passthru("$php -s");
+
+?>
+--CLEAN--
+<?php
+@unlink(__DIR__."/GHSA-3qgc-jrrr-25jv_tmp.php");
+?>
+--EXPECTF--
+X-Powered-By: PHP/%s
+Content-type: %s
+
+hello world