Fix GHSA-wpj3-hf5j-x4v4: __Host-/__Secure- cookie bypass due to partial CVE-2022-31629 fix

The check happened too early as later code paths may perform more
mangling rules. Move the check downwards right before adding the actual
variable.

ext/standard/tests/ghsa-wpj3-hf5j-x4v4.phpt

@@ -0,0 +1,63 @@
+--TEST--
+ghsa-wpj3-hf5j-x4v4 (__Host-/__Secure- cookie bypass due to partial CVE-2022-31629 fix)
+--COOKIE--
+..Host-test=ignore_1;
+._Host-test=ignore_2;
+.[Host-test=ignore_3;
+_.Host-test=ignore_4;
+__Host-test=ignore_5;
+_[Host-test=ignore_6;
+[.Host-test=ignore_7;
+[_Host-test=ignore_8;
+[[Host-test=ignore_9;
+..Host-test[]=ignore_10;
+._Host-test[]=ignore_11;
+.[Host-test[]=ignore_12;
+_.Host-test[]=ignore_13;
+__Host-test[]=legitimate_14;
+_[Host-test[]=legitimate_15;
+[.Host-test[]=ignore_16;
+[_Host-test[]=ignore_17;
+[[Host-test[]=ignore_18;
+..Secure-test=ignore_1;
+._Secure-test=ignore_2;
+.[Secure-test=ignore_3;
+_.Secure-test=ignore_4;
+__Secure-test=ignore_5;
+_[Secure-test=ignore_6;
+[.Secure-test=ignore_7;
+[_Secure-test=ignore_8;
+[[Secure-test=ignore_9;
+..Secure-test[]=ignore_10;
+._Secure-test[]=ignore_11;
+.[Secure-test[]=ignore_12;
+_.Secure-test[]=ignore_13;
+__Secure-test[]=legitimate_14;
+_[Secure-test[]=legitimate_15;
+[.Secure-test[]=ignore_16;
+[_Secure-test[]=ignore_17;
+[[Secure-test[]=ignore_18;
+--FILE--
+<?php
+var_dump($_COOKIE);
+?>
+--EXPECT--
+array(3) {
+  ["__Host-test"]=>
+  array(1) {
+    [0]=>
+    string(13) "legitimate_14"
+  }
+  ["_"]=>
+  array(2) {
+    ["Host-test["]=>
+    string(13) "legitimate_15"
+    ["Secure-test["]=>
+    string(13) "legitimate_15"
+  }
+  ["__Secure-test"]=>
+  array(1) {
+    [0]=>
+    string(13) "legitimate_14"
+  }
+}

main/php_variables.c

@@ -89,6 +89,21 @@ PHPAPI void php_register_known_variable(const char *var_name, size_t var_name_le
 	php_register_variable_quick(var_name, var_name_len, value, symbol_table);
 }
 
+/* Discard variable if mangling made it start with __Host-, where pre-mangling it did not start with __Host-
+ * Discard variable if mangling made it start with __Secure-, where pre-mangling it did not start with __Secure- */
+static bool php_is_forbidden_variable_name(const char *mangled_name, size_t mangled_name_len, const char *pre_mangled_name)
+{
+	if (mangled_name_len >= sizeof("__Host-")-1 && strncmp(mangled_name, "__Host-", sizeof("__Host-")-1) == 0 && strncmp(pre_mangled_name, "__Host-", sizeof("__Host-")-1) != 0) {
+		return true;
+	}
+
+	if (mangled_name_len >= sizeof("__Secure-")-1 && strncmp(mangled_name, "__Secure-", sizeof("__Secure-")-1) == 0 && strncmp(pre_mangled_name, "__Secure-", sizeof("__Secure-")-1) != 0) {
+		return true;
+	}
+
+	return false;
+}
+
 PHPAPI void php_register_variable_ex(const char *var_name, zval *val, zval *track_vars_array)
 {
 	char *p = NULL;
@@ -139,20 +154,6 @@ PHPAPI void php_register_variable_ex(const char *var_name, zval *val, zval *trac
 	}
 	var_len = p - var;
 
-	/* Discard variable if mangling made it start with __Host-, where pre-mangling it did not start with __Host- */
-	if (strncmp(var, "__Host-", sizeof("__Host-")-1) == 0 && strncmp(var_name, "__Host-", sizeof("__Host-")-1) != 0) {
-		zval_ptr_dtor_nogc(val);
-		free_alloca(var_orig, use_heap);
-		return;
-	}
-
-	/* Discard variable if mangling made it start with __Secure-, where pre-mangling it did not start with __Secure- */
-	if (strncmp(var, "__Secure-", sizeof("__Secure-")-1) == 0 && strncmp(var_name, "__Secure-", sizeof("__Secure-")-1) != 0) {
-		zval_ptr_dtor_nogc(val);
-		free_alloca(var_orig, use_heap);
-		return;
-	}
-
 	if (var_len==0) { /* empty variable name, or variable name with a space in it */
 		zval_ptr_dtor_nogc(val);
 		free_alloca(var_orig, use_heap);
@@ -256,6 +257,12 @@ PHPAPI void php_register_variable_ex(const char *var_name, zval *val, zval *trac
 					return;
 				}
 			} else {
+				if (php_is_forbidden_variable_name(index, index_len, var_name)) {
+					zval_ptr_dtor_nogc(val);
+					free_alloca(var_orig, use_heap);
+					return;
+				}
+
 				gpc_element_p = zend_symtable_str_find(symtable1, index, index_len);
 				if (!gpc_element_p) {
 					zval tmp;
@@ -293,6 +300,12 @@ plain_var:
 				zval_ptr_dtor_nogc(val);
 			}
 		} else {
+			if (php_is_forbidden_variable_name(index, index_len, var_name)) {
+				zval_ptr_dtor_nogc(val);
+				free_alloca(var_orig, use_heap);
+				return;
+			}
+
 			zend_ulong idx;
 
 			/*