ext/session: Warn when providing invalid values for session.gc_probability and session.gc_divisor

NEWS

@@ -23,6 +23,10 @@ PHP                                                                        NEWS
   . Fixed bug GH-15432 (Heap corruption when querying a vector). (cmb,
     Kamil Tekiela)
 
+- Session:
+  . Emit warnings for non-positive values of session.gc_divisor and negative values
+    of session.gc_probability. (Jorg Sowa)
+
 - Standard:
   . The "allowed_classes" option for unserialize() now throws TypeErrors and
     ValueErrors	if it is not an	array of class names. (Girgias)

ext/session/session.c

@@ -789,6 +789,44 @@ static PHP_INI_MH(OnUpdateSidBits) /* {{{ */
 }
 /* }}} */
 
+static PHP_INI_MH(OnUpdateSessionGcProbability) /* {{{ */
+{
+    SESSION_CHECK_ACTIVE_STATE;
+    SESSION_CHECK_OUTPUT_STATE;
+
+    zend_long tmp = zend_ini_parse_quantity_warn(new_value, entry->name);
+
+    if (tmp < 0) {
+        php_error_docref("session.gc_probability", E_WARNING, "session.gc_probability must be greater than or equal to 0");
+        return FAILURE;
+    }
+
+    zend_long *p = (zend_long *) ZEND_INI_GET_ADDR();
+    *p = tmp;
+
+    return SUCCESS;
+}
+/* }}} */
+
+static PHP_INI_MH(OnUpdateSessionDivisor) /* {{{ */
+{
+    SESSION_CHECK_ACTIVE_STATE;
+    SESSION_CHECK_OUTPUT_STATE;
+
+    zend_long tmp = zend_ini_parse_quantity_warn(new_value, entry->name);
+
+    if (tmp <= 0) {
+        php_error_docref("session.gc_divisor", E_WARNING, "session.gc_divisor must be greater than 0");
+        return FAILURE;
+    }
+
+    zend_long *p = (zend_long *) ZEND_INI_GET_ADDR();
+    *p = tmp;
+
+    return SUCCESS;
+}
+/* }}} */
+
 static PHP_INI_MH(OnUpdateRfc1867Freq) /* {{{ */
 {
 	int tmp = ZEND_ATOL(ZSTR_VAL(new_value));
@@ -814,8 +852,8 @@ PHP_INI_BEGIN()
 	STD_PHP_INI_ENTRY("session.name",               "PHPSESSID", PHP_INI_ALL, OnUpdateName,          session_name,       php_ps_globals,    ps_globals)
 	PHP_INI_ENTRY("session.save_handler",           "files",     PHP_INI_ALL, OnUpdateSaveHandler)
 	STD_PHP_INI_BOOLEAN("session.auto_start",       "0",         PHP_INI_PERDIR, OnUpdateBool,       auto_start,         php_ps_globals,    ps_globals)
-	STD_PHP_INI_ENTRY("session.gc_probability",     "1",         PHP_INI_ALL, OnUpdateSessionLong,          gc_probability,     php_ps_globals,    ps_globals)
+	STD_PHP_INI_ENTRY("session.gc_probability",     "1",         PHP_INI_ALL, OnUpdateSessionGcProbability,    gc_probability,     php_ps_globals,    ps_globals)
-	STD_PHP_INI_ENTRY("session.gc_divisor",         "100",       PHP_INI_ALL, OnUpdateSessionLong,          gc_divisor,         php_ps_globals,    ps_globals)
+	STD_PHP_INI_ENTRY("session.gc_divisor",         "100",       PHP_INI_ALL, OnUpdateSessionDivisor,gc_divisor,         php_ps_globals,    ps_globals)
 	STD_PHP_INI_ENTRY("session.gc_maxlifetime",     "1440",      PHP_INI_ALL, OnUpdateSessionLong,          gc_maxlifetime,     php_ps_globals,    ps_globals)
 	PHP_INI_ENTRY("session.serialize_handler",      "php",       PHP_INI_ALL, OnUpdateSerializer)
 	STD_PHP_INI_ENTRY("session.cookie_lifetime",    "0",         PHP_INI_ALL, OnUpdateCookieLifetime,cookie_lifetime,    php_ps_globals,    ps_globals)

ext/session/tests/session_gc_probability_ini.phpt

@@ -0,0 +1,65 @@
+--TEST--
+Test session.gc_probability and session.gc_divisor settings for invalid values
+--INI--
+session.gc_maxlifetime=1
+--EXTENSIONS--
+session
+--SKIPIF--
+<?php
+include('skipif.inc');
+?>
+--FILE--
+<?php
+
+$gc_settings = [
+    [
+        'gc_probability' => -1,
+        'gc_divisor' => -1
+    ],
+    [
+        'gc_probability' => -1,
+        'gc_divisor' => 1
+    ],
+    [
+        'gc_probability' => 1,
+        'gc_divisor' => -1
+    ],
+    [
+        'gc_probability' => 1,
+        'gc_divisor' => 0
+    ],
+];
+
+ob_start();
+foreach($gc_settings as $gc_setting) {
+try {
+    session_start($gc_setting);
+    session_write_close();
+    } catch (Throwable $e) {
+        echo $e::class, ': '. $e->getMessage(), "\n";
+    }
+}
+ob_end_flush();
+?>
+Done
+--EXPECTF--
+Warning: session_start(): session.gc_probability must be greater than or equal to 0 in %s on line %d
+
+Warning: session_start(): Setting option "gc_probability" failed in %s on line %d
+
+Warning: session_start(): session.gc_divisor must be greater than 0 in %s on line %d
+
+Warning: session_start(): Setting option "gc_divisor" failed in %s on line %d
+
+Warning: session_start(): session.gc_probability must be greater than or equal to 0 in %s on line %d
+
+Warning: session_start(): Setting option "gc_probability" failed in %s on line %d
+
+Warning: session_start(): session.gc_divisor must be greater than 0 in %s on line %d
+
+Warning: session_start(): Setting option "gc_divisor" failed in %s on line %d
+
+Warning: session_start(): session.gc_divisor must be greater than 0 in %s on line %d
+
+Warning: session_start(): Setting option "gc_divisor" failed in %s on line %d
+Done