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Fix leak when persistent PDO liveness check fails #23249

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Fix leak when persistent PDO liveness check fails #23249

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4 changes: 4 additions & 0 deletions NEWS
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,10 @@ PHP NEWS
. Fixed bug GH-15375 (Nested "yield from" skips items after a valid() or
next() call on the inner generator). (iliaal)

- PDO:
. Fixed a leak when a persistent connection failed a liveness check
with no other live PDO handle. (iliaal)

27 Aug 2026, PHP 8.4.25

- Core:
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9 changes: 6 additions & 3 deletions ext/pdo/pdo_dbh.c
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Expand Up @@ -411,9 +411,12 @@ PDO_API void php_pdo_internal_construct_driver(INTERNAL_FUNCTION_PARAMETERS, zen

/* is the connection still alive ? */
if (pdbh->methods->check_liveness && FAILURE == (pdbh->methods->check_liveness)(pdbh)) {
/* nope... need to kill it */
pdbh->refcount--;
zend_list_close(le);
if (pdbh->refcount > 1) {
pdbh->refcount--;
zend_list_close(le);
} else {
zend_hash_str_del(&EG(persistent_list), hashkey, plen);
}
pdbh = NULL;
}
}
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34 changes: 34 additions & 0 deletions ext/pdo_mysql/tests/persistent_liveness_evict.phpt
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@@ -0,0 +1,34 @@
--TEST--
Persistent reconnect after a dead cached handle does not leak the old pdo_dbh_t
--EXTENSIONS--
pdo_mysql
--SKIPIF--
<?php
require_once __DIR__ . '/inc/mysql_pdo_test.inc';
MySQLPDOTest::skip();
?>
--FILE--
<?php
require_once __DIR__ . '/inc/mysql_pdo_test.inc';

$dsn = MySQLPDOTest::getDSN();
$user = PDO_MYSQL_TEST_USER;
$pass = PDO_MYSQL_TEST_PASS;
$opts = [
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
PDO::ATTR_PERSISTENT => true,
];

$cached = new PDO($dsn, $user, $pass, $opts);
$id = (int) $cached->query('SELECT CONNECTION_ID()')->fetchColumn();
unset($cached);

$killer = new PDO($dsn, $user, $pass, [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]);
$killer->exec('KILL ' . $id);
unset($killer);

$next = new PDO($dsn, $user, $pass, $opts);
echo $next->query('SELECT 1')->fetchColumn(), "\n";
?>
--EXPECT--
1

@kamil-tekiela kamil-tekiela Aug 13, 2026

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So how does this test check for the leak?

@iliaal iliaal Aug 14, 2026

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It triggers the dead-handle reconnect. The leaked handle is pecalloc, so you only see it under valgrind or LSAN, not in --EXPECT--.

@kamil-tekiela kamil-tekiela Aug 14, 2026

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image Does it depend on some configuration data?

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