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[mysqlnd] Fix result set field metadata length buffer over-read #23496

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[mysqlnd] Fix result set field metadata length buffer over-read #23496

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44 changes: 44 additions & 0 deletions ext/mysqli/tests/fake_server.inc
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Original file line number Diff line number Diff line change
Expand Up @@ -816,6 +816,50 @@ function my_mysqli_test_stmt_response_row_read_two_fields(my_mysqli_fake_server_
}
}

function my_mysqli_test_rset_field_metadata_len_over_read(my_mysqli_fake_server_conn $conn): void
{
$rh = $conn->packet_generator->server_tabular_query_response();

$qr2 = new my_mysqli_fake_packet();
$qr2->packet_length = "0c0000";
$qr2->packet_number = "02";
$qr2->catalog_length_plus_name = "0161";
$qr2->db_length_plus_name = "0162";
$qr2->table_length_plus_name = "0163";
$qr2->original_t = "0164";
$qr2->name_length_plus_name = "0165";
$qr2->original_n = "fcff";

$conn->send_server_greetings();
$conn->read_packets(1);
$conn->send_server_ok();
$conn->read_packets(1);
$conn->send($conn->packets_to_bytes([$rh[0], $qr2]), "Malicious Tabular Response [metadata string length past the packet size]");
$conn->read();
}

function my_mysqli_test_rset_field_metadata_len_past_packet(my_mysqli_fake_server_conn $conn): void
{
$rh = $conn->packet_generator->server_tabular_query_response();

$qr2 = new my_mysqli_fake_packet();
$qr2->packet_length = "0c0000";
$qr2->packet_number = "02";
$qr2->catalog_length_plus_name = "0161";
$qr2->db_length_plus_name = "0162";
$qr2->table_length_plus_name = "0163";
$qr2->original_t = "0164";
$qr2->name_length_plus_name = "0165";
$qr2->original_n = "0561";

$conn->send_server_greetings();
$conn->read_packets(1);
$conn->send_server_ok();
$conn->read_packets(1);
$conn->send($conn->packets_to_bytes([$rh[0], $qr2]), "Malicious Tabular Response [metadata string length past the packet size]");
$conn->read();
}

function my_mysqli_test_query_response_row_length_overflow(my_mysqli_fake_server_conn $conn): void
{
$rh = $conn->packet_generator->server_query_execute_data_response('strval');
Expand Down
42 changes: 42 additions & 0 deletions ext/mysqli/tests/mysqlnd_rset_field_len_over_read.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,42 @@
--TEST--
mysqlnd result set field metadata string length buffer over-read (len clamped to packet size)
--EXTENSIONS--
mysqli
--FILE--
<?php
require_once 'fake_server.inc';

$servername = "127.0.0.1";
$username = "root";
$password = "";

$process = run_fake_server_in_background('rset_field_metadata_len_over_read');
$process->wait();

try {
$conn = new mysqli( $servername, $username, $password, "", $process->getPort());
var_dump($conn->query("SELECT * from users"));
} catch (Exception $e) {
echo $e::class, ": ", $e->getMessage(), PHP_EOL;
}

$conn->close();

$process->terminate();

print "done!";
?>
--EXPECTF--
[*] Server started on 127.0.0.1:%d
[*] Connection established
[*] Sending - Server Greeting: 580000000a352e352e352d31302e352e31382d4d6172696144420003000000473e3f6047257c6700fef7080200ff81150000000000000f0000006c6b55463f49335f686c6431006d7973716c5f6e61746976655f70617373776f7264
[*] Received: %s
[*] Sending - Server OK: 0700000200000002000000
[*] Received: %s
[*] Sending - Malicious Tabular Response [metadata string length past the packet size]: 01000001010c00000201610162016301640165fcff

Warning: mysqli::query(): Premature end of data (mysqlnd_wireprotocol.c:%d) in %s on line %d

Warning: mysqli::query(): Result set field packet %d bytes shorter than expected in %s on line %d
bool(false)
done!
40 changes: 40 additions & 0 deletions ext/mysqli/tests/mysqlnd_rset_field_len_past_packet.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,40 @@
--TEST--
mysqlnd result set field metadata string length exceeds remaining packet bytes
--EXTENSIONS--
mysqli
--FILE--
<?php
require_once 'fake_server.inc';

$servername = "127.0.0.1";
$username = "root";
$password = "";

$process = run_fake_server_in_background('rset_field_metadata_len_past_packet');
$process->wait();

try {
$conn = new mysqli( $servername, $username, $password, "", $process->getPort());
var_dump($conn->query("SELECT * from users"));
} catch (Exception $e) {
echo $e::class, ": ", $e->getMessage(), PHP_EOL;
}

$conn->close();

$process->terminate();

print "done!";
?>
--EXPECTF--
[*] Server started on 127.0.0.1:%d
[*] Connection established
[*] Sending - Server Greeting: %s
[*] Received: %s
[*] Sending - Server OK: %s
[*] Received: %s
[*] Sending - Malicious Tabular Response [metadata string length past the packet size]: %s

Warning: mysqli::query(): Result set field metadata string length is past the packet size in %s on line %d
bool(false)
done!
9 changes: 8 additions & 1 deletion ext/mysqlnd/mysqlnd_wireprotocol.c
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Expand Up @@ -1171,10 +1171,17 @@ void php_mysqlnd_rset_header_free_mem(void * _packet)
/* }}} */

#define READ_RSET_FIELD(field_name) do { \
BAIL_IF_NO_MORE_DATA; \
len = php_mysqlnd_net_field_length(&p); \
if (UNEXPECTED(len == MYSQLND_NULL_LENGTH)) { \
goto faulty_or_fake; \
} else if (len != 0) { \
BAIL_IF_NO_MORE_DATA; \
if (UNEXPECTED((p - begin) > packet->header.size || packet->header.size - (p - begin) < len)) { \
DBG_ERR_FMT("Result set field metadata string length is past the packet size"); \
php_error_docref(NULL, E_WARNING, "Result set field metadata string length is past the packet size"); \
DBG_RETURN(FAIL); \
} \
Comment on lines +1179 to +1184

@kamil-tekiela kamil-tekiela Aug 29, 2026

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Suggested change
BAIL_IF_NO_MORE_DATA; \
if (UNEXPECTED(len > (zend_ulong)(packet->header.size - (size_t)(p - begin)))) { \
goto premature_end; \
} \
BAIL_IF_NO_MORE_DATA; \
if (UNEXPECTED(len > (zend_ulong)(packet->header.size - (size_t)(p - begin)))) { \
php_error_docref(NULL, E_WARNING, "Result set field metadata string length is past the packet size"); \
DBG_RETURN(FAIL); \
} \

This part is untested, but if there was a test the value in the test would underflow, so it's probably better to do it how we do it on line 740. Also, on line 740 we don't do (zend_ulong) cast so I think that's redundant too, but I am not sure.

@iliaal iliaal Aug 29, 2026

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Matched the line 740 check and warning. goto premature_end underflows the reported size when p is still inside the packet; added mysqlnd_rset_field_len_past_packet.phpt for that.

meta->field_name = (const char *)p; \
meta->field_name ## _length = len; \
p += len; \
Expand Down Expand Up @@ -1243,7 +1250,7 @@ php_mysqlnd_rset_field_read(MYSQLND_CONN_DATA * conn, void * _packet)
READ_RSET_FIELD(name);
READ_RSET_FIELD(org_name);

/* 1 byte length */
BAIL_IF_NO_MORE_DATA;
if (UNEXPECTED(12 != *p)) {
DBG_ERR_FMT("Protocol error. Server sent false length. Expected 12 got %d", (int) *p);
php_error_docref(NULL, E_WARNING, "Protocol error. Server sent false length. Expected 12");
Expand Down
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