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ext/pdo_firebird: Fix DPB stack overflow on long connection parameters #25292

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ext/pdo_firebird: Fix DPB stack overflow on long connection parameters #25292

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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 @@ -23,6 +23,10 @@ PHP NEWS
or never terminates). (Ilia Alshanetsky)
. Fixed memory leak in JIT ASSIGN_DIM when the assignment fails. (Jorg Sowa)

- PDO_Firebird:
. Fixed stack buffer overflow with long connection user names, passwords,
charsets, or roles. (Ilia Alshanetsky)

- Streams:
. Fixed bug GH-22063 (Stream filter chain UAF on self-removal during
callback). (Ilia Alshanetsky)
Expand Down
21 changes: 18 additions & 3 deletions ext/pdo_firebird/firebird_driver.c
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Expand Up @@ -1376,7 +1376,6 @@ static int pdo_firebird_handle_factory(pdo_dbh_t *dbh, zval *driver_options) /*
{ "password", NULL, 0 }
};
int i, ret = 0;
short buf_len = 256, dpb_len;

pdo_firebird_db_handle *H = dbh->driver_data = pecalloc(1,sizeof(*H),dbh->is_persistent);

Expand Down Expand Up @@ -1407,8 +1406,12 @@ static int pdo_firebird_handle_factory(pdo_dbh_t *dbh, zval *driver_options) /*
do {
static char const dpb_flags[] = {
isc_dpb_user_name, isc_dpb_password, isc_dpb_lc_ctype, isc_dpb_sql_role_name };
static char const *const dpb_names[] = { "user", "password", "charset", "role" };
char const *dpb_values[] = { dbh->username, dbh->password, vars[1].optval, vars[2].optval };
char dpb_buffer[256] = { isc_dpb_version1 }, *dpb;
size_t buf_len = sizeof(dpb_buffer) - 1;
size_t dpb_value_len;
int dpb_len;

if (EG(exception)) {
break;
Expand All @@ -1418,14 +1421,26 @@ static int pdo_firebird_handle_factory(pdo_dbh_t *dbh, zval *driver_options) /*

/* loop through all the provided arguments and set dpb fields accordingly */
for (i = 0; i < sizeof(dpb_flags); ++i) {
if (dpb_values[i] && buf_len > 0) {
dpb_len = slprintf(dpb, buf_len, "%c%c%s", dpb_flags[i], (unsigned char)strlen(dpb_values[i]),
if (dpb_values[i]) {
dpb_value_len = strlen(dpb_values[i]);
if (dpb_value_len + 2 >= buf_len) {
zend_throw_exception_ex(php_pdo_get_exception(), 0,

@ndossche ndossche Nov 8, 2026

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I wonder if it is possible to indicate which argument is too long

@iliaal iliaal Nov 8, 2026

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Done, it now names the parameter.

"Firebird database parameter \"%s\" is too long", dpb_names[i]);
break;
}
ZEND_ASSERT(dpb_value_len <= UCHAR_MAX);

dpb_len = slprintf(dpb, buf_len, "%c%c%s", dpb_flags[i], (unsigned char)dpb_value_len,
dpb_values[i]);
dpb += dpb_len;
buf_len -= dpb_len;
}
}

if (EG(exception)) {
break;
}

H->sql_dialect = PDO_FB_DIALECT;
if (vars[3].optval) {
H->sql_dialect = atoi(vars[3].optval);
Expand Down
27 changes: 27 additions & 0 deletions ext/pdo_firebird/tests/dpb_overflow.phpt
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@@ -0,0 +1,27 @@
--TEST--
PDO_Firebird rejects values that overflow the database parameter buffer
--EXTENSIONS--
pdo_firebird
--SKIPIF--
<?php require('skipif.inc'); ?>
--FILE--
<?php
require("testdb.inc");

$tests = [
'one-byte length overflow' => [str_repeat('u', 256), PDO_FIREBIRD_TEST_PASS],
'DPB capacity overflow' => [str_repeat('u', 200), str_repeat('p', 52)],
];

foreach ($tests as $description => [$username, $password]) {
try {
new PDO(PDO_FIREBIRD_TEST_DSN, $username, $password);
echo "$description: accepted\n";
} catch (PDOException $e) {
echo "$description: ", $e::class, ": ", $e->getMessage(), "\n";
}
}
?>
--EXPECT--
one-byte length overflow: PDOException: Firebird database parameter "user" is too long
DPB capacity overflow: PDOException: Firebird database parameter "password" is too long
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