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Fix GH-16959: snmpget modifies the object_id (as array).
Instead of modifying the zval, we use the zend_try_get_string. close GH-16969
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3 files changed

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-20
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3 files changed

+133
-20
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‎NEWS

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -67,6 +67,10 @@ PHP NEWS
6767
. Fixed bug GH-16808 (Segmentation fault in RecursiveIteratorIterator
6868
->current() with a xml element input). (nielsdos)
6969

70+
- SNMP:
71+
. Fixed bug GH-16959 (snmget modifies the object_id array).
72+
(David Carlier)
73+
7074
- Standard:
7175
. Fixed bug GH-16905 (Internal iterator functions can't handle UNDEF
7276
properties). (nielsdos)

‎ext/snmp/snmp.c

Lines changed: 60 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -626,6 +626,31 @@ static void php_snmp_internal(INTERNAL_FUNCTION_PARAMETERS, int st,
626626
}
627627
/* }}} */
628628

629+
static void php_snmp_zend_string_release_from_char_pointer(char *ptr) {
630+
if (ptr) {
631+
zend_string *pptr = (zend_string *)(ptr - XtOffsetOf(zend_string, val));
632+
zend_string_release(pptr);
633+
}
634+
}
635+
636+
static void php_free_objid_query(struct objid_query *objid_query, HashTable* oid_ht, const HashTable *value_ht, int st) {
637+
if (oid_ht) {
638+
uint32_t count = zend_hash_num_elements(oid_ht);
639+
640+
for (uint32_t i = 0; i < count; i ++) {
641+
snmpobjarg *arg = &objid_query->vars[i];
642+
if (!arg->oid) {
643+
break;
644+
}
645+
if (value_ht) {
646+
php_snmp_zend_string_release_from_char_pointer(arg->value);
647+
}
648+
php_snmp_zend_string_release_from_char_pointer(arg->oid);
649+
}
650+
}
651+
efree(objid_query->vars);
652+
}
653+
629654
/* {{{ php_snmp_parse_oid
630655
*
631656
* OID parser (and type, value for SNMP_SET command)
@@ -674,10 +699,15 @@ static bool php_snmp_parse_oid(
674699
return false;
675700
}
676701
objid_query->vars = (snmpobjarg *)safe_emalloc(sizeof(snmpobjarg), zend_hash_num_elements(oid_ht), 0);
702+
memset(objid_query->vars, 0, sizeof(snmpobjarg) * zend_hash_num_elements(oid_ht));
677703
objid_query->array_output = (st & SNMP_CMD_SET) == 0;
678704
ZEND_HASH_FOREACH_VAL(oid_ht, tmp_oid) {
679-
convert_to_string(tmp_oid);
680-
objid_query->vars[objid_query->count].oid = Z_STRVAL_P(tmp_oid);
705+
zend_string *tmp = zval_try_get_string(tmp_oid);
706+
if (!tmp) {
707+
php_free_objid_query(objid_query, oid_ht, value_ht, st);
708+
return false;
709+
}
710+
objid_query->vars[objid_query->count].oid = ZSTR_VAL(tmp);
681711
if (st & SNMP_CMD_SET) {
682712
if (type_str) {
683713
pptr = ZSTR_VAL(type_str);
@@ -701,18 +731,24 @@ static bool php_snmp_parse_oid(
701731
}
702732
}
703733
if (idx_type < type_ht->nNumUsed) {
704-
convert_to_string(tmp_type);
705-
if (Z_STRLEN_P(tmp_type) != 1) {
734+
zend_string *type = zval_try_get_string(tmp_type);
735+
if (!type) {
736+
php_free_objid_query(objid_query, oid_ht, value_ht, st);
737+
return false;
738+
}
739+
size_t len = ZSTR_LEN(type);
740+
char ptype = *ZSTR_VAL(type);
741+
zend_string_release(type);
742+
if (len != 1) {
706743
zend_value_error("Type must be a single character");
707-
efree(objid_query->vars);
744+
php_free_objid_query(objid_query, oid_ht, value_ht, st);
708745
return false;
709746
}
710-
pptr = Z_STRVAL_P(tmp_type);
711-
objid_query->vars[objid_query->count].type = *pptr;
747+
objid_query->vars[objid_query->count].type = ptype;
712748
idx_type++;
713749
} else {
714-
php_error_docref(NULL, E_WARNING, "'%s': no type set", Z_STRVAL_P(tmp_oid));
715-
efree(objid_query->vars);
750+
php_error_docref(NULL, E_WARNING, "'%s': no type set", ZSTR_VAL(tmp));
751+
php_free_objid_query(objid_query, oid_ht, value_ht, st);
716752
return false;
717753
}
718754
}
@@ -738,12 +774,16 @@ static bool php_snmp_parse_oid(
738774
}
739775
}
740776
if (idx_value < value_ht->nNumUsed) {
741-
convert_to_string(tmp_value);
742-
objid_query->vars[objid_query->count].value = Z_STRVAL_P(tmp_value);
777+
zend_string *tmp = zval_try_get_string(tmp_value);
778+
if (!tmp) {
779+
php_free_objid_query(objid_query, oid_ht, value_ht, st);
780+
return false;
781+
}
782+
objid_query->vars[objid_query->count].value = ZSTR_VAL(tmp);
743783
idx_value++;
744784
} else {
745-
php_error_docref(NULL, E_WARNING, "'%s': no value set", Z_STRVAL_P(tmp_oid));
746-
efree(objid_query->vars);
785+
php_error_docref(NULL, E_WARNING, "'%s': no value set", ZSTR_VAL(tmp));
786+
php_free_objid_query(objid_query, oid_ht, value_ht, st);
747787
return false;
748788
}
749789
}
@@ -756,14 +796,14 @@ static bool php_snmp_parse_oid(
756796
if (st & SNMP_CMD_WALK) {
757797
if (objid_query->count > 1) {
758798
php_snmp_error(object, PHP_SNMP_ERRNO_OID_PARSING_ERROR, "Multi OID walks are not supported!");
759-
efree(objid_query->vars);
799+
php_free_objid_query(objid_query, oid_ht, value_ht, st);
760800
return false;
761801
}
762802
objid_query->vars[0].name_length = MAX_NAME_LEN;
763803
if (strlen(objid_query->vars[0].oid)) { /* on a walk, an empty string means top of tree - no error */
764804
if (!snmp_parse_oid(objid_query->vars[0].oid, objid_query->vars[0].name, &(objid_query->vars[0].name_length))) {
765805
php_snmp_error(object, PHP_SNMP_ERRNO_OID_PARSING_ERROR, "Invalid object identifier: %s", objid_query->vars[0].oid);
766-
efree(objid_query->vars);
806+
php_free_objid_query(objid_query, oid_ht, value_ht, st);
767807
return false;
768808
}
769809
} else {
@@ -775,7 +815,7 @@ static bool php_snmp_parse_oid(
775815
objid_query->vars[objid_query->offset].name_length = MAX_OID_LEN;
776816
if (!snmp_parse_oid(objid_query->vars[objid_query->offset].oid, objid_query->vars[objid_query->offset].name, &(objid_query->vars[objid_query->offset].name_length))) {
777817
php_snmp_error(object, PHP_SNMP_ERRNO_OID_PARSING_ERROR, "Invalid object identifier: %s", objid_query->vars[objid_query->offset].oid);
778-
efree(objid_query->vars);
818+
php_free_objid_query(objid_query, oid_ht, value_ht, st);
779819
return false;
780820
}
781821
}
@@ -1252,12 +1292,12 @@ static void php_snmp(INTERNAL_FUNCTION_PARAMETERS, int st, int version)
12521292

12531293
if (session_less_mode) {
12541294
if (!netsnmp_session_init(&session, version, a1, a2, timeout, retries)) {
1255-
efree(objid_query.vars);
1295+
php_free_objid_query(&objid_query, oid_ht, value_ht, st);
12561296
netsnmp_session_free(&session);
12571297
RETURN_FALSE;
12581298
}
12591299
if (version == SNMP_VERSION_3 && !netsnmp_session_set_security(session, a3, a4, a5, a6, a7, NULL, NULL)) {
1260-
efree(objid_query.vars);
1300+
php_free_objid_query(&objid_query, oid_ht, value_ht, st);
12611301
netsnmp_session_free(&session);
12621302
/* Warning message sent already, just bail out */
12631303
RETURN_FALSE;
@@ -1268,7 +1308,7 @@ static void php_snmp(INTERNAL_FUNCTION_PARAMETERS, int st, int version)
12681308
session = snmp_object->session;
12691309
if (!session) {
12701310
zend_throw_error(NULL, "Invalid or uninitialized SNMP object");
1271-
efree(objid_query.vars);
1311+
php_free_objid_query(&objid_query, oid_ht, value_ht, st);
12721312
RETURN_THROWS();
12731313
}
12741314

@@ -1294,7 +1334,7 @@ static void php_snmp(INTERNAL_FUNCTION_PARAMETERS, int st, int version)
12941334

12951335
php_snmp_internal(INTERNAL_FUNCTION_PARAM_PASSTHRU, st, session, &objid_query);
12961336

1297-
efree(objid_query.vars);
1337+
php_free_objid_query(&objid_query, oid_ht, value_ht, st);
12981338

12991339
if (session_less_mode) {
13001340
netsnmp_session_free(&session);

‎ext/snmp/tests/gh16959.phpt

Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
1+
--TEST--
2+
snmpget() modifies object_id array source
3+
--EXTENSIONS--
4+
snmp
5+
--SKIPIF--
6+
<?php
7+
require_once(__DIR__.'/skipif.inc');
8+
?>
9+
--FILE--
10+
<?php
11+
require_once(__DIR__.'/snmp_include.inc');
12+
13+
$bad_object_ids = array (
14+
077 => 077, -066 => -066, -0345 => -0345, 0 => 0
15+
);
16+
var_dump($bad_object_ids);
17+
var_dump(snmpget($hostname, "", $bad_object_ids) === false);
18+
// The array should remain unmodified
19+
var_dump($bad_object_ids);
20+
try {
21+
snmpget($hostname, "", [0 => new stdClass()]);
22+
} catch (Throwable $e) {
23+
echo $e->getMessage() . PHP_EOL;
24+
}
25+
26+
try {
27+
snmp2_set($hostname, $communityWrite, $bad_object_ids, array(new stdClass()), array(null));
28+
} catch (Throwable $e) {
29+
echo $e->getMessage() . PHP_EOL;
30+
}
31+
try {
32+
snmp2_set($hostname, $communityWrite, $bad_object_ids, array("toolongtype"), array(null));
33+
} catch (Throwable $e) {
34+
echo $e->getMessage() . PHP_EOL;
35+
}
36+
try {
37+
snmp2_set($hostname, $communityWrite, $bad_object_ids, array(str_repeat("onetoomuch", random_int(1, 1))), array(null));
38+
} catch (Throwable $e) {
39+
echo $e->getMessage();
40+
}
41+
?>
42+
--EXPECTF--
43+
array(4) {
44+
[63]=>
45+
int(63)
46+
[-54]=>
47+
int(-54)
48+
[-229]=>
49+
int(-229)
50+
[0]=>
51+
int(0)
52+
}
53+
54+
Warning: snmpget(): Invalid object identifier: -54 in %s on line %d
55+
bool(true)
56+
array(4) {
57+
[63]=>
58+
int(63)
59+
[-54]=>
60+
int(-54)
61+
[-229]=>
62+
int(-229)
63+
[0]=>
64+
int(0)
65+
}
66+
Object of class stdClass could not be converted to string
67+
Object of class stdClass could not be converted to string
68+
Type must be a single character
69+
Type must be a single character

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