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fixeria gerrit-no-reply at lists.osmocom.orgfixeria has submitted this change. ( https://gerrit.osmocom.org/c/osmo-bsc/+/18907 )
Change subject: fix crashes due to OSMO_ASSERT(conn->lchan)
......................................................................
fix crashes due to OSMO_ASSERT(conn->lchan)
Starting from ttcn3-bsc-test-sccplite build #777, it was noticed
that osmo-bsc crashes with the following message:
Assert failed conn->lchan include/osmocom/bsc/gsm_data.h:1376
The cause of this is a recently merged patch that calls conn_get_bts() during
assignment_fsm rate counter dispatch:
"Count assignment rates per BTS as well"
commit b5ccf09fc4042c7fb1fdaaa6263961c40b32564e
Change-Id I0009e51d4caf68e762138d98e2e23d49acc3cc1a
The root cause being that the assignment_fsm attempts to count an Assignment
event for a BTS after the lchan has already been released and disassociated
from the conn.
The assertion is found in conn_get_bts(), which is used in various places. In
fact, each caller is a potential DoS risk -- though most are in code paths that
are guaranteed to have an lchan and bts present, having an OSMO_ASSERT() on the
relatively volatile presence of an lchan is not a good idea for osmo-bsc's
stability and error resilience.
- Change conn_get_bts() to return NULL in the lack of an lchan.
- Adjust all callers of conn_get_bts() to gracefully handle a NULL return val.
- Same for cgi_for_msc() and callers, closely related.
Here is a backtrace:
Program received signal SIGABRT
pwndbg> bt
0x0000555555be6e52 in conn_get_bts (conn=0x622000057160) at include/osmocom/bsc/gsm_data.h:1376
0x0000555555c1edc8 in assignment_fsm_timer_cb (fi=0x612000060220) at assignment_fsm.c:758
0x00007ffff72b1104 in fsm_tmr_cb (data=0x612000060220) at libosmocore/src/fsm.c:325
0x00007ffff72ab062 in osmo_timers_update () at libosmocore/src/timer.c:257
0x00007ffff72ab5d2 in _osmo_select_main (polling=0) at libosmocore/src/select.c:260
0x00007ffff72abd2f in osmo_select_main_ctx (polling=<optimized out>) at libosmocore/src/select.c:291
0x0000555555e1b81b in main (argc=3, argv=0x7fffffffe1b8) at osmo_bsc_main.c:953
0x00007ffff6752002 in __libc_start_main () from /usr/lib/libc.so.6
0x0000555555b61bbe in _start ()
In the case of the assignment_fsm counter, we now miss a chance to increase a
BTS counter for a failed Assignment, but this is a separate problem. The main
point of this patch is that osmo-bsc must not crash.
Related: OS#4620, OS#4619
Patch-by: fixeria
Tweaked-by: neels
Fixes: I0009e51d4caf68e762138d98e2e23d49acc3cc1a
Change-Id: Id681dfb0ad654bdb4b71805d1ad4f39a8bf6bbd1
---
M include/osmocom/bsc/gsm_data.h
M src/osmo-bsc/assignment_fsm.c
M src/osmo-bsc/bsc_vty.c
M src/osmo-bsc/gsm_08_08.c
M src/osmo-bsc/gsm_data.c
M src/osmo-bsc/osmo_bsc_bssap.c
M src/osmo-bsc/osmo_bsc_filter.c
M src/osmo-bsc/osmo_bsc_msc.c
M src/osmo-bsc/osmo_bsc_sigtran.c
9 files changed, 72 insertions(+), 25 deletions(-)
Approvals:
daniel: Looks good to me, approved
pespin: Looks good to me, but someone else must approve
Jenkins Builder: Verified
diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h
index 8c1c545..ce18d1b 100644
--- a/include/osmocom/bsc/gsm_data.h
+++ b/include/osmocom/bsc/gsm_data.h
@@ -1373,7 +1373,8 @@
static inline struct gsm_bts *conn_get_bts(struct gsm_subscriber_connection *conn) {
- OSMO_ASSERT(conn->lchan);
+ if (!conn || !conn->lchan)
+ return NULL;
return conn->lchan->ts->trx->bts;
}
diff --git a/src/osmo-bsc/assignment_fsm.c b/src/osmo-bsc/assignment_fsm.c
index 94dd359..cd5abc8 100644
--- a/src/osmo-bsc/assignment_fsm.c
+++ b/src/osmo-bsc/assignment_fsm.c
@@ -80,7 +80,8 @@
bsc_ctr_description[BSC_##counter].name, \
bsc_ctr_description[BSC_##counter].description); \
rate_ctr_inc(&conn->network->bsc_ctrs->ctr[BSC_##counter]); \
- rate_ctr_inc(&bts->bts_ctrs->ctr[BTS_##counter]); \
+ if (bts) \
+ rate_ctr_inc(&bts->bts_ctrs->ctr[BTS_##counter]); \
} while(0)
#define assignment_count_result(counter) do { \
diff --git a/src/osmo-bsc/bsc_vty.c b/src/osmo-bsc/bsc_vty.c
index 9896bff..2941e5b 100644
--- a/src/osmo-bsc/bsc_vty.c
+++ b/src/osmo-bsc/bsc_vty.c
@@ -1776,7 +1776,10 @@
/* Find the connection/lchan that we want to handover */
llist_for_each_entry(conn, &net->subscr_conns, entry) {
- if (conn_get_bts(conn)->nr == bts_nr &&
+ struct gsm_bts *bts = conn_get_bts(conn);
+ if (!bts)
+ continue;
+ if (bts->nr == bts_nr &&
conn->lchan->ts->trx->nr == trx_nr &&
conn->lchan->ts->nr == ts_nr && conn->lchan->nr == ss_nr) {
vty_out(vty, "starting %s for lchan %s...%s", action, conn->lchan->name, VTY_NEWLINE);
diff --git a/src/osmo-bsc/gsm_08_08.c b/src/osmo-bsc/gsm_08_08.c
index 3703c76..e288506 100644
--- a/src/osmo-bsc/gsm_08_08.c
+++ b/src/osmo-bsc/gsm_08_08.c
@@ -222,8 +222,9 @@
/* Has the subscriber been paged from a connected MSC? */
if (pdisc == GSM48_PDISC_RR && mtype == GSM48_MT_RR_PAG_RESP) {
subscr = bsc_subscr_find_by_mi(conn->network->bsc_subscribers, &mi);
- if (subscr) {
- msc_target = paging_get_msc(conn_get_bts(conn), subscr);
+ struct gsm_bts *bts = conn_get_bts(conn);
+ if (bts && subscr) {
+ msc_target = paging_get_msc(bts, subscr);
bsc_subscr_put(subscr);
if (is_msc_usable(msc_target, is_emerg)) {
LOG_COMPL_L3(pdisc, mtype, LOGL_DEBUG, "%s matches earlier Paging from msc %d\n",
@@ -356,6 +357,13 @@
{
struct osmo_mobile_identity mi;
struct bsc_subscr *subscr = NULL;
+ struct gsm_bts *bts = conn_get_bts(conn);
+
+ if (!bts) {
+ /* should never happen */
+ LOGP(DRSL, LOGL_ERROR, "Paging Response without lchan\n");
+ return -1;
+ }
if (osmo_mobile_identity_decode_from_l3(&mi, msg, false)) {
LOGP(DRSL, LOGL_ERROR, "Unable to extract Mobile Identity from Paging Response\n");
@@ -370,8 +378,7 @@
return -1;
}
- paging_request_stop(&conn->network->bts_list, conn_get_bts(conn), subscr, conn,
- msg);
+ paging_request_stop(&conn->network->bts_list, bts, subscr, conn, msg);
bsc_subscr_put(subscr);
return 0;
}
@@ -385,6 +392,11 @@
int8_t rc8;
struct gsm_bts *bts = conn_get_bts(conn);
+ if (!bts) {
+ /* should never happen */
+ LOGP(DRSL, LOGL_ERROR, "LU Request without lchan\n");
+ return;
+ }
if (msgb_l3len(msg) < sizeof(*gh) + sizeof(*lu)) {
LOGP(DMSC, LOGL_ERROR, "LU too small to look at: %u\n", msgb_l3len(msg));
@@ -415,6 +427,12 @@
int8_t rc8;
struct gsm_bts *bts = conn_get_bts(conn);
+ if (!bts) {
+ /* should never happen */
+ LOGP(DRSL, LOGL_ERROR, "CM Service Request without lchan\n");
+ return;
+ }
+
if (msgb_l3len(msg) < sizeof(*gh) + sizeof(*serv_req)) {
LOGP(DMSC, LOGL_ERROR, "CM Serv Req too small to look at: %u\n", msgb_l3len(msg));
return;
@@ -462,6 +480,15 @@
struct msgb *resp;
struct gsm0808_speech_codec_list scl;
int rc = -2;
+ struct gsm_bts *bts = conn_get_bts(conn);
+ struct osmo_cell_global_id *cgi = cgi_for_msc(conn->sccp.msc, bts);
+
+ if (!bts || !cgi) {
+ /* should never happen */
+ LOGP(DMSC, LOGL_ERROR, "Compl L3 without lchan\n");
+ rc = -1;
+ goto early_fail;
+ }
log_set_context(LOG_CTX_BSC_SUBSCR, conn->bsub);
@@ -482,9 +509,9 @@
bsc_scan_bts_msg(conn, msg);
if (gscon_is_aoip(conn)) {
- gen_bss_supported_codec_list(&scl, msc, conn_get_bts(conn));
+ gen_bss_supported_codec_list(&scl, msc, bts);
if (scl.len > 0)
- resp = gsm0808_create_layer3_2(msg, cgi_for_msc(conn->sccp.msc, conn_get_bts(conn)), &scl);
+ resp = gsm0808_create_layer3_2(msg, cgi, &scl);
else {
/* Note: 3GPP TS 48.008 3.2.1.32, COMPLETE LAYER 3 INFORMATION clearly states that
* Codec List (BSS Supported) shall be included, if the radio access network
@@ -492,10 +519,10 @@
* current configuration does not support any voice codecs, in those cases the
* network does not support an IP based user plane interface, and therefore the
* Codec List (BSS Supported) IE can be left out in those situations. */
- resp = gsm0808_create_layer3_2(msg, cgi_for_msc(conn->sccp.msc, conn_get_bts(conn)), NULL);
+ resp = gsm0808_create_layer3_2(msg, cgi, NULL);
}
} else
- resp = gsm0808_create_layer3_2(msg, cgi_for_msc(conn->sccp.msc, conn_get_bts(conn)), NULL);
+ resp = gsm0808_create_layer3_2(msg, cgi, NULL);
if (resp)
rc = osmo_fsm_inst_dispatch(conn->fi, GSCON_EV_A_CONN_REQ, resp);
@@ -537,6 +564,12 @@
struct msgb *resp;
struct gsm_bts *bts = conn_get_bts(conn);
+ if (!bts) {
+ /* should never happen */
+ LOGP(DMSC, LOGL_ERROR, "Classmark Update without lchan\n");
+ return;
+ }
+
rc8 = osmo_gsm48_rfpowercap2powerclass(bts->band, cm2_parsed->pwr_lev);
if (rc8 < 0) {
LOGP(DMSC, LOGL_NOTICE,
diff --git a/src/osmo-bsc/gsm_data.c b/src/osmo-bsc/gsm_data.c
index 9bf6f82..2098f13 100644
--- a/src/osmo-bsc/gsm_data.c
+++ b/src/osmo-bsc/gsm_data.c
@@ -1721,7 +1721,7 @@
/* If there's an associated lchan, attempt to update its max power to be
on track with band maximum values */
- if (conn->lchan)
+ if (bts && conn->lchan)
lchan_update_ms_power_ctrl_level(conn->lchan, bts->ms_max_power);
}
diff --git a/src/osmo-bsc/osmo_bsc_bssap.c b/src/osmo-bsc/osmo_bsc_bssap.c
index 6b225e4..2deb7f4 100644
--- a/src/osmo-bsc/osmo_bsc_bssap.c
+++ b/src/osmo-bsc/osmo_bsc_bssap.c
@@ -478,7 +478,6 @@
struct msgb *msg, unsigned int payload_length)
{
uint16_t len;
- struct gsm_network *network = NULL;
const uint8_t *data;
struct tlv_parsed tp;
struct msgb *resp;
@@ -522,7 +521,6 @@
goto reject;
}
- network = conn_get_bts(conn)->network;
data = TLVP_VAL(&tp, GSM0808_IE_ENCRYPTION_INFORMATION);
enc_bits_msc = data[0];
enc_key = &data[1];
@@ -540,10 +538,10 @@
/* The bit-mask of permitted ciphers from the MSC (sent in ASSIGNMENT COMMAND) is intersected
* with the vty-configured mask a the BSC. Finally, the best (highest) possible cipher is
* chosen. */
- chosen_cipher = select_best_cipher(enc_bits_msc, network->a5_encryption_mask);
+ chosen_cipher = select_best_cipher(enc_bits_msc, bsc_gsmnet->a5_encryption_mask);
if (chosen_cipher < 0) {
LOGP(DMSC, LOGL_ERROR, "Reject: no overlapping A5 ciphers between BSC (0x%02x) "
- "and MSC (0x%02x)\n", network->a5_encryption_mask, enc_bits_msc);
+ "and MSC (0x%02x)\n", bsc_gsmnet->a5_encryption_mask, enc_bits_msc);
reject_cause = GSM0808_CAUSE_CIPHERING_ALGORITHM_NOT_SUPPORTED;
goto reject;
}
@@ -663,17 +661,23 @@
{
int rc, i, nc = 0;
struct bsc_msc_data *msc;
+ struct gsm_bts *bts = conn_get_bts(conn);
+
+ if (!bts) {
+ LOGP(DMSC, LOGL_ERROR, "No lchan, cannot select codecs\n");
+ return -EINVAL;
+ }
msc = conn->sccp.msc;
switch (ct->ch_rate_type) {
case GSM0808_SPEECH_FULL_BM:
- rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, conn_get_bts(conn),
+ rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, bts,
RATE_PREF_FR);
nc += (rc == 0);
break;
case GSM0808_SPEECH_HALF_LM:
- rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, conn_get_bts(conn),
+ rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, bts,
RATE_PREF_HR);
nc += (rc == 0);
break;
@@ -681,19 +685,19 @@
case GSM0808_SPEECH_PERM_NO_CHANGE:
case GSM0808_SPEECH_FULL_PREF_NO_CHANGE:
case GSM0808_SPEECH_FULL_PREF:
- rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, conn_get_bts(conn),
+ rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, bts,
RATE_PREF_FR);
nc += (rc == 0);
- rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, conn_get_bts(conn),
+ rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, bts,
RATE_PREF_HR);
nc += (rc == 0);
break;
case GSM0808_SPEECH_HALF_PREF_NO_CHANGE:
case GSM0808_SPEECH_HALF_PREF:
- rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, conn_get_bts(conn),
+ rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, bts,
RATE_PREF_HR);
nc += (rc == 0);
- rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, conn_get_bts(conn),
+ rc = match_codec_pref(&req->ch_mode_rate[nc], ct, &conn->codec_list, msc, bts,
RATE_PREF_FR);
nc += (rc == 0);
break;
diff --git a/src/osmo-bsc/osmo_bsc_filter.c b/src/osmo-bsc/osmo_bsc_filter.c
index 98b5148..08c3a50 100644
--- a/src/osmo-bsc/osmo_bsc_filter.c
+++ b/src/osmo-bsc/osmo_bsc_filter.c
@@ -132,11 +132,12 @@
msc = conn->sccp.msc;
if (mtype == GSM48_MT_MM_LOC_UPD_ACCEPT) {
- if (has_core_identity(msc)) {
+ struct gsm_bts *bts = conn_get_bts(conn);
+ if (bts && has_core_identity(msc)) {
if (msgb_l3len(msg) >= sizeof(*gh) + sizeof(*lai)) {
/* overwrite LAI in the message */
lai = (struct gsm48_loc_area_id *) &gh->data[0];
- gsm48_generate_lai2(lai, bts_lai(conn_get_bts(conn)));
+ gsm48_generate_lai2(lai, bts_lai(bts));
}
}
return 0;
diff --git a/src/osmo-bsc/osmo_bsc_msc.c b/src/osmo-bsc/osmo_bsc_msc.c
index 9b00ffc..f969146 100644
--- a/src/osmo-bsc/osmo_bsc_msc.c
+++ b/src/osmo-bsc/osmo_bsc_msc.c
@@ -266,6 +266,10 @@
struct osmo_cell_global_id *cgi_for_msc(struct bsc_msc_data *msc, struct gsm_bts *bts)
{
static struct osmo_cell_global_id cgi;
+
+ if (!bts)
+ return NULL;
+
cgi.lai.plmn = msc->network->plmn;
if (msc->core_plmn.mcc != GSM_MCC_MNC_INVALID)
cgi.lai.plmn.mcc = msc->core_plmn.mcc;
diff --git a/src/osmo-bsc/osmo_bsc_sigtran.c b/src/osmo-bsc/osmo_bsc_sigtran.c
index f5489e4..43ffae0 100644
--- a/src/osmo-bsc/osmo_bsc_sigtran.c
+++ b/src/osmo-bsc/osmo_bsc_sigtran.c
@@ -311,7 +311,7 @@
return BSC_CON_REJECT_NO_LINK;
}
- if (!bsc_grace_allow_new_connection(bts->network, bts)) {
+ if (bts && !bsc_grace_allow_new_connection(bts->network, bts)) {
LOGP(DMSC, LOGL_NOTICE, "BSC in grace period. No new connections.\n");
return BSC_CON_REJECT_RF_GRACE;
}
--
To view, visit https://gerrit.osmocom.org/c/osmo-bsc/+/18907
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Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Change-Id: Id681dfb0ad654bdb4b71805d1ad4f39a8bf6bbd1
Gerrit-Change-Number: 18907
Gerrit-PatchSet: 6
Gerrit-Owner: fixeria <vyanitskiy at sysmocom.de>
Gerrit-Assignee: neels <nhofmeyr at sysmocom.de>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: daniel <dwillmann at sysmocom.de>
Gerrit-Reviewer: dexter <pmaier at sysmocom.de>
Gerrit-Reviewer: fixeria <axilirator at gmail.com>
Gerrit-Reviewer: fixeria <vyanitskiy at sysmocom.de>
Gerrit-Reviewer: laforge <laforge at osmocom.org>
Gerrit-Reviewer: pespin <pespin at sysmocom.de>
Gerrit-CC: neels <nhofmeyr at sysmocom.de>
Gerrit-MessageType: merged
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