neels has uploaded this change for review.

View Change

CM Serv Rej: do not crash on use count mismatch

We may issue a CM Service Reject also in obscure situations, where no CM
Service Request was permitted. In those cases, there will be no use
count. Do not crash then, just don't decrement.

Related: OS#5532
Change-Id: I2009df42d1f27ec0d011e22bfc46dbc17afe7239
---
M src/libmsc/gsm_04_08.c
1 file changed, 8 insertions(+), 1 deletion(-)

git pull ssh://gerrit.osmocom.org:29418/osmo-msc refs/changes/16/27916/1

diff --git a/src/libmsc/gsm_04_08.c b/src/libmsc/gsm_04_08.c
index b5d46fd..0983295 100644
--- a/src/libmsc/gsm_04_08.c
+++ b/src/libmsc/gsm_04_08.c
@@ -1513,8 +1513,15 @@
 				  enum gsm48_reject_value cause)
 {
 	struct msc_a *msc_a = msc_conn_ref;
+	const char *use_token;
 	msc_gsm48_tx_mm_serv_rej(msc_a, cause);
-	msc_a_put(msc_a, msc_a_cm_service_type_to_use(cm_service_type));
+
+	/* Normally, there is a use count to be removed by the CM Service Reject.
+	 * There has been a report though of an error situation (OS#5532) where no use count remains to be removed here.
+	 * In that case, do not crash osmo-msc, just don't decrement it. */
+	use_token = msc_a_cm_service_type_to_use(cm_service_type);
+	if (osmo_use_count_by(&msc_a->use_count, use_token))
+		msc_a_put(msc_a, use_token);
 	return 0;
 }
 

To view, visit change 27916. To unsubscribe, or for help writing mail filters, visit settings.