[PATCH] openbsc[master]: gsm0408_rcv_cc: guard against NULL subscriber

[Neels Hofmeyr]

Review at  https://gerrit.osmocom.org/1662

gsm0408_rcv_cc: guard against NULL subscriber

Check conn->subscr against NULL.

gsm0408_rcv_cc() dereferences many conn members without checking presence: the
bts and lchan members may be expected to be NULL in the ongoing MSC split and
3G developments.

But the conn->subscr is initially NULL, so an MS sending a CC message before
something like a LU or CM Service Request will result in a segfault. Prevent
that.

Note: the upcoming VLR will be more restrictive on what messages are processed,
this is a "backport" to the situation on current master.

Change-Id: If067db7cc0dd3210d9eb1da15be6b637795a3ecf
---
M openbsc/src/libmsc/gsm_04_08.c
1 file changed, 5 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/openbsc refs/changes/62/1662/1

diff --git a/openbsc/src/libmsc/gsm_04_08.c b/openbsc/src/libmsc/gsm_04_08.c
index 742f803..755aa79 100644
--- a/openbsc/src/libmsc/gsm_04_08.c
+++ b/openbsc/src/libmsc/gsm_04_08.c
@@ -3605,6 +3605,11 @@
 		return -EINVAL;
 	}
 
+	if (!conn->subscr) {
+		LOGP(DCC, LOGL_ERROR, "Invalid conn, no subscriber\n");
+		return -EINVAL;
+	}
+
 	/* Find transaction */
 	trans = trans_find_by_id(conn, GSM48_PDISC_CC, transaction_id);
 

-- 
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Gerrit-MessageType: newchange
Gerrit-Change-Id: If067db7cc0dd3210d9eb1da15be6b637795a3ecf
Gerrit-PatchSet: 1
Gerrit-Project: openbsc
Gerrit-Branch: master
Gerrit-Owner: Neels Hofmeyr <nhofmeyr at sysmocom.de>