sccp: fixup for osmo_sccp_get_ss7()

osmo_sccp_get_ss7() has the risk of a nullpointer dereference, when
sccp is NULL.

Return NULL when the sccp instance is NULL.

Add doxygen comment

Change-Id: I84d484e4441fd37443fff8c67e17df8fb15d5b2e

1 files changed, 6 insertions, 1 deletions

diff --git a/src/sccp_user.c b/src/sccp_user.c
index a4568cf..b0a807d 100644
--- a/src/sccp_user.c
+++ b/src/sccp_user.c
@@ -598,8 +598,13 @@ out_strings:
 	return NULL;
 }
 
-struct osmo_ss7_instance *osmo_sccp_get_ss7(struct osmo_sccp_instance *sccp)
+/*! \brief get the SS7 instance that is related to the given SCCP instance
+ *  \param[in] sccp SCCP instance
+ *  \returns SS7 instance; NULL if sccp was NULL */
+struct osmo_ss7_instance *osmo_sccp_get_ss7(const struct osmo_sccp_instance *sccp)
 {
+	if (!sccp)
+		return NULL;
 	return sccp->ss7;
 }