fix a use-after-free in msc_mgcp.c:_handle_error()
Move code which needs to test the mgcp_ctx->free_ctx flag upwards
such that it runs before we're calling functions which will
potentially free mgcp_ctx. The code being moved up takes effect
only in case mgcp_ctx won't be freed, so there should be no
functional difference.
Change-Id: I5df17c19e2a68c019f7eaf582b14585caa54b32a
Related: OS#2885
diff --git a/src/libmsc/msc_mgcp.c b/src/libmsc/msc_mgcp.c
index e58b249..acdb785 100644
--- a/src/libmsc/msc_mgcp.c
+++ b/src/libmsc/msc_mgcp.c
@@ -183,6 +183,16 @@
LOGPFSMLSRC(mgcp_ctx->fsm, LOGL_ERROR, file, line, "%s -- graceful shutdown...\n",
get_value_string(msc_mgcp_cause_codes_names, cause));
+ /* Request the higher layers (gsm_04_08.c) to release the call. If the
+ * problem occured after msc_mgcp_call_release() was calls, remain
+ * silent because we already got informed and the higher layers might
+ * already freed their context information (trans). */
+ if (!mgcp_ctx->free_ctx) {
+ mncc_set_cause(&mncc, GSM48_CAUSE_LOC_TRANS_NET,
+ GSM48_CC_CAUSE_RESOURCE_UNAVAIL);
+ mncc_tx_to_cc(mgcp_ctx->trans->net, MNCC_REL_REQ, &mncc);
+ }
+
/* For the shutdown we have two options. Whenever it makes sense to
* send a DLCX to the MGW in order to be sure that the connection is
* properly cleaned up, the dlcx flag should be set. In other cases
@@ -205,16 +215,6 @@
osmo_fsm_inst_state_chg(fi, ST_HALT, 0, 0);
osmo_fsm_inst_dispatch(fi, EV_TEARDOWN_ERROR, mgcp_ctx);
}
-
- /* Request the higher layers (gsm_04_08.c) to release the call. If the
- * problem occured after msc_mgcp_call_release() was calls, remain
- * silent because we already got informed and the higher layers might
- * already freed their context information (trans). */
- if (!mgcp_ctx->free_ctx) {
- mncc_set_cause(&mncc, GSM48_CAUSE_LOC_TRANS_NET,
- GSM48_CC_CAUSE_RESOURCE_UNAVAIL);
- mncc_tx_to_cc(mgcp_ctx->trans->net, MNCC_REL_REQ, &mncc);
- }
}
/* Timer callback to shut down in case of connectivity problems */