sscp_scrc: Fix memleak of xua_msg when handing it to scrc_rx_mtp_xfer_ind_xua

Fixes following error provided by LeakSanitizer:

Indirect leak of 1496 byte(s) in 11 object(s) allocated from:
    #0 0x7f1eb3332d99 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:86
    #1 0x7f1eae617b61 in _talloc_zero (/usr/lib/libtalloc.so.2+0x5b61)
    #2 0x7f1eb063e365 in xua_msg_alloc /home/pespin/dev/sysmocom/git/libosmo-sccp/src/xua_msg.c:49
    #3 0x7f1eb0650ee3 in osmo_sccp_to_xua /home/pespin/dev/sysmocom/git/libosmo-sccp/src/sccp2sua.c:1298
    #4 0x7f1eb0668d6a in mtp_user_prim_cb /home/pespin/dev/sysmocom/git/libosmo-sccp/src/sccp_user.c:173
    #5 0x7f1eb068ba86 in deliver_to_mtp_user /home/pespin/dev/sysmocom/git/libosmo-sccp/src/osmo_ss7_hmrt.c:94
    #6 0x7f1eb068bf00 in hmdt_message_for_distribution /home/pespin/dev/sysmocom/git/libosmo-sccp/src/osmo_ss7_hmrt.c:133
    #7 0x7f1eb068d345 in m3ua_hmdc_rx_from_l2 /home/pespin/dev/sysmocom/git/libosmo-sccp/src/osmo_ss7_hmrt.c:275
    #8 0x7f1eb063c08f in m3ua_rx_xfer /home/pespin/dev/sysmocom/git/libosmo-sccp/src/m3ua.c:586
    #9 0x7f1eb063cea6 in m3ua_rx_msg /home/pespin/dev/sysmocom/git/libosmo-sccp/src/m3ua.c:739
    #10 0x7f1eb0687188 in xua_cli_read_cb /home/pespin/dev/sysmocom/git/libosmo-sccp/src/osmo_ss7.c:1590
    #11 0x7f1eaff77db4 in osmo_stream_cli_read /home/pespin/dev/sysmocom/git/libosmo-netif/src/stream.c:192
    #12 0x7f1eaff79091 in osmo_stream_cli_fd_cb /home/pespin/dev/sysmocom/git/libosmo-netif/src/stream.c:276
    #13 0x7f1eaf259795 in osmo_fd_disp_fds /home/pespin/dev/sysmocom/git/libosmocore/src/select.c:217
    #14 0x7f1eaf259abb in osmo_select_main /home/pespin/dev/sysmocom/git/libosmocore/src/select.c:257
    #15 0x55666c1bebd3 in main /home/pespin/dev/sysmocom/git/osmo-msc/src/osmo-msc/msc_main.c:697
    #16 0x7f1ead1c306a in __libc_start_main (/usr/lib/libc.so.6+0x2306a)
    #17 0x55666c1bc649 in _start (/home/pespin/dev/sysmocom/build/new/out/bin/osmo-msc+0x185649)

The code path is the following, starting from mpt_user_prim_cb:
mtp_user_prim_cb
	osmo_sccp_to_xua
		xua_msg_alloc
	scrc_rx_mtp_xfer_ind_xua
		sccp_scoc_rx_from_scrc
		scrc_node_6
		scrc_node_4
		scrc_translate_node_9

So the xua_msg is created in mtp_user_prim_cb through osmo_sccp_to_xua
and then handed over to scrc_rx_mtp_xfer_ind_xua which transfers the
xua_msg and thus should take ownserhip of it, and consecuently freeing
it once it's done using it.

Change-Id: I43e159c82b64bd85b185f77ee19b6455a96e082f

1 files changed, 12 insertions, 4 deletions

diff --git a/src/sccp_scrc.c b/src/sccp_scrc.c
index cd01774..9005dc7 100644
--- a/src/sccp_scrc.c
+++ b/src/sccp_scrc.c
@@ -438,13 +438,14 @@ int sccp_scrc_rx_sclc_msg(struct osmo_sccp_instance *inst,
 }
 
 /* Figure C.1/Q.714 Sheet 1 of 12, after we converted the
- * MTP-TRANSFER.ind to SUA */
+ * MTP-TRANSFER.ind to SUA. Takes ownership of \a xua and frees it once processed. */
 int scrc_rx_mtp_xfer_ind_xua(struct osmo_sccp_instance *inst,
 			     struct xua_msg *xua)
 {
 	struct osmo_sccp_addr called;
 	uint32_t proto_class;
 	struct xua_msg_part *hop_ctr_part;
+	int rc;
 
 	LOGP(DLSS7, LOGL_DEBUG, "%s: %s\n", __func__, xua_msg_dump(xua, &xua_dialect_sua));
 	/* TODO: SCCP or nodal congestion? */
@@ -454,6 +455,7 @@ int scrc_rx_mtp_xfer_ind_xua(struct osmo_sccp_instance *inst,
 		/* Node 1 (Sheet 3) */
 		/* deliver to SCOC */
 		sccp_scoc_rx_from_scrc(inst, xua);
+		xua_msg_free(xua);
 		return 0;
 	}
 	/* We only treat connectionless and CR below */
@@ -463,7 +465,9 @@ int scrc_rx_mtp_xfer_ind_xua(struct osmo_sccp_instance *inst,
 	/* Route on GT? */
 	if (called.ri != OSMO_SCCP_RI_GT) {
 		/* Node 6 (Sheet 3) */
-		return scrc_node_6(inst, xua, &called);
+		rc = scrc_node_6(inst, xua, &called);
+		xua_msg_free(xua);
+		return rc;
 	}
 	/* Message with hop-counter? */
 	hop_ctr_part = xua_msg_find_tag(xua, SUA_IEI_S7_HOP_CTR);
@@ -472,7 +476,9 @@ int scrc_rx_mtp_xfer_ind_xua(struct osmo_sccp_instance *inst,
 		if (hop_counter <= 1) {
 			/* Error: hop-counter violation */
 			/* node 4 */
-			return scrc_node_4(inst, xua, SCCP_RETURN_CAUSE_HOP_COUNTER_VIOLATION);
+			rc = scrc_node_4(inst, xua, SCCP_RETURN_CAUSE_HOP_COUNTER_VIOLATION);
+			xua_msg_free(xua);
+			return rc;
 		}
 		/* Decrement hop-counter */
 		hop_counter--;
@@ -492,5 +498,7 @@ int scrc_rx_mtp_xfer_ind_xua(struct osmo_sccp_instance *inst,
 	default:
 		break;
 	}
-	return scrc_translate_node_9(inst, xua, &called);
+	rc = scrc_translate_node_9(inst, xua, &called);
+	xua_msg_free(xua);
+	return rc;
 }