From 14e043fbcfcfbafd8088bf65c74ad916c1bba755 Mon Sep 17 00:00:00 2001
From: Neels Hofmeyr <neels@hofmeyr.de>
Date: Sun, 13 Jun 2021 18:12:39 +0200
Subject: [PATCH] rsl_data_request() check lchan pointer before access

fixup for commit 43aeeaf05ad814ccab0e93227b1248a20302c8ec
'RSL chan_nr: replace OSMO_ASSERT with error handling'
I71ed6437c403a3f9336e17a94b4948fca295d853

Related: CID#236319
Related: SYS#5315 OS#4940
Change-Id: I873c1a27f9449a56c525984ea50bfcf6daa4b5f8
---
 src/osmo-bsc/abis_rsl.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/osmo-bsc/abis_rsl.c b/src/osmo-bsc/abis_rsl.c
index ac8006d33..7525e310c 100644
--- a/src/osmo-bsc/abis_rsl.c
+++ b/src/osmo-bsc/abis_rsl.c
@@ -939,11 +939,7 @@ int rsl_siemens_mrpci(struct gsm_lchan *lchan, struct rsl_mrpci *mrpci)
 /* Chapter 8.3.1 */
 int rsl_data_request(struct msgb *msg, uint8_t link_id)
 {
-	int chan_nr = gsm_lchan2chan_nr(msg->lchan, true);
-	if (chan_nr < 0) {
-		msgb_free(msg);
-		return chan_nr;
-	}
+	int chan_nr;
 
 	if (msg->lchan == NULL) {
 		LOGP(DRSL, LOGL_ERROR, "cannot send DATA REQUEST to unknown lchan\n");
@@ -951,6 +947,12 @@ int rsl_data_request(struct msgb *msg, uint8_t link_id)
 		return -EINVAL;
 	}
 
+	chan_nr = gsm_lchan2chan_nr(msg->lchan, true);
+	if (chan_nr < 0) {
+		msgb_free(msg);
+		return chan_nr;
+	}
+
 	rsl_rll_push_l3(msg, RSL_MT_DATA_REQ, chan_nr, link_id, 1);
 
 	msg->dst = rsl_chan_link(msg->lchan);