From bb8990582fcbb750d71e7d38414948aed6c98524 Mon Sep 17 00:00:00 2001
From: Daniel Willmann <dwillmann@sysmocom.de>
Date: Sat, 16 Jan 2021 14:02:45 +0100
Subject: ns2: Add sanity check

Prevent memory corruption or segfaults by asserting that NSE and bind
link layer match. A mismatch should never happen and might cause the
bind to access invalid memory when sending because nsvc->priv doesn't
match what it expects.

Change-Id: I7ca4cd1c5dac8b5e44ffc4825b9373b2d04911ab
Related: OS#4948
---
 src/gb/gprs_ns2.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/gb/gprs_ns2.c b/src/gb/gprs_ns2.c
index e43b6365..3ca87a4b 100644
--- a/src/gb/gprs_ns2.c
+++ b/src/gb/gprs_ns2.c
@@ -490,6 +490,9 @@ void ns2_prim_status_ind(struct gprs_ns2_nse *nse,
 struct gprs_ns2_vc *ns2_vc_alloc(struct gprs_ns2_vc_bind *bind, struct gprs_ns2_nse *nse, bool initiater,
 				 enum gprs_ns2_vc_mode vc_mode)
 {
+	/* Sanity check */
+	OSMO_ASSERT(bind->ll == nse->ll);
+
 	struct gprs_ns2_vc *nsvc = talloc_zero(bind, struct gprs_ns2_vc);
 
 	if (!nsvc)
-- 
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