From f5aaf523c58dd7bc2f57f840b717da359d08bb5c Mon Sep 17 00:00:00 2001
From: Andreas Eversberg <jolly@eversberg.eu>
Date: Thu, 20 Jun 2013 20:10:46 +0200
Subject: [PATCH] TRX: If no cipher algorithm is given, or if it is a5/0, reset
 cipher state

---
 src/osmo-bts-trx/scheduler.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/osmo-bts-trx/scheduler.c b/src/osmo-bts-trx/scheduler.c
index 9aa05390b..5a22c5c31 100644
--- a/src/osmo-bts-trx/scheduler.c
+++ b/src/osmo-bts-trx/scheduler.c
@@ -2573,7 +2573,10 @@ int trx_sched_set_cipher(struct trx_l1h *l1h, uint8_t chan_nr, int downlink,
 	int rc = -EINVAL;
 	struct trx_chan_state *chan_state;
 
-	if (algo < 0 || key_len > 8 || (algo && key_len != 8)) {
+	/* no algorithm given means a5/0 */
+	if (algo <= 0)
+		algo = 0;
+	else if (key_len != 8) {
 		LOGP(DL1C, LOGL_ERROR, "Algo A5/%d not supported with given "
 			"key len=%d\n", algo, key_len);
 		return -ENOTSUP;