From 8e2c6a31c1401b5a6980866ef35d47eb3d8d5ca3 Mon Sep 17 00:00:00 2001 From: Neels Hofmeyr Date: Thu, 7 Mar 2019 03:06:16 +0100 Subject: use only accepted ran_conns for new transactions In connection_for_subscriber(), do not return a ran_conn that is not yet authenticated nor one that is already in release. Using a ran_conn that is not yet authenticated may cause an auth/ciph violation. Using a ran_conn that is already in release may cause a use-after-free, see OS#3842 for a description. To be paranoid, upon releasing a conn, go through the transaction freeing motions again by calling trans_conn_closed(), just in case some odd code path added another transaction while the conn was already in release. Related: OS#3842 Change-Id: Id957032e0ae1ff8ba055a75c3523447d3d06cbc3 --- src/libmsc/gsm_subscriber.c | 10 ++++++++-- src/libmsc/ran_conn.c | 4 +++- 2 files changed, 11 insertions(+), 3 deletions(-) (limited to 'src') diff --git a/src/libmsc/gsm_subscriber.c b/src/libmsc/gsm_subscriber.c index e60344fec..c4faa948c 100644 --- a/src/libmsc/gsm_subscriber.c +++ b/src/libmsc/gsm_subscriber.c @@ -200,8 +200,14 @@ struct ran_conn *connection_for_subscr(struct vlr_subscr *vsub) struct ran_conn *conn; llist_for_each_entry(conn, &net->ran_conns, entry) { - if (conn->vsub == vsub) - return conn; + if (conn->vsub != vsub) + continue; + /* Found a conn, but is it in a usable state? Must not add transactions to a conn that is in release, + * and must not start transactions for an unauthenticated subscriber. There will obviously be only one + * conn for this vsub, so return NULL right away. */ + if (!ran_conn_is_accepted(conn)) + return NULL; + return conn; } return NULL; diff --git a/src/libmsc/ran_conn.c b/src/libmsc/ran_conn.c index 79709c63a..e54e542b9 100644 --- a/src/libmsc/ran_conn.c +++ b/src/libmsc/ran_conn.c @@ -538,8 +538,10 @@ static void ran_conn_fsm_cleanup(struct osmo_fsm_inst *fi, enum osmo_fsm_term_ca { struct ran_conn *conn = fi->priv; - if (ran_conn_fsm_has_active_transactions(fi)) + if (ran_conn_fsm_has_active_transactions(fi)) { LOGPFSML(fi, LOGL_ERROR, "Deallocating despite active transactions\n"); + trans_conn_closed(conn); + } if (!conn) { LOGP(DRLL, LOGL_ERROR, "Freeing NULL RAN connection\n"); -- cgit v1.2.3