From e51a0b53fc1c34291bdf8af0e64d93ae1af6b66b Mon Sep 17 00:00:00 2001 From: Neels Hofmeyr Date: Thu, 14 Mar 2019 23:48:27 +0100 Subject: avoid use-after-free: on MGW endpoint dealloc, also forget it in conn->ho.* With the FORGET_MGW_ENDPOINT event, the MGW endpoint FSM notifies the gscon that it has deallocated and that hence the gscon should forget all references to it (to avoid a use-after-free). Also do this for the endpoint FSM and endpoint ci pointers in the conn->ho.* sub struct. I saw a use-after-free after a Handover Failure message tears down the lchan and MGW endpoint before triggering the handover_fsm.c cleanup code, which also tries to clean up an endpoint CI if it was created for the failed Handover. Change-Id: I6702ccd0df44bea5eb8b26d471d7903c24e6e30b --- src/osmo-bsc/bsc_subscr_conn_fsm.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'src') diff --git a/src/osmo-bsc/bsc_subscr_conn_fsm.c b/src/osmo-bsc/bsc_subscr_conn_fsm.c index 13a573021..1cc0c78b4 100644 --- a/src/osmo-bsc/bsc_subscr_conn_fsm.c +++ b/src/osmo-bsc/bsc_subscr_conn_fsm.c @@ -699,6 +699,7 @@ static void gscon_forget_mgw_endpoint(struct gsm_subscriber_connection *conn) { conn->user_plane.mgw_endpoint = NULL; conn->user_plane.mgw_endpoint_ci_msc = NULL; + conn->ho.created_ci_for_msc = NULL; lchan_forget_mgw_endpoint(conn->lchan); lchan_forget_mgw_endpoint(conn->assignment.new_lchan); lchan_forget_mgw_endpoint(conn->ho.new_lchan); @@ -706,9 +707,11 @@ static void gscon_forget_mgw_endpoint(struct gsm_subscriber_connection *conn) void gscon_forget_mgw_endpoint_ci(struct gsm_subscriber_connection *conn, struct mgwep_ci *ci) { - if (ci != conn->user_plane.mgw_endpoint_ci_msc) - return; - conn->user_plane.mgw_endpoint_ci_msc = NULL; + if (conn->ho.created_ci_for_msc == ci) + conn->ho.created_ci_for_msc = NULL; + + if (conn->user_plane.mgw_endpoint_ci_msc == ci) + conn->user_plane.mgw_endpoint_ci_msc = NULL; } static void gscon_fsm_allstate(struct osmo_fsm_inst *fi, uint32_t event, void *data) -- cgit v1.2.3