From 8c7d2590611eba7a0c0a8e27cc9c4cbf1b5a6067 Mon Sep 17 00:00:00 2001 From: Pau Espin Pedrol Date: Mon, 9 Jul 2018 20:44:17 +0200 Subject: Disarm T3395 when dettaching mmctx from pdpctx In sgsn_pdp_ctx_terminate, a pdp ctx is terminated and the mm ctx is detached. However, T3395 may still be armed and then pdpctx_timer_cb will trigger, and attempt to use the pdp->mm ctx which was already detached (set to NULL) when calling gsm48_tx_gsm_deact_pdp_req()->mmctx2msgid(). Following list of log lines shows the scenario+crash, in which osmo-sgsn is trying to deactivate the ctx all the time but the PCU doesn't ACK it, and then at some point the PDP context is forced released. osmo-sgsn/src/gprs/gprs_gmm.c:2294 MM(901700000015254/d7e9ab95) <- DEACTIVATE PDP CONTEXT REQ osmo-sgsn/src/gprs/gprs_gmm.c:1464 MM(901700000015254/d7e9ab95) -> GMM DETACH REQUEST TLLI=0xd7e9ab95 type=GPRS detach Power-off osmo-sgsn/src/gprs/gprs_gmm.c:313 MM(901700000015254/d7e9ab95) Cleaning MM context due to GPRS DETACH REQUEST osmo-sgsn/src/gprs/gprs_sgsn.c:332 MM(901700000015254/d7e9ab95) Dropping PDP context for NSAPI=5 osmo-sgsn/src/gprs/gprs_sgsn.c:434 PDP(901700000015254/0) Forcing release of PDP context osmo-sgsn/src/gprs/gprs_sndcp.c:508 SNSM-DEACTIVATE.ind (lle=0x62100001bca0, TLLI=d7e9ab95, SAPI=3, NSAPI=5) osmo-sgsn/src/gprs/sgsn_libgtp.c:310 PDP(---/0) Delete PDP Context osmo-sgsn/src/gprs/gprs_gmm.c:2294 MM(---/ffffffff) <- DEACTIVATE PDP CONTEXT REQ osmo-sgsn/src/gprs/gprs_gmm.c:305:25: runtime error: member access within null pointer of type 'const struct sgsn_mm_ctx' Program received signal SIGSEGV, Segmentation fault. 0x0000555555698c1b in mmctx2msgid (msg=0x61d0000172e0, mm=0x0) at /home/pespin/dev/sysmocom/git/osmo-sgsn/src/gprs/gprs_gmm.c:305 305 msgb_tlli(msg) = mm->gb.tlli; (gdb) bt #0 0x0000555555698c1b in mmctx2msgid (msg=0x61d0000172e0, mm=0x0) at osmo-sgsn/src/gprs/gprs_gmm.c:305 #1 0x00005555556b170a in _gsm48_tx_gsm_deact_pdp_req (mm=0x0, tid=0 '\000', sm_cause=38 '&') at osmo-sgsn/src/gprs/gprs_gmm.c:2297 #2 0x00005555556b1a2e in gsm48_tx_gsm_deact_pdp_req (pdp=0x6140000008a0, sm_cause=38 '&') at osmo-sgsn/src/gprs/gprs_gmm.c:2311 #3 0x00005555556b876c in pdpctx_timer_cb (_pdp=0x6140000008a0) at osmo-sgsn/src/gprs/gprs_gmm.c:2717 #4 0x00007ffff355eb3e in osmo_timers_update () at libosmocore/src/timer.c:257 #5 0x00007ffff356255c in osmo_select_main (polling=0) at libosmocore/src/select.c:254 #6 0x00005555556f17cb in main (argc=3, argv=0x7fffffffe298) at osmo-sgsn/src/gprs/sgsn_main.c:531 Change-Id: I2120e53ade6cabad37f9bd99e6680a453411821b --- include/osmocom/sgsn/gprs_gmm.h | 2 ++ src/gprs/gprs_gmm.c | 10 ++++++++++ src/gprs/gprs_sgsn.c | 4 +--- 3 files changed, 13 insertions(+), 3 deletions(-) diff --git a/include/osmocom/sgsn/gprs_gmm.h b/include/osmocom/sgsn/gprs_gmm.h index 3c93efcb8..28c96ce67 100644 --- a/include/osmocom/sgsn/gprs_gmm.h +++ b/include/osmocom/sgsn/gprs_gmm.h @@ -43,4 +43,6 @@ int gsm48_tx_gmm_att_ack(struct sgsn_mm_ctx *mm); /* TODO: move extract_subscr_* when gsm48_gmm_authorize() got removed */ void extract_subscr_msisdn(struct sgsn_mm_ctx *ctx); void extract_subscr_hlr(struct sgsn_mm_ctx *ctx); + +void pdp_ctx_detach_mm_ctx(struct sgsn_pdp_ctx *pdp); #endif /* _GPRS_GMM_H */ diff --git a/src/gprs/gprs_gmm.c b/src/gprs/gprs_gmm.c index 6a5c5d9f3..9d8a8695a 100644 --- a/src/gprs/gprs_gmm.c +++ b/src/gprs/gprs_gmm.c @@ -2192,6 +2192,16 @@ static void pdpctx_timer_stop(struct sgsn_pdp_ctx *pdp, unsigned int T) osmo_timer_del(&pdp->timer); } +void pdp_ctx_detach_mm_ctx(struct sgsn_pdp_ctx *pdp) +{ + /* Detach from MM context */ + llist_del(&pdp->list); + pdp->mm = NULL; + + /* stop timer 3395 */ + pdpctx_timer_stop(pdp, 3395); +} + #if 0 static void msgb_put_pdp_addr_ipv4(struct msgb *msg, uint32_t ipaddr) { diff --git a/src/gprs/gprs_sgsn.c b/src/gprs/gprs_sgsn.c index 55ce09616..ab5e79ab6 100644 --- a/src/gprs/gprs_sgsn.c +++ b/src/gprs/gprs_sgsn.c @@ -443,9 +443,7 @@ void sgsn_pdp_ctx_terminate(struct sgsn_pdp_ctx *pdp) osmo_signal_dispatch(SS_SGSN, S_SGSN_PDP_TERMINATE, &sig_data); /* Detach from MM context */ - llist_del(&pdp->list); - pdp->mm = NULL; - + pdp_ctx_detach_mm_ctx(pdp); sgsn_delete_pdp_ctx(pdp); } -- cgit v1.2.3