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authorPau Espin Pedrol <pespin@sysmocom.de>2018-07-09 20:44:17 +0200
committerPau Espin Pedrol <pespin@sysmocom.de>2018-07-13 11:51:52 +0200
commit8c7d2590611eba7a0c0a8e27cc9c4cbf1b5a6067 (patch)
tree74a119a443dc57bd81a0eb40c15c95512da2e4e5
parentfa1201004f85b6e44d746d6044d5a43d04634fa4 (diff)
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
-rw-r--r--include/osmocom/sgsn/gprs_gmm.h2
-rw-r--r--src/gprs/gprs_gmm.c10
-rw-r--r--src/gprs/gprs_sgsn.c4
3 files changed, 13 insertions, 3 deletions
diff --git a/include/osmocom/sgsn/gprs_gmm.h b/include/osmocom/sgsn/gprs_gmm.h
index 3c93efcb..28c96ce6 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 6a5c5d9f..9d8a8695 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 55ce0961..ab5e79ab 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);
}