Change in osmo-sgsn[master]: gtp: Fix crash using new libgtp cb_recovery API

[Pau Espin Pedrol]

Pau Espin Pedrol has uploaded this change for review. ( https://gerrit.osmocom.org/10025


Change subject: gtp: Fix crash using new libgtp cb_recovery API
......................................................................

gtp: Fix crash using new libgtp cb_recovery API

When PDP CTX CREATE ACK is received with an increased RestartCtr, cb_recovery
is called first, which will dettach ggsn from al pdp ctx (free the
pdp_t). But when giving control back from the ctrl, libgtp still uses
that freed ctx and sends it back to osmo-sgsn through cb_conf().

As specs state in any case that we need to handle the message containing
the increased RestartCtr as valid, we then need to avoid freeing the pdp
ctx and leave handling for later in cb_conf.

Change-Id: I0989c00e18ca95a099e1a312940eaac71957b444
---
M include/osmocom/sgsn/gprs_sgsn.h
M src/gprs/gprs_sgsn.c
M src/gprs/sgsn_libgtp.c
3 files changed, 13 insertions(+), 7 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-sgsn refs/changes/25/10025/1

diff --git a/include/osmocom/sgsn/gprs_sgsn.h b/include/osmocom/sgsn/gprs_sgsn.h
index 8eba2d4..6f16dc7 100644
--- a/include/osmocom/sgsn/gprs_sgsn.h
+++ b/include/osmocom/sgsn/gprs_sgsn.h
@@ -362,7 +362,7 @@
 struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_by_addr(struct in_addr *addr);
 struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_find_alloc(uint32_t id);
 void sgsn_ggsn_ctx_drop_pdp(struct sgsn_pdp_ctx *pctx);
-int sgsn_ggsn_ctx_drop_all_pdp(struct sgsn_ggsn_ctx *ggsn);
+int sgsn_ggsn_ctx_drop_all_pdp_except(struct sgsn_ggsn_ctx *ggsn, struct sgsn_pdp_ctx *except);
 void sgsn_ggsn_ctx_add_pdp(struct sgsn_ggsn_ctx *ggc, struct sgsn_pdp_ctx *pdp);
 void sgsn_ggsn_ctx_remove_pdp(struct sgsn_ggsn_ctx *ggc, struct sgsn_pdp_ctx *pdp);
 
diff --git a/src/gprs/gprs_sgsn.c b/src/gprs/gprs_sgsn.c
index e6d88e3..9046157 100644
--- a/src/gprs/gprs_sgsn.c
+++ b/src/gprs/gprs_sgsn.c
@@ -714,13 +714,17 @@
 }
 
 /* High-level function to be called in case a GGSN has disappeared or
- * otherwise lost state (recovery procedure) */
-int sgsn_ggsn_ctx_drop_all_pdp(struct sgsn_ggsn_ctx *ggsn)
+ * otherwise lost state (recovery procedure). It will detach all related pdp ctx
+ * from a ggsn and communicate deact to MS. Optionally (!NULL), one pdp ctx can
+ * be kept alive to allow handling later message which contained the Recovery IE. */
+int sgsn_ggsn_ctx_drop_all_pdp_except(struct sgsn_ggsn_ctx *ggsn, struct sgsn_pdp_ctx *except)
 {
 	int num = 0;
 
 	struct sgsn_pdp_ctx *pdp, *pdp2;
 	llist_for_each_entry_safe(pdp, pdp2, &ggsn->pdp_list, ggsn_list) {
+		if (pdp == except)
+			continue;
 		sgsn_ggsn_ctx_drop_pdp(pdp);
 		num++;
 	}
diff --git a/src/gprs/sgsn_libgtp.c b/src/gprs/sgsn_libgtp.c
index 2a9ba05..f042ddb 100644
--- a/src/gprs/sgsn_libgtp.c
+++ b/src/gprs/sgsn_libgtp.c
@@ -584,9 +584,10 @@
 }
 
 /* Any message received by GGSN contains a recovery IE */
-static int cb_recovery(struct sockaddr_in *peer, uint8_t recovery)
+static int cb_recovery(struct sockaddr_in *peer, struct pdp_t *pdp, uint8_t recovery)
 {
 	struct sgsn_ggsn_ctx *ggsn;
+	struct sgsn_pdp_ctx *pctx;
 
 	ggsn = sgsn_ggsn_ctx_by_addr(&peer->sin_addr);
 	if (!ggsn) {
@@ -599,11 +600,12 @@
 		ggsn->remote_restart_ctr = recovery;
 	} else if (ggsn->remote_restart_ctr != recovery) {
 		/* counter has changed (GGSN restart): release all PDP */
-		LOGP(DGPRS, LOGL_NOTICE, "GGSN recovery (%u->%u), "
+		LOGP(DGPRS, LOGL_NOTICE, "GGSN recovery (%u->%u) pdp=%p, "
 		     "releasing all PDP contexts\n",
-		     ggsn->remote_restart_ctr, recovery);
+		     ggsn->remote_restart_ctr, recovery, pdp);
 		ggsn->remote_restart_ctr = recovery;
-		sgsn_ggsn_ctx_drop_all_pdp(ggsn);
+		pctx = pdp->priv;
+		sgsn_ggsn_ctx_drop_all_pdp_except(ggsn, pctx);
 	}
 	return 0;
 }

-- 
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Gerrit-Project: osmo-sgsn
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I0989c00e18ca95a099e1a312940eaac71957b444
Gerrit-Change-Number: 10025
Gerrit-PatchSet: 1
Gerrit-Owner: Pau Espin Pedrol <pespin at sysmocom.de>
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