Fix crash rx DeactPdpReq while waiting for DeactPdpAck after gtp side is freed
Scenario:
1- For an unknwon reason, sgsn sends DeletePdpCtxReq on GTP towards GGSN.
2- GGSN answers with Error Indication to that pdp ctx which calls
gtp_freepdp()
3- gtp_freepdp() calls libgtp callback cb_delete_context() before freeing the
pointer, in osmo-sgsn callback points to cb_delete_context(), which
removes pctx->ggsn and tries to drop the pdp on the NS side by sending a
DeactPdpReq.
4- While waiting for DeactPdpAck, the MS/PCU sends a DeactPdpReq, and
code was unconditionalyl trying to release the gtp side without checking
if it was alreay released, using pctx->ggsn==NULL and crashing.
This is basically the same logic already in place in regular path
gsm48_rx_gsm_deact_pdp_ack.
Related: OS#4817
Change-Id: I02587a3dc812823d893fc00b904142b75fd190b9
diff --git a/src/sgsn/gprs_sm.c b/src/sgsn/gprs_sm.c
index f8019ab..3bdad3b 100644
--- a/src/sgsn/gprs_sm.c
+++ b/src/sgsn/gprs_sm.c
@@ -639,7 +639,11 @@
return _gsm48_tx_gsm_deact_pdp_acc(mm, transaction_id);
}
- return sgsn_delete_pdp_ctx(pdp);
+ if (pdp->ggsn)
+ return sgsn_delete_pdp_ctx(pdp);
+ /* GTP side already detached, freeing */
+ sgsn_pdp_ctx_free(pdp);
+ return 0;
}
/* 3GPP TS 24.008 § 9.5.9: Deactivate PDP Context Accept */