From 5ce54ba1e68ba2233f4d0cf94b12d6b4a3537399 Mon Sep 17 00:00:00 2001 From: Pau Espin Pedrol Date: Mon, 19 Oct 2020 16:38:25 +0200 Subject: 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 --- src/sgsn/gprs_sm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/src/sgsn/gprs_sm.c b/src/sgsn/gprs_sm.c index f8019ab6a..3bdad3bf6 100644 --- a/src/sgsn/gprs_sm.c +++ b/src/sgsn/gprs_sm.c @@ -639,7 +639,11 @@ static int gsm48_rx_gsm_deact_pdp_req(struct sgsn_mm_ctx *mm, struct msgb *msg) 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 ยง 9.5.9: Deactivate PDP Context Accept */ -- cgit v1.2.3