SGSN: Avoid duplicate MM contexts in case MS and SGSN disagree on P-TMSI
diff --git a/openbsc/src/gprs/gprs_gmm.c b/openbsc/src/gprs/gprs_gmm.c
index ee6e366..4f1fe05 100644
--- a/openbsc/src/gprs/gprs_gmm.c
+++ b/openbsc/src/gprs/gprs_gmm.c
@@ -594,6 +594,19 @@
/* we already have a mm context with current TLLI, but no
* P-TMSI / IMSI yet. What we now need to do is to fill
* this initial context with data from the HLR */
+ if (strlen(ctx->imsi) == 0) {
+ /* Check if we already have a MM context for this IMSI */
+ struct sgsn_mm_ctx *ictx;
+ ictx = sgsn_mm_ctx_by_imsi(mi_string);
+ if (ictx) {
+ DEBUGP(DMM, "Deleting old MM Context for same IMSI ",
+ "p_tmsi_old=0x%08x, p_tmsi_new=0x%08x\n",
+ ictx->p_tmsi, ctx->p_tmsi);
+ gprs_llgmm_assign(ictx->llme, ictx->tlli,
+ 0xffffffff, GPRS_ALGO_GEA0, NULL);
+ sgsn_mm_ctx_free(ictx);
+ }
+ }
strncpy(ctx->imsi, mi_string, sizeof(ctx->imei));
break;
case GSM_MI_TYPE_IMEI:
@@ -704,6 +717,8 @@
if (!ctx)
ctx = sgsn_mm_ctx_by_ptmsi(tmsi);
if (!ctx) {
+ /* Allocate a context as most of our code expects one.
+ * Context will not have an IMSI ultil ID RESP is received */
ctx = sgsn_mm_ctx_alloc(msgb_tlli(msg), &ra_id);
ctx->p_tmsi = tmsi;
}