althea-net / open5gs

Open5GS is a C-language Open Source implementation for 5G Core and EPC, i.e. the core network of LTE/NR network (Release-16)
https://open5gs.org
GNU Affero General Public License v3.0
1 stars 1 forks source link

[mme] store paging info during context release #86

Closed spencersevilla closed 9 months ago

spencersevilla commented 9 months ago

Somewhat convoluted bug with a simple fix. When MME receives a DownlinkDataNotification indicating an error and the UE is in state Connected, it (1) sends a UEContextRelease to teardown the existing S1AP sessions and then (2) sends a Paging message to the relevant enb to induce reconnection. We need to store Paging info in this function, before sending the ContextRelease, because otherwise we don't know the right bearer. If Paging info is not stored and the eNB never responds, we eventually get a crash emm-sm.c:140 because we cannot access the paging info.